<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2022 Workiva-->
<!--r:4a28274b-9a25-4f4b-902b-d44ad9065c77,g:33409d08-1146-4085-81f8-8c047ab4661a-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://honestco.com/role/ConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit" xlink:type="simple" xlink:href="hnst-20211231.xsd#ConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit"/>
  <link:definitionLink xlink:role="http://honestco.com/role/ConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit" xlink:type="extended" id="i51cd60d6efa9450f871e32bbca97e656_ConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersEquityDeficit">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_a43ab72f-cda3-4e88-a205-be1f7b99178a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInTemporaryEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_a43ab72f-cda3-4e88-a205-be1f7b99178a" xlink:to="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_e8defcb8-6fb0-4481-88da-95bfa1659586" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_e8defcb8-6fb0-4481-88da-95bfa1659586" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_1e6e4f30-ce7b-4dcb-9eec-c5f55f926b13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_1e6e4f30-ce7b-4dcb-9eec-c5f55f926b13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_ef58c5f7-89dc-4c3d-a76c-c8f45895aeff" xlink:href="hnst-20211231.xsd#hnst_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_hnst_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues_ef58c5f7-89dc-4c3d-a76c-c8f45895aeff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_c4f274da-3599-43a2-aeef-718108ade1cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues_c4f274da-3599-43a2-aeef-718108ade1cb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_TemporaryEquityTemporaryEquityStockRepurchasedAndRetiredDuringPeriodShares_42a862ac-c15f-4da1-a99e-359c13fd10fb" xlink:href="hnst-20211231.xsd#hnst_TemporaryEquityTemporaryEquityStockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_hnst_TemporaryEquityTemporaryEquityStockRepurchasedAndRetiredDuringPeriodShares_42a862ac-c15f-4da1-a99e-359c13fd10fb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_TemporaryEquityStockRepurchasedAndRetiredDuringPeriodValue_b3c92539-5748-43ce-a9af-3251ea47b905" xlink:href="hnst-20211231.xsd#hnst_TemporaryEquityStockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_hnst_TemporaryEquityStockRepurchasedAndRetiredDuringPeriodValue_b3c92539-5748-43ce-a9af-3251ea47b905" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ReclassificationsOfTemporaryToPermanentEquityShares_8b4ec4cf-7d65-463e-a0fb-2cb89cb238e2" xlink:href="hnst-20211231.xsd#hnst_ReclassificationsOfTemporaryToPermanentEquityShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_hnst_ReclassificationsOfTemporaryToPermanentEquityShares_8b4ec4cf-7d65-463e-a0fb-2cb89cb238e2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationsOfTemporaryToPermanentEquity_00932940-71f2-4c9a-bec9-7834ec678331" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationsOfTemporaryToPermanentEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_c9e0516b-2dbc-4254-88d3-5b140d57436b" xlink:to="loc_us-gaap_ReclassificationsOfTemporaryToPermanentEquity_00932940-71f2-4c9a-bec9-7834ec678331" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_84318e8a-ebad-4541-afc7-acae3e2eaf08" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_23265d19-aa7c-47e0-9dc5-0f74857a3eda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_a43ab72f-cda3-4e88-a205-be1f7b99178a" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_fba7f51c-43b8-4322-a705-0e0c40a60eaa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_SharesOutstanding_fba7f51c-43b8-4322-a705-0e0c40a60eaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_88f9267a-f5e5-472d-9e09-8c7cdde3f13d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockholdersEquity_88f9267a-f5e5-472d-9e09-8c7cdde3f13d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_6211e089-fba2-4618-b684-bd59d7613c41" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_NetIncomeLoss_6211e089-fba2-4618-b684-bd59d7613c41" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_af829775-1904-41fb-8767-80db82920ae2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_af829775-1904-41fb-8767-80db82920ae2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_eafce043-4114-4153-a915-843c34553dc4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_eafce043-4114-4153-a915-843c34553dc4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_83e40960-e423-4d20-8b90-5b1d6004b719" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_83e40960-e423-4d20-8b90-5b1d6004b719" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_cfb32dbd-cedd-4a63-a38d-d616540023a9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_cfb32dbd-cedd-4a63-a38d-d616540023a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_3b2e62f4-1b95-4575-abc9-f1b462515cda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_3b2e62f4-1b95-4575-abc9-f1b462515cda" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_29dff6be-48a3-47dd-96c6-bd888f7ce170" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_DividendsCommonStockCash_29dff6be-48a3-47dd-96c6-bd888f7ce170" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_8db10bca-cc53-440d-bd43-3fbb8c76804a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_8db10bca-cc53-440d-bd43-3fbb8c76804a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_58fb468f-2cd3-43f3-805b-a26ee5abec73" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_58fb468f-2cd3-43f3-805b-a26ee5abec73" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_4422ba04-9b97-44cb-8273-42cc6a5a6fd7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_4422ba04-9b97-44cb-8273-42cc6a5a6fd7" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_b758b7a8-5626-4e32-b263-a1709b0d689e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_b758b7a8-5626-4e32-b263-a1709b0d689e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_e0c25cae-7577-4e63-8575-cfea8663b5ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_e0c25cae-7577-4e63-8575-cfea8663b5ef" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_85fe0546-3b1b-481e-8273-d4ecad9c5095" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_85fe0546-3b1b-481e-8273-d4ecad9c5095" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_ac1589ca-a50a-4171-a11d-bae2153d1bfc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_ac1589ca-a50a-4171-a11d-bae2153d1bfc" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_c6784640-9a47-4385-8b0f-fdcaaeddfaba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0e87f60a-cd5a-48d1-8863-839843b9cfcb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_c6784640-9a47-4385-8b0f-fdcaaeddfaba" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_3ac493b5-2e99-480c-9cba-1eb37e8bf297" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_48d943fa-0820-469e-b02e-7627a4dc8704" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdateExtensibleList_b621ba6f-9f9a-487e-b480-3ddd51d46a80" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdateExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_a43ab72f-cda3-4e88-a205-be1f7b99178a" xlink:to="loc_us-gaap_AccountingStandardsUpdateExtensibleList_b621ba6f-9f9a-487e-b480-3ddd51d46a80" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_dbce72ae-ea1a-4fe8-8e62-583b381795ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_a43ab72f-cda3-4e88-a205-be1f7b99178a" xlink:to="loc_us-gaap_StatementTable_dbce72ae-ea1a-4fe8-8e62-583b381795ca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_1cfefa4e-6d84-4cc6-8612-8c3cfd6e9a44" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_dbce72ae-ea1a-4fe8-8e62-583b381795ca" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_1cfefa4e-6d84-4cc6-8612-8c3cfd6e9a44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_1cfefa4e-6d84-4cc6-8612-8c3cfd6e9a44_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1cfefa4e-6d84-4cc6-8612-8c3cfd6e9a44" xlink:to="loc_us-gaap_EquityComponentDomain_1cfefa4e-6d84-4cc6-8612-8c3cfd6e9a44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2bf78760-ae1f-4317-a5cd-78a256a21b90" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1cfefa4e-6d84-4cc6-8612-8c3cfd6e9a44" xlink:to="loc_us-gaap_EquityComponentDomain_2bf78760-ae1f-4317-a5cd-78a256a21b90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_a35e97b5-bc7e-4c6b-ba80-2b9a024bab20" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2bf78760-ae1f-4317-a5cd-78a256a21b90" xlink:to="loc_us-gaap_CommonStockMember_a35e97b5-bc7e-4c6b-ba80-2b9a024bab20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_542f58e0-6ebe-4be1-92dd-ab2b0e8d7998" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2bf78760-ae1f-4317-a5cd-78a256a21b90" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_542f58e0-6ebe-4be1-92dd-ab2b0e8d7998" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_12d21b9a-85db-4250-baa7-bc46cc917e1d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2bf78760-ae1f-4317-a5cd-78a256a21b90" xlink:to="loc_us-gaap_RetainedEarningsMember_12d21b9a-85db-4250-baa7-bc46cc917e1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_265d9af2-8c47-431c-b6c9-02f506cc4ef9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2bf78760-ae1f-4317-a5cd-78a256a21b90" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_265d9af2-8c47-431c-b6c9-02f506cc4ef9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8c256915-7a3f-42c4-a4aa-f89c142bb2ef" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_dbce72ae-ea1a-4fe8-8e62-583b381795ca" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8c256915-7a3f-42c4-a4aa-f89c142bb2ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8c256915-7a3f-42c4-a4aa-f89c142bb2ef_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8c256915-7a3f-42c4-a4aa-f89c142bb2ef" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8c256915-7a3f-42c4-a4aa-f89c142bb2ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_d297feba-f07c-4ef5-aad4-fccd1e576db0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8c256915-7a3f-42c4-a4aa-f89c142bb2ef" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_d297feba-f07c-4ef5-aad4-fccd1e576db0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_0881d200-c9e3-483e-b141-4ddc72d60475" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_d297feba-f07c-4ef5-aad4-fccd1e576db0" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_0881d200-c9e3-483e-b141-4ddc72d60475" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/NatureofBusinessDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#NatureofBusinessDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/NatureofBusinessDetails" xlink:type="extended" id="i913445bf001f4e56b16e4dbe84b8e248_NatureofBusinessDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsidiarySaleOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_5a1e323f-b0c9-4f1b-a71d-bdfce684168c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_5a1e323f-b0c9-4f1b-a71d-bdfce684168c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_a0c00803-66d2-4867-bb6b-8167c982f904" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_a0c00803-66d2-4867-bb6b-8167c982f904" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_471334b0-a640-401b-b3b4-b624b8955b2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_471334b0-a640-401b-b3b4-b624b8955b2e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_90409e6d-83e5-4796-b5fb-a32f16202ac3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_90409e6d-83e5-4796-b5fb-a32f16202ac3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_22e2f936-e2a0-4fa1-b0fc-1750b77ec06c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_22e2f936-e2a0-4fa1-b0fc-1750b77ec06c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SaleOfStockOptionToPurchaseAdditionalSharesPeriod_3d910afc-7af7-4875-bc28-cd47a3e4c40b" xlink:href="hnst-20211231.xsd#hnst_SaleOfStockOptionToPurchaseAdditionalSharesPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_hnst_SaleOfStockOptionToPurchaseAdditionalSharesPeriod_3d910afc-7af7-4875-bc28-cd47a3e4c40b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToEmployees_95479e96-b0c6-494b-a17e-5acb5c592f18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToEmployees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_PaymentsToEmployees_95479e96-b0c6-494b-a17e-5acb5c592f18" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_5c709e6d-4535-4162-8830-df1633525b07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrentAndNoncurrent_5c709e6d-4535-4162-8830-df1633525b07" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_f09628f4-2b73-41cf-abd9-437a294999ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_f09628f4-2b73-41cf-abd9-437a294999ab" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_69905271-bc75-4bd9-bf3d-00df9bdb4243" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_69905271-bc75-4bd9-bf3d-00df9bdb4243" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_1b112e3c-1335-429f-999f-813b80537883" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_1b112e3c-1335-429f-999f-813b80537883" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_93c86367-73d0-44b5-a0a9-cbebd752d5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_93c86367-73d0-44b5-a0a9-cbebd752d5a3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_430e14ec-9767-4470-87b1-078e040ca12e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_430e14ec-9767-4470-87b1-078e040ca12e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_c6206c09-d258-412e-b9af-e11decc48b53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_c6206c09-d258-412e-b9af-e11decc48b53" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_f40ae309-05b3-40fa-bd42-c97341d56f66" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_f40ae309-05b3-40fa-bd42-c97341d56f66" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_9c2f9c9d-d91a-4cb1-88c5-c5c47047a699" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_887ca140-de25-45cc-9692-a9d3054e802d" xlink:to="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_9c2f9c9d-d91a-4cb1-88c5-c5c47047a699" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_7c852348-8ffd-41ee-b710-0a08d3d0a2a2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_9c2f9c9d-d91a-4cb1-88c5-c5c47047a699" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_7c852348-8ffd-41ee-b710-0a08d3d0a2a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7c852348-8ffd-41ee-b710-0a08d3d0a2a2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_7c852348-8ffd-41ee-b710-0a08d3d0a2a2" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7c852348-8ffd-41ee-b710-0a08d3d0a2a2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_08826280-acf4-44c0-86d5-70ce79b83a8d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_7c852348-8ffd-41ee-b710-0a08d3d0a2a2" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_08826280-acf4-44c0-86d5-70ce79b83a8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_02d0406f-d05d-4d9e-b1d4-8a3b25ae9e45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IPOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_08826280-acf4-44c0-86d5-70ce79b83a8d" xlink:to="loc_us-gaap_IPOMember_02d0406f-d05d-4d9e-b1d4-8a3b25ae9e45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_IPOSoldByCompanyMember_e56f17fe-2855-48de-99fa-1397a6cf0baa" xlink:href="hnst-20211231.xsd#hnst_IPOSoldByCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IPOMember_02d0406f-d05d-4d9e-b1d4-8a3b25ae9e45" xlink:to="loc_hnst_IPOSoldByCompanyMember_e56f17fe-2855-48de-99fa-1397a6cf0baa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_IPOSoldByExistingShareholdersMember_a309cd91-36bb-47f0-80ee-23cece66c453" xlink:href="hnst-20211231.xsd#hnst_IPOSoldByExistingShareholdersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IPOMember_02d0406f-d05d-4d9e-b1d4-8a3b25ae9e45" xlink:to="loc_hnst_IPOSoldByExistingShareholdersMember_a309cd91-36bb-47f0-80ee-23cece66c453" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_IPOOtherOfferingExpenseMember_1cca7491-f351-4196-96f2-02a890a18a76" xlink:href="hnst-20211231.xsd#hnst_IPOOtherOfferingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IPOMember_02d0406f-d05d-4d9e-b1d4-8a3b25ae9e45" xlink:to="loc_hnst_IPOOtherOfferingExpenseMember_1cca7491-f351-4196-96f2-02a890a18a76" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OverAllotmentOptionMember_e057ebe7-8934-4a23-9c28-6ef020e80845" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OverAllotmentOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_08826280-acf4-44c0-86d5-70ce79b83a8d" xlink:to="loc_us-gaap_OverAllotmentOptionMember_e057ebe7-8934-4a23-9c28-6ef020e80845" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_88c2eee2-a436-4e65-b7e3-cd0a68f6af2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_9c2f9c9d-d91a-4cb1-88c5-c5c47047a699" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_88c2eee2-a436-4e65-b7e3-cd0a68f6af2e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_88c2eee2-a436-4e65-b7e3-cd0a68f6af2e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_88c2eee2-a436-4e65-b7e3-cd0a68f6af2e" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_88c2eee2-a436-4e65-b7e3-cd0a68f6af2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_40e9cdcb-e989-4f66-9d5c-677a3876d719" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_88c2eee2-a436-4e65-b7e3-cd0a68f6af2e" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_40e9cdcb-e989-4f66-9d5c-677a3876d719" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_80a01200-f453-4ba3-87f5-1c7bdd080c1f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_40e9cdcb-e989-4f66-9d5c-677a3876d719" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_80a01200-f453-4ba3-87f5-1c7bdd080c1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_d8fcf62c-c65b-47fa-a7f8-e956eb3de9c4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_40e9cdcb-e989-4f66-9d5c-677a3876d719" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_d8fcf62c-c65b-47fa-a7f8-e956eb3de9c4" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/SummaryofSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#SummaryofSignificantAccountingPoliciesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/SummaryofSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="extended" id="i71dfe15bf906476ca9f7e304a6a9347c_SummaryofSignificantAccountingPoliciesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_0a0d9427-8749-4107-87fd-3e7b6df83626" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_0a0d9427-8749-4107-87fd-3e7b6df83626" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_e948cee2-ae8e-4056-bdd5-d7813b41f8db" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_NumberOfOperatingSegments_e948cee2-ae8e-4056-bdd5-d7813b41f8db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown_e6f366f1-8d8d-46e5-9d9f-a8f0d073c38a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InventoryWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_InventoryWriteDown_e6f366f1-8d8d-46e5-9d9f-a8f0d073c38a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_InventoryAdjustmentsDonation_79a2b951-4dcd-4320-bdff-b2a922d21fba" xlink:href="hnst-20211231.xsd#hnst_InventoryAdjustmentsDonation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_hnst_InventoryAdjustmentsDonation_79a2b951-4dcd-4320-bdff-b2a922d21fba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_28c11908-0c9b-43f9-b3b4-aa75ee502efc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_28c11908-0c9b-43f9-b3b4-aa75ee502efc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOfferingCosts_b8aa98d9-9ca3-4667-91f8-d6428d2e01f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredOfferingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_DeferredOfferingCosts_b8aa98d9-9ca3-4667-91f8-d6428d2e01f4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredRentCreditCurrent_e22045e1-e044-4c5f-8476-4f6604108f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredRentCreditCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_DeferredRentCreditCurrent_e22045e1-e044-4c5f-8476-4f6604108f9a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredRentCreditNoncurrent_9f2c9251-7998-4c47-973e-59c72ca29138" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredRentCreditNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_DeferredRentCreditNoncurrent_9f2c9251-7998-4c47-973e-59c72ca29138" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HostingArrangementServiceContractImplementationCostCapitalizedAfterAccumulatedAmortization_32489ec9-b1b0-423f-a3e5-34ba89632454" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HostingArrangementServiceContractImplementationCostCapitalizedAfterAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_HostingArrangementServiceContractImplementationCostCapitalizedAfterAccumulatedAmortization_32489ec9-b1b0-423f-a3e5-34ba89632454" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HostingArrangementServiceContractImplementationCostCapitalizedAccumulatedAmortization_78dfc099-d610-4c6f-b1d3-653343390a77" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HostingArrangementServiceContractImplementationCostCapitalizedAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_HostingArrangementServiceContractImplementationCostCapitalizedAccumulatedAmortization_78dfc099-d610-4c6f-b1d3-653343390a77" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_85250971-c7ff-42e2-8b8b-4cc3ef3b6c4a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_85250971-c7ff-42e2-8b8b-4cc3ef3b6c4a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_fb311605-ac91-44ef-a144-933a6b97a3c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_fb311605-ac91-44ef-a144-933a6b97a3c8" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_17f80df2-7aae-4438-bc3b-fbc8ad3c6c75" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_17f80df2-7aae-4438-bc3b-fbc8ad3c6c75" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_8ac6ae10-3e67-4dba-aced-c277dc79aa58" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_8ac6ae10-3e67-4dba-aced-c277dc79aa58" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_4e4920d2-9722-46fe-a342-263d74136b99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_4e4920d2-9722-46fe-a342-263d74136b99" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_766ae1b5-51c0-4bfd-adba-59ed35ab403c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_766ae1b5-51c0-4bfd-adba-59ed35ab403c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DeferredAdvertisingCostAmortizationPeriod_b12e869d-98c2-4191-b7d5-020bebd1f73a" xlink:href="hnst-20211231.xsd#hnst_DeferredAdvertisingCostAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_hnst_DeferredAdvertisingCostAmortizationPeriod_b12e869d-98c2-4191-b7d5-020bebd1f73a" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCurrent_8f6c4622-d51e-40e5-8adb-fd069975c476" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCostsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_DeferredCostsCurrent_8f6c4622-d51e-40e5-8adb-fd069975c476" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCosts_660cf20e-da16-4b0b-8842-593e5181f1f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_DeferredCosts_660cf20e-da16-4b0b-8842-593e5181f1f2" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_a259d3e3-fa17-4d56-a169-d9dc4781ab5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_AdvertisingExpense_a259d3e3-fa17-4d56-a169-d9dc4781ab5a" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_9d321bf9-f5e9-4172-8308-ecb3e9821774" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_9d321bf9-f5e9-4172-8308-ecb3e9821774" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_6ba5fa07-4bee-474f-81e2-97ad7e6997c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_OperatingLeaseLiability_6ba5fa07-4bee-474f-81e2-97ad7e6997c0" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_00b8f438-9b4a-4d3a-890e-1797f58cbe3e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_Assets_00b8f438-9b4a-4d3a-890e-1797f58cbe3e" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_d8ca25f0-7248-4d2f-aacc-c118bcd3126a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_Liabilities_d8ca25f0-7248-4d2f-aacc-c118bcd3126a" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_599590c0-9aa4-430f-8dc8-9f8d9b248c29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_StockholdersEquity_599590c0-9aa4-430f-8dc8-9f8d9b248c29" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_0298f23f-9167-4592-bebf-8170843ecb98" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_5f025268-2d80-4cc3-b0fc-c8681faa3559" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_StatementClassOfStockAxis_5f025268-2d80-4cc3-b0fc-c8681faa3559" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5f025268-2d80-4cc3-b0fc-c8681faa3559_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5f025268-2d80-4cc3-b0fc-c8681faa3559" xlink:to="loc_us-gaap_ClassOfStockDomain_5f025268-2d80-4cc3-b0fc-c8681faa3559_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7ff811c0-86e8-492c-94bd-c93d994985ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5f025268-2d80-4cc3-b0fc-c8681faa3559" xlink:to="loc_us-gaap_ClassOfStockDomain_7ff811c0-86e8-492c-94bd-c93d994985ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_164827ab-f2e0-4177-b3c0-adf51d171c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7ff811c0-86e8-492c-94bd-c93d994985ad" xlink:to="loc_us-gaap_CommonStockMember_164827ab-f2e0-4177-b3c0-adf51d171c5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_3fd5fe25-e278-4e59-b201-47051a021561" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7ff811c0-86e8-492c-94bd-c93d994985ad" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_3fd5fe25-e278-4e59-b201-47051a021561" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_58ef7cc3-b14d-47a5-b18c-3abaf5288f68" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PublicUtilitiesInventoryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_58ef7cc3-b14d-47a5-b18c-3abaf5288f68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_58ef7cc3-b14d-47a5-b18c-3abaf5288f68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_58ef7cc3-b14d-47a5-b18c-3abaf5288f68" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_58ef7cc3-b14d-47a5-b18c-3abaf5288f68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_5b5f99bd-64e8-4899-9672-f03a6798d5bb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_58ef7cc3-b14d-47a5-b18c-3abaf5288f68" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_5b5f99bd-64e8-4899-9672-f03a6798d5bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SanitizationAndDisinfectingProductsMember_2b9fe1b7-b6eb-4022-b392-c391e4e0dea8" xlink:href="hnst-20211231.xsd#hnst_SanitizationAndDisinfectingProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_5b5f99bd-64e8-4899-9672-f03a6798d5bb" xlink:to="loc_hnst_SanitizationAndDisinfectingProductsMember_2b9fe1b7-b6eb-4022-b392-c391e4e0dea8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_FaceMasksMember_e14ef167-311e-47cf-a9ac-386248803657" xlink:href="hnst-20211231.xsd#hnst_FaceMasksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_5b5f99bd-64e8-4899-9672-f03a6798d5bb" xlink:to="loc_hnst_FaceMasksMember_e14ef167-311e-47cf-a9ac-386248803657" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_241111ea-5213-456e-be2c-88c54fe68358" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_srt_ProductOrServiceAxis_241111ea-5213-456e-be2c-88c54fe68358" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_241111ea-5213-456e-be2c-88c54fe68358_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_241111ea-5213-456e-be2c-88c54fe68358" xlink:to="loc_srt_ProductsAndServicesDomain_241111ea-5213-456e-be2c-88c54fe68358_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_356ab318-59c7-4592-814c-23acfe14e9c0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_241111ea-5213-456e-be2c-88c54fe68358" xlink:to="loc_srt_ProductsAndServicesDomain_356ab318-59c7-4592-814c-23acfe14e9c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_HouseholdAndWellnessMember_d6765fcc-e9fb-4dab-aae9-0e6337eb1515" xlink:href="hnst-20211231.xsd#hnst_HouseholdAndWellnessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_356ab318-59c7-4592-814c-23acfe14e9c0" xlink:to="loc_hnst_HouseholdAndWellnessMember_d6765fcc-e9fb-4dab-aae9-0e6337eb1515" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_GiftCardMember_e0a17e62-8ee8-4359-bde4-284464394c40" xlink:href="hnst-20211231.xsd#hnst_GiftCardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_356ab318-59c7-4592-814c-23acfe14e9c0" xlink:to="loc_hnst_GiftCardMember_e0a17e62-8ee8-4359-bde4-284464394c40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_63ed8818-cafd-41fd-a066-6cf7bcfbb903" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_63ed8818-cafd-41fd-a066-6cf7bcfbb903" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_63ed8818-cafd-41fd-a066-6cf7bcfbb903_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_63ed8818-cafd-41fd-a066-6cf7bcfbb903" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_63ed8818-cafd-41fd-a066-6cf7bcfbb903_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_b084bee9-6246-4ce6-9f5e-b1422be0ff61" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_63ed8818-cafd-41fd-a066-6cf7bcfbb903" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_b084bee9-6246-4ce6-9f5e-b1422be0ff61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_a323fb6a-93e1-4f84-be4f-14c27a2ec15d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_b084bee9-6246-4ce6-9f5e-b1422be0ff61" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_a323fb6a-93e1-4f84-be4f-14c27a2ec15d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_1da7d74e-fbd3-41c5-ae3e-3b038b343431" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_srt_StatementScenarioAxis_1da7d74e-fbd3-41c5-ae3e-3b038b343431" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_1da7d74e-fbd3-41c5-ae3e-3b038b343431_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_1da7d74e-fbd3-41c5-ae3e-3b038b343431" xlink:to="loc_srt_ScenarioUnspecifiedDomain_1da7d74e-fbd3-41c5-ae3e-3b038b343431_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_4fc8c09e-4226-40d8-8eeb-b13cba79894a" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_1da7d74e-fbd3-41c5-ae3e-3b038b343431" xlink:to="loc_srt_ScenarioUnspecifiedDomain_4fc8c09e-4226-40d8-8eeb-b13cba79894a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_0e7aab24-6602-429d-96b9-8bf9ff6afdd2" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_4fc8c09e-4226-40d8-8eeb-b13cba79894a" xlink:to="loc_srt_ScenarioForecastMember_0e7aab24-6602-429d-96b9-8bf9ff6afdd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1defe497-5d74-4227-a87b-49fcc36fad24" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1defe497-5d74-4227-a87b-49fcc36fad24" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_1defe497-5d74-4227-a87b-49fcc36fad24_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1defe497-5d74-4227-a87b-49fcc36fad24" xlink:to="loc_us-gaap_TypeOfAdoptionMember_1defe497-5d74-4227-a87b-49fcc36fad24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_58749869-9efc-47ad-bd2f-aed76e3af48a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_1defe497-5d74-4227-a87b-49fcc36fad24" xlink:to="loc_us-gaap_TypeOfAdoptionMember_58749869-9efc-47ad-bd2f-aed76e3af48a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_5081a812-2598-4da7-b0f6-29b2aa91de92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_58749869-9efc-47ad-bd2f-aed76e3af48a" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_5081a812-2598-4da7-b0f6-29b2aa91de92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_f009a2fa-57b6-45ad-9348-dc4edbb27357" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_srt_RangeAxis_f009a2fa-57b6-45ad-9348-dc4edbb27357" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f009a2fa-57b6-45ad-9348-dc4edbb27357_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_f009a2fa-57b6-45ad-9348-dc4edbb27357" xlink:to="loc_srt_RangeMember_f009a2fa-57b6-45ad-9348-dc4edbb27357_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_63361eff-9453-460a-b255-590dda45b29c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_f009a2fa-57b6-45ad-9348-dc4edbb27357" xlink:to="loc_srt_RangeMember_63361eff-9453-460a-b255-590dda45b29c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_e95951f2-5f1e-4fa2-964e-bcff36eb8725" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_63361eff-9453-460a-b255-590dda45b29c" xlink:to="loc_srt_MinimumMember_e95951f2-5f1e-4fa2-964e-bcff36eb8725" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_7e1ec864-d546-414b-8928-0eb46500d586" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_63361eff-9453-460a-b255-590dda45b29c" xlink:to="loc_srt_MaximumMember_7e1ec864-d546-414b-8928-0eb46500d586" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_fab942a0-9f4c-46c9-a4d1-ace1837579ba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_fab942a0-9f4c-46c9-a4d1-ace1837579ba" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_fab942a0-9f4c-46c9-a4d1-ace1837579ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_fab942a0-9f4c-46c9-a4d1-ace1837579ba" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_fab942a0-9f4c-46c9-a4d1-ace1837579ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_9e7e487e-f7bc-40b4-bf75-e2abb704d377" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_fab942a0-9f4c-46c9-a4d1-ace1837579ba" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_9e7e487e-f7bc-40b4-bf75-e2abb704d377" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_8bc2a78f-293c-4281-8fe3-e5ce6327c82f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_9e7e487e-f7bc-40b4-bf75-e2abb704d377" xlink:to="loc_us-gaap_AccountsReceivableMember_8bc2a78f-293c-4281-8fe3-e5ce6327c82f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_c0898ae2-3b10-4645-b5e4-f786fd78f7fb" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_c0898ae2-3b10-4645-b5e4-f786fd78f7fb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_c0898ae2-3b10-4645-b5e4-f786fd78f7fb_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_c0898ae2-3b10-4645-b5e4-f786fd78f7fb" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_c0898ae2-3b10-4645-b5e4-f786fd78f7fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_7dac9cd7-bd8b-4629-9688-0e18b90e5bdc" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_c0898ae2-3b10-4645-b5e4-f786fd78f7fb" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_7dac9cd7-bd8b-4629-9688-0e18b90e5bdc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_1d4faeb5-f161-47b5-850e-d535558d01ab" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_7dac9cd7-bd8b-4629-9688-0e18b90e5bdc" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_1d4faeb5-f161-47b5-850e-d535558d01ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_95fd6d0d-59a0-4acf-a25d-8d40e062f8f5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_95fd6d0d-59a0-4acf-a25d-8d40e062f8f5" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_95fd6d0d-59a0-4acf-a25d-8d40e062f8f5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_95fd6d0d-59a0-4acf-a25d-8d40e062f8f5" xlink:to="loc_us-gaap_EquityComponentDomain_95fd6d0d-59a0-4acf-a25d-8d40e062f8f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_abb76cc1-1c0b-4857-b6bc-2f4209504fe2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_95fd6d0d-59a0-4acf-a25d-8d40e062f8f5" xlink:to="loc_us-gaap_EquityComponentDomain_abb76cc1-1c0b-4857-b6bc-2f4209504fe2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_e569bb81-ff33-4b97-ba30-e3f96b41b2b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_abb76cc1-1c0b-4857-b6bc-2f4209504fe2" xlink:to="loc_us-gaap_RetainedEarningsMember_e569bb81-ff33-4b97-ba30-e3f96b41b2b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_44852274-0816-4c12-9d31-4fdab9c46285" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_f70dfc03-2c04-4769-8551-0755cf932f9a" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_44852274-0816-4c12-9d31-4fdab9c46285" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_44852274-0816-4c12-9d31-4fdab9c46285_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_44852274-0816-4c12-9d31-4fdab9c46285" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_44852274-0816-4c12-9d31-4fdab9c46285_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_9fba7975-324f-411f-a97c-5883843f44e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_44852274-0816-4c12-9d31-4fdab9c46285" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_9fba7975-324f-411f-a97c-5883843f44e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_AllowanceSalesIncentiveMember_99376103-7e13-41b7-b20e-4a0e45c6a753" xlink:href="hnst-20211231.xsd#hnst_AllowanceSalesIncentiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_9fba7975-324f-411f-a97c-5883843f44e6" xlink:to="loc_hnst_AllowanceSalesIncentiveMember_99376103-7e13-41b7-b20e-4a0e45c6a753" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails" xlink:type="extended" id="i1f01a627b5174490a94f3fa1da346265_SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_7e85290e-12f9-456c-b5a6-af88872b3259" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_7d915f98-db80-4d40-9126-3c064ba04768" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_7e85290e-12f9-456c-b5a6-af88872b3259" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_7d915f98-db80-4d40-9126-3c064ba04768" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_f20b2985-9ce4-4a66-b37e-1730991deabf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_7e85290e-12f9-456c-b5a6-af88872b3259" xlink:to="loc_us-gaap_ConcentrationRiskTable_f20b2985-9ce4-4a66-b37e-1730991deabf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_bbc68287-0ba9-47d1-81c3-1d43d2577090" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f20b2985-9ce4-4a66-b37e-1730991deabf" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_bbc68287-0ba9-47d1-81c3-1d43d2577090" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_bbc68287-0ba9-47d1-81c3-1d43d2577090_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_bbc68287-0ba9-47d1-81c3-1d43d2577090" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_bbc68287-0ba9-47d1-81c3-1d43d2577090_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_d1e19dd7-c6b2-4335-bc64-85bf201bcde1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_bbc68287-0ba9-47d1-81c3-1d43d2577090" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_d1e19dd7-c6b2-4335-bc64-85bf201bcde1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_0389b45d-d230-45b1-8226-6c9bd7f4466d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_d1e19dd7-c6b2-4335-bc64-85bf201bcde1" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_0389b45d-d230-45b1-8226-6c9bd7f4466d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_881f3386-7ae9-420f-a5ea-d5daee5d71aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f20b2985-9ce4-4a66-b37e-1730991deabf" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_881f3386-7ae9-420f-a5ea-d5daee5d71aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_881f3386-7ae9-420f-a5ea-d5daee5d71aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_881f3386-7ae9-420f-a5ea-d5daee5d71aa" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_881f3386-7ae9-420f-a5ea-d5daee5d71aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_8556c58c-68df-4821-b918-3f10df2ca16c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_881f3386-7ae9-420f-a5ea-d5daee5d71aa" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_8556c58c-68df-4821-b918-3f10df2ca16c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_0f09b532-1ed3-4240-a496-9a2e4b556051" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_8556c58c-68df-4821-b918-3f10df2ca16c" xlink:to="loc_us-gaap_AccountsReceivableMember_0f09b532-1ed3-4240-a496-9a2e4b556051" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_cf25bc22-27ed-4cdf-8feb-ff72d37185b1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_8556c58c-68df-4821-b918-3f10df2ca16c" xlink:to="loc_us-gaap_SalesRevenueNetMember_cf25bc22-27ed-4cdf-8feb-ff72d37185b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_fa70e358-7091-4570-b796-6f36a561e7c3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f20b2985-9ce4-4a66-b37e-1730991deabf" xlink:to="loc_srt_MajorCustomersAxis_fa70e358-7091-4570-b796-6f36a561e7c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_fa70e358-7091-4570-b796-6f36a561e7c3_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_fa70e358-7091-4570-b796-6f36a561e7c3" xlink:to="loc_srt_NameOfMajorCustomerDomain_fa70e358-7091-4570-b796-6f36a561e7c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_953b2108-14a7-4209-9486-c429ebb73fde" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_fa70e358-7091-4570-b796-6f36a561e7c3" xlink:to="loc_srt_NameOfMajorCustomerDomain_953b2108-14a7-4209-9486-c429ebb73fde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_CustomerAMember_307f3480-f5f7-4056-b887-20f4613d5087" xlink:href="hnst-20211231.xsd#hnst_CustomerAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_953b2108-14a7-4209-9486-c429ebb73fde" xlink:to="loc_hnst_CustomerAMember_307f3480-f5f7-4056-b887-20f4613d5087" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_CustomerBMember_cbde3bfe-03d6-40fb-95c2-4af6a3fa5776" xlink:href="hnst-20211231.xsd#hnst_CustomerBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_953b2108-14a7-4209-9486-c429ebb73fde" xlink:to="loc_hnst_CustomerBMember_cbde3bfe-03d6-40fb-95c2-4af6a3fa5776" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/SummaryofSignificantAccountingPoliciesUsefulLifeofAssetsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#SummaryofSignificantAccountingPoliciesUsefulLifeofAssetsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/SummaryofSignificantAccountingPoliciesUsefulLifeofAssetsDetails" xlink:type="extended" id="i374bbd153d034412a331feb57a00aeb8_SummaryofSignificantAccountingPoliciesUsefulLifeofAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_005c9286-d83d-4600-bd69-25d008085d22" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_142294b6-fa17-40b6-a642-050d56dbd0ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_005c9286-d83d-4600-bd69-25d008085d22" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_142294b6-fa17-40b6-a642-050d56dbd0ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_74f77490-910a-43f2-8ab5-5386bd02bcee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_005c9286-d83d-4600-bd69-25d008085d22" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_74f77490-910a-43f2-8ab5-5386bd02bcee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bf38b97e-591f-4bae-8bbd-b7f3198a59b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_74f77490-910a-43f2-8ab5-5386bd02bcee" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bf38b97e-591f-4bae-8bbd-b7f3198a59b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_bf38b97e-591f-4bae-8bbd-b7f3198a59b0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bf38b97e-591f-4bae-8bbd-b7f3198a59b0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_bf38b97e-591f-4bae-8bbd-b7f3198a59b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bf38b97e-591f-4bae-8bbd-b7f3198a59b0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_48f9138c-7423-44d1-8bde-ceb835b56a5c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_48f9138c-7423-44d1-8bde-ceb835b56a5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ComputerAndOfficeEquipmentMember_865c6a18-8dff-4b0f-8632-37cc1ee0ed0a" xlink:href="hnst-20211231.xsd#hnst_ComputerAndOfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:to="loc_hnst_ComputerAndOfficeEquipmentMember_865c6a18-8dff-4b0f-8632-37cc1ee0ed0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_b58beae9-461d-4a04-9f7a-23e892c4a5cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_b58beae9-461d-4a04-9f7a-23e892c4a5cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_ab2c9240-b7a1-4b82-90ad-347553b6b374" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_ab2c9240-b7a1-4b82-90ad-347553b6b374" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_80c24bab-a956-4265-8e32-b009b280c25d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_75cb35ba-9357-4eb6-b502-9472a0ead23e" xlink:to="loc_us-gaap_BuildingMember_80c24bab-a956-4265-8e32-b009b280c25d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_1dc733f9-fd0a-4e57-ab7b-0d621dd60c73" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_74f77490-910a-43f2-8ab5-5386bd02bcee" xlink:to="loc_srt_RangeAxis_1dc733f9-fd0a-4e57-ab7b-0d621dd60c73" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1dc733f9-fd0a-4e57-ab7b-0d621dd60c73_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_1dc733f9-fd0a-4e57-ab7b-0d621dd60c73" xlink:to="loc_srt_RangeMember_1dc733f9-fd0a-4e57-ab7b-0d621dd60c73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4e073e8d-135c-4933-bb76-70a9c602bd97" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_1dc733f9-fd0a-4e57-ab7b-0d621dd60c73" xlink:to="loc_srt_RangeMember_4e073e8d-135c-4933-bb76-70a9c602bd97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_bceb5308-b40d-4a6f-8c0d-5df983f46138" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4e073e8d-135c-4933-bb76-70a9c602bd97" xlink:to="loc_srt_MinimumMember_bceb5308-b40d-4a6f-8c0d-5df983f46138" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_6ce19964-b1ff-4112-a55f-d2099b0d91c3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4e073e8d-135c-4933-bb76-70a9c602bd97" xlink:to="loc_srt_MaximumMember_6ce19964-b1ff-4112-a55f-d2099b0d91c3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/SummaryofSignificantAccountingPoliciesSummaryofSalesIncentiveProgramActivityDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#SummaryofSignificantAccountingPoliciesSummaryofSalesIncentiveProgramActivityDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/SummaryofSignificantAccountingPoliciesSummaryofSalesIncentiveProgramActivityDetails" xlink:type="extended" id="id4ae4ff31b704aa7bc48f62701dbdcd2_SummaryofSignificantAccountingPoliciesSummaryofSalesIncentiveProgramActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_a4dc0edc-ebee-4aa3-b408-66bcede557b8" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_0b80dc26-14c8-4a49-b9c9-d85dbfa8b560" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_a4dc0edc-ebee-4aa3-b408-66bcede557b8" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_0b80dc26-14c8-4a49-b9c9-d85dbfa8b560" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_f7579ee1-bc2f-4404-ad80-cb17e74d85f7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_0b80dc26-14c8-4a49-b9c9-d85dbfa8b560" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_f7579ee1-bc2f-4404-ad80-cb17e74d85f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts_dfa20c89-5a6f-459b-b948-7a807694f690" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_0b80dc26-14c8-4a49-b9c9-d85dbfa8b560" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts_dfa20c89-5a6f-459b-b948-7a807694f690" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_a3087c14-4c2a-4f82-a612-b310a9159863" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_0b80dc26-14c8-4a49-b9c9-d85dbfa8b560" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_a3087c14-4c2a-4f82-a612-b310a9159863" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_8cb3e0bc-15ba-4fe1-bed9-59e412ee9723" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_0b80dc26-14c8-4a49-b9c9-d85dbfa8b560" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_8cb3e0bc-15ba-4fe1-bed9-59e412ee9723" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_82ca2cc0-0aed-4a8e-84de-73c200109c24" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ScheduleOfSalesIncentiveProgramTable_ffea0211-c052-452e-abc0-5cd2a7c08c8b" xlink:href="hnst-20211231.xsd#hnst_ScheduleOfSalesIncentiveProgramTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_a4dc0edc-ebee-4aa3-b408-66bcede557b8" xlink:to="loc_hnst_ScheduleOfSalesIncentiveProgramTable_ffea0211-c052-452e-abc0-5cd2a7c08c8b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_fc88b4e4-347d-4682-88ca-203caf88b846" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hnst_ScheduleOfSalesIncentiveProgramTable_ffea0211-c052-452e-abc0-5cd2a7c08c8b" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_fc88b4e4-347d-4682-88ca-203caf88b846" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_fc88b4e4-347d-4682-88ca-203caf88b846_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_fc88b4e4-347d-4682-88ca-203caf88b846" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_fc88b4e4-347d-4682-88ca-203caf88b846_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_76448c17-012b-4e99-9712-f58aad8e1856" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_fc88b4e4-347d-4682-88ca-203caf88b846" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_76448c17-012b-4e99-9712-f58aad8e1856" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_AllowanceSalesIncentiveMember_5653183e-3f69-4c2d-92a0-6e09ad598eff" xlink:href="hnst-20211231.xsd#hnst_AllowanceSalesIncentiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_76448c17-012b-4e99-9712-f58aad8e1856" xlink:to="loc_hnst_AllowanceSalesIncentiveMember_5653183e-3f69-4c2d-92a0-6e09ad598eff" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#RevenueDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="extended" id="i0ce4be1aba064f78b697608ce2298929_RevenueDisaggregationofRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_cf113b9f-739f-4c02-a50b-10d3cd3a5e45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_cfd4c487-ab67-4d44-b1e6-1816e2f500b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_cf113b9f-739f-4c02-a50b-10d3cd3a5e45" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_cfd4c487-ab67-4d44-b1e6-1816e2f500b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_af12e0fe-e537-4da8-83e5-22ee62fa997a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_cf113b9f-739f-4c02-a50b-10d3cd3a5e45" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_af12e0fe-e537-4da8-83e5-22ee62fa997a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_d415760c-25a4-4183-b375-531d61575987" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_af12e0fe-e537-4da8-83e5-22ee62fa997a" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_d415760c-25a4-4183-b375-531d61575987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_d415760c-25a4-4183-b375-531d61575987_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_d415760c-25a4-4183-b375-531d61575987" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_d415760c-25a4-4183-b375-531d61575987_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_bd601ef2-d045-44c0-bca8-24c3e84f7c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_d415760c-25a4-4183-b375-531d61575987" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_bd601ef2-d045-44c0-bca8-24c3e84f7c4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DigitalMember_48809589-e4c9-422e-b019-e8f9e97ef15b" xlink:href="hnst-20211231.xsd#hnst_DigitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_bd601ef2-d045-44c0-bca8-24c3e84f7c4f" xlink:to="loc_hnst_DigitalMember_48809589-e4c9-422e-b019-e8f9e97ef15b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetailMember_62e4e54d-3850-4f0f-9d76-a8f67bf04bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_bd601ef2-d045-44c0-bca8-24c3e84f7c4f" xlink:to="loc_us-gaap_RetailMember_62e4e54d-3850-4f0f-9d76-a8f67bf04bf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_c5b8b0e0-275f-4a97-baf4-d22511276bed" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_af12e0fe-e537-4da8-83e5-22ee62fa997a" xlink:to="loc_srt_ProductOrServiceAxis_c5b8b0e0-275f-4a97-baf4-d22511276bed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c5b8b0e0-275f-4a97-baf4-d22511276bed_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_c5b8b0e0-275f-4a97-baf4-d22511276bed" xlink:to="loc_srt_ProductsAndServicesDomain_c5b8b0e0-275f-4a97-baf4-d22511276bed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_add18683-da88-4aea-8522-e6e51809ae58" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_c5b8b0e0-275f-4a97-baf4-d22511276bed" xlink:to="loc_srt_ProductsAndServicesDomain_add18683-da88-4aea-8522-e6e51809ae58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DiapersAndWipesMember_66acc1a5-c9c7-4d5f-817c-83ca1153efb3" xlink:href="hnst-20211231.xsd#hnst_DiapersAndWipesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_add18683-da88-4aea-8522-e6e51809ae58" xlink:to="loc_hnst_DiapersAndWipesMember_66acc1a5-c9c7-4d5f-817c-83ca1153efb3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SkinAndPersonalCareMember_ee393842-ad49-4f86-a28e-e7524a3ca390" xlink:href="hnst-20211231.xsd#hnst_SkinAndPersonalCareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_add18683-da88-4aea-8522-e6e51809ae58" xlink:to="loc_hnst_SkinAndPersonalCareMember_ee393842-ad49-4f86-a28e-e7524a3ca390" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_HouseholdAndWellnessMember_cf8a15bc-a2e5-423b-877b-edf7e628278d" xlink:href="hnst-20211231.xsd#hnst_HouseholdAndWellnessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_add18683-da88-4aea-8522-e6e51809ae58" xlink:to="loc_hnst_HouseholdAndWellnessMember_cf8a15bc-a2e5-423b-877b-edf7e628278d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RevenueAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#RevenueAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RevenueAdditionalInformationDetails" xlink:type="extended" id="i2c460efefa2c4b468993c90b5e5ce800_RevenueAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNet_f740d55d-e19e-4ca1-ad54-6907a0ef0380" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractWithCustomerAssetNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_us-gaap_ContractWithCustomerAssetNet_f740d55d-e19e-4ca1-ad54-6907a0ef0380" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetPeriod_01d57c6b-60e8-446d-85d5-e97b210f1f39" xlink:href="hnst-20211231.xsd#hnst_ContractWithCustomerAssetPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_hnst_ContractWithCustomerAssetPeriod_01d57c6b-60e8-446d-85d5-e97b210f1f39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetExtensionPeriod_8ba76ad5-cda5-401f-9092-058c5c1533d7" xlink:href="hnst-20211231.xsd#hnst_ContractWithCustomerAssetExtensionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_hnst_ContractWithCustomerAssetExtensionPeriod_8ba76ad5-cda5-401f-9092-058c5c1533d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3d6e2081-6744-4eec-b282-db1484ebfeda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3d6e2081-6744-4eec-b282-db1484ebfeda" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_5d41b001-485b-408e-818b-1b7a888d5cf7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_us-gaap_CostOfRevenue_5d41b001-485b-408e-818b-1b7a888d5cf7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetImpairment_01cbc1d8-9169-4273-8ac6-6996b552e6a1" xlink:href="hnst-20211231.xsd#hnst_ContractWithCustomerAssetImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_hnst_ContractWithCustomerAssetImpairment_01cbc1d8-9169-4273-8ac6-6996b552e6a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetTransportationCreditUtilization_7eb1ba3f-26da-4b45-9c47-50e0bf146705" xlink:href="hnst-20211231.xsd#hnst_ContractWithCustomerAssetTransportationCreditUtilization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_hnst_ContractWithCustomerAssetTransportationCreditUtilization_7eb1ba3f-26da-4b45-9c47-50e0bf146705" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_03179edd-d4c7-435f-8828-307c40f888fb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_abae09dc-e703-42df-ab98-4a414fbf7efe" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_03179edd-d4c7-435f-8828-307c40f888fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_5cef842d-b69d-461f-9569-2477ac365773" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_03179edd-d4c7-435f-8828-307c40f888fb" xlink:to="loc_srt_ProductOrServiceAxis_5cef842d-b69d-461f-9569-2477ac365773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5cef842d-b69d-461f-9569-2477ac365773_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_5cef842d-b69d-461f-9569-2477ac365773" xlink:to="loc_srt_ProductsAndServicesDomain_5cef842d-b69d-461f-9569-2477ac365773_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6a0f6740-176c-4204-8818-89097c8c3610" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_5cef842d-b69d-461f-9569-2477ac365773" xlink:to="loc_srt_ProductsAndServicesDomain_6a0f6740-176c-4204-8818-89097c8c3610" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_TradeAgreementsMember_f44b3377-4c40-4289-a9bd-a688128c34bb" xlink:href="hnst-20211231.xsd#hnst_TradeAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6a0f6740-176c-4204-8818-89097c8c3610" xlink:to="loc_hnst_TradeAgreementsMember_f44b3377-4c40-4289-a9bd-a688128c34bb" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/IntangibleAssetsNetScheduleofIndefiniteAssetsNetDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#IntangibleAssetsNetScheduleofIndefiniteAssetsNetDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/IntangibleAssetsNetScheduleofIndefiniteAssetsNetDetails" xlink:type="extended" id="ib40b1c6b0f4a49f4a1394ba0cea71241_IntangibleAssetsNetScheduleofIndefiniteAssetsNetDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_caf03fb6-518a-424d-8ca5-a669a9c82346" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_fc76498f-cf92-463b-b66a-f632a36903c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_caf03fb6-518a-424d-8ca5-a669a9c82346" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_fc76498f-cf92-463b-b66a-f632a36903c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4650c811-f81c-4452-86aa-8e71a0f89052" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_caf03fb6-518a-424d-8ca5-a669a9c82346" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4650c811-f81c-4452-86aa-8e71a0f89052" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_6b5c46d5-33ff-4f6c-a205-2fa15b350f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_caf03fb6-518a-424d-8ca5-a669a9c82346" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_6b5c46d5-33ff-4f6c-a205-2fa15b350f9a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_b6c896af-dd0a-4192-a5c3-615a7d3362e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_caf03fb6-518a-424d-8ca5-a669a9c82346" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_b6c896af-dd0a-4192-a5c3-615a7d3362e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06d5b621-1dfa-47e8-8083-5acc60fed6d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_b6c896af-dd0a-4192-a5c3-615a7d3362e5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06d5b621-1dfa-47e8-8083-5acc60fed6d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_06d5b621-1dfa-47e8-8083-5acc60fed6d5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06d5b621-1dfa-47e8-8083-5acc60fed6d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_06d5b621-1dfa-47e8-8083-5acc60fed6d5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8494ad51-a28b-43fb-a083-cc5959d1bdfb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_06d5b621-1dfa-47e8-8083-5acc60fed6d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8494ad51-a28b-43fb-a083-cc5959d1bdfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_97969d94-7c61-4da3-a93e-ec9adeb00453" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8494ad51-a28b-43fb-a083-cc5959d1bdfb" xlink:to="loc_us-gaap_TradeNamesMember_97969d94-7c61-4da3-a93e-ec9adeb00453" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternetDomainNamesMember_6ece9f20-f4e6-472a-8adf-942011a60470" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InternetDomainNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8494ad51-a28b-43fb-a083-cc5959d1bdfb" xlink:to="loc_us-gaap_InternetDomainNamesMember_6ece9f20-f4e6-472a-8adf-942011a60470" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/IntangibleAssetsNetAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#IntangibleAssetsNetAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/IntangibleAssetsNetAdditionalInformationDetails" xlink:type="extended" id="id964673d223844429382a16865bcf87f_IntangibleAssetsNetAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b5ddb558-c21f-484d-aaf2-7b5dc1babb42" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_fbb2d7a5-0bc9-4d61-9648-53539dff1ef7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b5ddb558-c21f-484d-aaf2-7b5dc1babb42" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1_fbb2d7a5-0bc9-4d61-9648-53539dff1ef7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_d991fbc2-99c7-4e98-8eae-0fae3f1b37e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b5ddb558-c21f-484d-aaf2-7b5dc1babb42" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_d991fbc2-99c7-4e98-8eae-0fae3f1b37e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5ef133fc-4682-467c-ab4c-e1d1a7e187cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_b5ddb558-c21f-484d-aaf2-7b5dc1babb42" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5ef133fc-4682-467c-ab4c-e1d1a7e187cd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f36fe66e-e2a4-4645-8c0f-e66f5a5f7b53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5ef133fc-4682-467c-ab4c-e1d1a7e187cd" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f36fe66e-e2a4-4645-8c0f-e66f5a5f7b53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f36fe66e-e2a4-4645-8c0f-e66f5a5f7b53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f36fe66e-e2a4-4645-8c0f-e66f5a5f7b53" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_f36fe66e-e2a4-4645-8c0f-e66f5a5f7b53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_28dba0bb-0241-4a97-aa43-270e8b614c50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_f36fe66e-e2a4-4645-8c0f-e66f5a5f7b53" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_28dba0bb-0241-4a97-aa43-270e8b614c50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_bc6ba84c-079f-4aed-a78f-0dcda5d96662" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_28dba0bb-0241-4a97-aa43-270e8b614c50" xlink:to="loc_us-gaap_TradeNamesMember_bc6ba84c-079f-4aed-a78f-0dcda5d96662" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternetDomainNamesMember_d8599e27-b56c-41c5-a3c8-c1b5a0d6d7fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InternetDomainNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_28dba0bb-0241-4a97-aa43-270e8b614c50" xlink:to="loc_us-gaap_InternetDomainNamesMember_d8599e27-b56c-41c5-a3c8-c1b5a0d6d7fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_82929f37-efc3-473d-9b35-6ef75b06c956" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_5ef133fc-4682-467c-ab4c-e1d1a7e187cd" xlink:to="loc_srt_RangeAxis_82929f37-efc3-473d-9b35-6ef75b06c956" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_82929f37-efc3-473d-9b35-6ef75b06c956_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_82929f37-efc3-473d-9b35-6ef75b06c956" xlink:to="loc_srt_RangeMember_82929f37-efc3-473d-9b35-6ef75b06c956_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_553a2633-4816-4ebb-9afb-77bafe567f7c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_82929f37-efc3-473d-9b35-6ef75b06c956" xlink:to="loc_srt_RangeMember_553a2633-4816-4ebb-9afb-77bafe567f7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_912d71fa-c624-42f0-b320-8716e89ecb7d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_553a2633-4816-4ebb-9afb-77bafe567f7c" xlink:to="loc_srt_WeightedAverageMember_912d71fa-c624-42f0-b320-8716e89ecb7d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/PropertyandEquipmentNetComponentsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#PropertyandEquipmentNetComponentsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/PropertyandEquipmentNetComponentsDetails" xlink:type="extended" id="i9ad6997bc0e744a686cd52abf06f23f9_PropertyandEquipmentNetComponentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e7186519-bbe7-44c3-b906-aaf45f2b03e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_8fa54f11-97ec-4b63-b690-6525c4772f02" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e7186519-bbe7-44c3-b906-aaf45f2b03e1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_8fa54f11-97ec-4b63-b690-6525c4772f02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_370ad1d5-c2bb-4eb5-ae60-fca9af083c63" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e7186519-bbe7-44c3-b906-aaf45f2b03e1" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_370ad1d5-c2bb-4eb5-ae60-fca9af083c63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_17dc1473-a3f2-4e23-9861-6108ba28938f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e7186519-bbe7-44c3-b906-aaf45f2b03e1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_17dc1473-a3f2-4e23-9861-6108ba28938f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2aac1844-45f8-486b-90ab-5c1d47997ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e7186519-bbe7-44c3-b906-aaf45f2b03e1" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2aac1844-45f8-486b-90ab-5c1d47997ecd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7df1dd94-bcf3-4ddd-b15b-490ddf51ad53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2aac1844-45f8-486b-90ab-5c1d47997ecd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7df1dd94-bcf3-4ddd-b15b-490ddf51ad53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_7df1dd94-bcf3-4ddd-b15b-490ddf51ad53_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7df1dd94-bcf3-4ddd-b15b-490ddf51ad53" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_7df1dd94-bcf3-4ddd-b15b-490ddf51ad53_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_7df1dd94-bcf3-4ddd-b15b-490ddf51ad53" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_993d8fcb-b4ea-4ccf-aef9-511dcbc5935a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_993d8fcb-b4ea-4ccf-aef9-511dcbc5935a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ComputerAndOfficeEquipmentMember_162c3ff0-dce3-47be-88bc-6450637fe5ee" xlink:href="hnst-20211231.xsd#hnst_ComputerAndOfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:to="loc_hnst_ComputerAndOfficeEquipmentMember_162c3ff0-dce3-47be-88bc-6450637fe5ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_34385351-f303-4ffe-b320-02103e58b61f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_34385351-f303-4ffe-b320-02103e58b61f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_fa6b8f1e-6842-4d43-ae9f-c372a9976834" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_fa6b8f1e-6842-4d43-ae9f-c372a9976834" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdsAndLeaseholdImprovementsMember_91b392a4-7fe8-4038-8cb4-6619027b9fa5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeaseholdsAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:to="loc_us-gaap_LeaseholdsAndLeaseholdImprovementsMember_91b392a4-7fe8-4038-8cb4-6619027b9fa5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_a4a357e0-6c8c-4db6-b9b5-f48f8bc69364" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_211051cc-9c05-4408-864b-2c066f4339cb" xlink:to="loc_us-gaap_BuildingMember_a4a357e0-6c8c-4db6-b9b5-f48f8bc69364" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/PropertyandEquipmentNetAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#PropertyandEquipmentNetAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/PropertyandEquipmentNetAdditionalInformationDetails" xlink:type="extended" id="i9045f2f87aad47af89e8536e8955aabe_PropertyandEquipmentNetAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3ce06b12-08f8-41d4-b219-e0a50ebae3aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasedAssetsGross_d23c9fe7-8083-4503-a2ce-2beed21d7ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasedAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3ce06b12-08f8-41d4-b219-e0a50ebae3aa" xlink:to="loc_us-gaap_CapitalLeasedAssetsGross_d23c9fe7-8083-4503-a2ce-2beed21d7ec2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesIncomeStatementAmortizationExpense_c91b7716-2fe5-4b6c-96ef-747e8a74d074" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesIncomeStatementAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3ce06b12-08f8-41d4-b219-e0a50ebae3aa" xlink:to="loc_us-gaap_CapitalLeasesIncomeStatementAmortizationExpense_c91b7716-2fe5-4b6c-96ef-747e8a74d074" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_65b47f6a-4279-410e-9cd2-ce4d366dffca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_3ce06b12-08f8-41d4-b219-e0a50ebae3aa" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_65b47f6a-4279-410e-9cd2-ce4d366dffca" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_70a0c2f7-1790-4e47-9ee4-6f2b99fc8437" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_65b47f6a-4279-410e-9cd2-ce4d366dffca" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_70a0c2f7-1790-4e47-9ee4-6f2b99fc8437" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_70a0c2f7-1790-4e47-9ee4-6f2b99fc8437_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_70a0c2f7-1790-4e47-9ee4-6f2b99fc8437" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_70a0c2f7-1790-4e47-9ee4-6f2b99fc8437_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1f1c807-d17c-4e2e-ac78-054dca94adbc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_70a0c2f7-1790-4e47-9ee4-6f2b99fc8437" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1f1c807-d17c-4e2e-ac78-054dca94adbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsHeldUnderCapitalLeasesMember_9f5e53e7-bc6e-48e9-8b7e-303a4951600b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsHeldUnderCapitalLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1f1c807-d17c-4e2e-ac78-054dca94adbc" xlink:to="loc_us-gaap_AssetsHeldUnderCapitalLeasesMember_9f5e53e7-bc6e-48e9-8b7e-303a4951600b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/PropertyandEquipmentNetScheduleofDepreciationExpenseDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#PropertyandEquipmentNetScheduleofDepreciationExpenseDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/PropertyandEquipmentNetScheduleofDepreciationExpenseDetails" xlink:type="extended" id="ib635492857a14b76b421ae4f8d5055ab_PropertyandEquipmentNetScheduleofDepreciationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_8acabcaa-e482-41ae-a757-484cffc67c89" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_03c74dd1-2cfe-42c3-9abc-455bba64ab3a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_8acabcaa-e482-41ae-a757-484cffc67c89" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_03c74dd1-2cfe-42c3-9abc-455bba64ab3a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_07b1844d-0228-4a4e-a06e-918fbfbfa34d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_8acabcaa-e482-41ae-a757-484cffc67c89" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_07b1844d-0228-4a4e-a06e-918fbfbfa34d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_1f95d904-32b4-4914-9366-37dfaa04e457" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_07b1844d-0228-4a4e-a06e-918fbfbfa34d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_1f95d904-32b4-4914-9366-37dfaa04e457" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1f95d904-32b4-4914-9366-37dfaa04e457_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_1f95d904-32b4-4914-9366-37dfaa04e457" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1f95d904-32b4-4914-9366-37dfaa04e457_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_5c8b144f-2dfa-4782-a4ad-4068c26238aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_1f95d904-32b4-4914-9366-37dfaa04e457" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_5c8b144f-2dfa-4782-a4ad-4068c26238aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_51e55545-cb80-4c7c-b13b-3f82be699704" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5c8b144f-2dfa-4782-a4ad-4068c26238aa" xlink:to="loc_us-gaap_CostOfSalesMember_51e55545-cb80-4c7c-b13b-3f82be699704" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_64132914-6d2c-4f51-8888-6ca742dcccd3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5c8b144f-2dfa-4782-a4ad-4068c26238aa" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_64132914-6d2c-4f51-8888-6ca742dcccd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_317542e2-0349-4cac-ae4e-e47934dcc126" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5c8b144f-2dfa-4782-a4ad-4068c26238aa" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_317542e2-0349-4cac-ae4e-e47934dcc126" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_9195fe5c-7818-4e34-a0ec-487b3e11c842" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_07b1844d-0228-4a4e-a06e-918fbfbfa34d" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_9195fe5c-7818-4e34-a0ec-487b3e11c842" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9195fe5c-7818-4e34-a0ec-487b3e11c842_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_9195fe5c-7818-4e34-a0ec-487b3e11c842" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_9195fe5c-7818-4e34-a0ec-487b3e11c842_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_2b0b9ac3-21e2-4a71-9413-08cc0445f8e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_9195fe5c-7818-4e34-a0ec-487b3e11c842" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_2b0b9ac3-21e2-4a71-9413-08cc0445f8e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentMember_c7701cd0-b77a-42e8-8372-fe60305d579c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_2b0b9ac3-21e2-4a71-9413-08cc0445f8e5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentMember_c7701cd0-b77a-42e8-8372-fe60305d579c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#InvestmentsAvailableforSaleInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="extended" id="i54e7fac37e2c4cac8689a8e20e2eab7b_InvestmentsAvailableforSaleInvestmentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0e645edf-a59b-42b4-945f-f43243ab7924" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_ec3441e9-8bbe-4ebf-9806-153409126bad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0e645edf-a59b-42b4-945f-f43243ab7924" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_ec3441e9-8bbe-4ebf-9806-153409126bad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_44585505-c843-4846-9285-29f079ef3f0c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0e645edf-a59b-42b4-945f-f43243ab7924" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_44585505-c843-4846-9285-29f079ef3f0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_fc59ce3f-b572-48a0-aa4a-4f8681e1610d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0e645edf-a59b-42b4-945f-f43243ab7924" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_fc59ce3f-b572-48a0-aa4a-4f8681e1610d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_6f8e1532-2494-490a-bc04-8399b5cfe6ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0e645edf-a59b-42b4-945f-f43243ab7924" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_6f8e1532-2494-490a-bc04-8399b5cfe6ac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3301c708-12ef-4eda-8ab9-f3d2abe9acac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_0e645edf-a59b-42b4-945f-f43243ab7924" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3301c708-12ef-4eda-8ab9-f3d2abe9acac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_f3875c0c-2214-4562-8684-1978a71ebe18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_3301c708-12ef-4eda-8ab9-f3d2abe9acac" xlink:to="loc_us-gaap_FinancialInstrumentAxis_f3875c0c-2214-4562-8684-1978a71ebe18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f3875c0c-2214-4562-8684-1978a71ebe18_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_f3875c0c-2214-4562-8684-1978a71ebe18" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f3875c0c-2214-4562-8684-1978a71ebe18_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e4c5f689-0db0-4a67-9c59-9594d2f4c293" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_f3875c0c-2214-4562-8684-1978a71ebe18" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e4c5f689-0db0-4a67-9c59-9594d2f4c293" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_b3b01365-9da9-4526-ac99-f338431d5c49" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e4c5f689-0db0-4a67-9c59-9594d2f4c293" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_b3b01365-9da9-4526-ac99-f338431d5c49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_5c67056f-cb89-4253-887b-c0a3ccdc6a3d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e4c5f689-0db0-4a67-9c59-9594d2f4c293" xlink:to="loc_us-gaap_CommercialPaperMember_5c67056f-cb89-4253-887b-c0a3ccdc6a3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_2f5e584c-8605-424b-a90e-91757f37162c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e4c5f689-0db0-4a67-9c59-9594d2f4c293" xlink:to="loc_us-gaap_CertificatesOfDepositMember_2f5e584c-8605-424b-a90e-91757f37162c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryAndGovernmentMember_be5f695b-3527-4358-b0e4-a1d2ddcd40d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USTreasuryAndGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e4c5f689-0db0-4a67-9c59-9594d2f4c293" xlink:to="loc_us-gaap_USTreasuryAndGovernmentMember_be5f695b-3527-4358-b0e4-a1d2ddcd40d7" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#FairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/FairValueMeasurementsDetails" xlink:type="extended" id="if9f7bdac9b654ffc9be7c2d1bb934dd0_FairValueMeasurementsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0605a1ec-dafe-4c29-a8d1-07aa0ef509a9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_5bc1262c-7ff6-4eb4-b4c5-afae4d3e00d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0605a1ec-dafe-4c29-a8d1-07aa0ef509a9" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_5bc1262c-7ff6-4eb4-b4c5-afae4d3e00d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_276a5524-1744-4df0-b051-80e17dcf68f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0605a1ec-dafe-4c29-a8d1-07aa0ef509a9" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_276a5524-1744-4df0-b051-80e17dcf68f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_087f8344-3154-488b-901e-e82a20f9039d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0605a1ec-dafe-4c29-a8d1-07aa0ef509a9" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_087f8344-3154-488b-901e-e82a20f9039d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5ecc3fc2-0c51-4c55-a9d3-b8e868cd27fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0605a1ec-dafe-4c29-a8d1-07aa0ef509a9" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5ecc3fc2-0c51-4c55-a9d3-b8e868cd27fc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1cbb3c4b-0d14-44f6-8a3e-506989b2b0c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5ecc3fc2-0c51-4c55-a9d3-b8e868cd27fc" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1cbb3c4b-0d14-44f6-8a3e-506989b2b0c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1cbb3c4b-0d14-44f6-8a3e-506989b2b0c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1cbb3c4b-0d14-44f6-8a3e-506989b2b0c1" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1cbb3c4b-0d14-44f6-8a3e-506989b2b0c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1f56a805-00a6-42fc-8d64-bb7c85e8bbda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1cbb3c4b-0d14-44f6-8a3e-506989b2b0c1" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1f56a805-00a6-42fc-8d64-bb7c85e8bbda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_27635af6-5670-458e-b7e4-53234df4e658" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_1f56a805-00a6-42fc-8d64-bb7c85e8bbda" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_27635af6-5670-458e-b7e4-53234df4e658" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68efbf5f-58ea-4315-a9ce-93ec52b48fe0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5ecc3fc2-0c51-4c55-a9d3-b8e868cd27fc" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68efbf5f-58ea-4315-a9ce-93ec52b48fe0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68efbf5f-58ea-4315-a9ce-93ec52b48fe0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68efbf5f-58ea-4315-a9ce-93ec52b48fe0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68efbf5f-58ea-4315-a9ce-93ec52b48fe0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8c6d7517-2092-4456-bfcd-27b7c5c0c09d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_68efbf5f-58ea-4315-a9ce-93ec52b48fe0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8c6d7517-2092-4456-bfcd-27b7c5c0c09d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_a9cf4b6a-5693-4a73-a9c4-623653a63df1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8c6d7517-2092-4456-bfcd-27b7c5c0c09d" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_a9cf4b6a-5693-4a73-a9c4-623653a63df1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_3d158083-be5b-49c0-ab00-4d54101b02cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8c6d7517-2092-4456-bfcd-27b7c5c0c09d" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_3d158083-be5b-49c0-ab00-4d54101b02cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_96794f41-df8f-4a18-8323-6e726067f892" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8c6d7517-2092-4456-bfcd-27b7c5c0c09d" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_96794f41-df8f-4a18-8323-6e726067f892" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_b4afbc44-b6ef-46fd-a06f-dfd9b5b84af3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5ecc3fc2-0c51-4c55-a9d3-b8e868cd27fc" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_b4afbc44-b6ef-46fd-a06f-dfd9b5b84af3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_b4afbc44-b6ef-46fd-a06f-dfd9b5b84af3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_b4afbc44-b6ef-46fd-a06f-dfd9b5b84af3" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_b4afbc44-b6ef-46fd-a06f-dfd9b5b84af3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_bfb64d90-1070-4746-b4c6-afad338d85da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_b4afbc44-b6ef-46fd-a06f-dfd9b5b84af3" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_bfb64d90-1070-4746-b4c6-afad338d85da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_e97b5818-13db-4bdd-8c12-c8854bf48cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_bfb64d90-1070-4746-b4c6-afad338d85da" xlink:to="loc_us-gaap_MoneyMarketFundsMember_e97b5818-13db-4bdd-8c12-c8854bf48cd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_a39e8514-79f4-4609-bf89-63ecbb3d27e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5ecc3fc2-0c51-4c55-a9d3-b8e868cd27fc" xlink:to="loc_us-gaap_FinancialInstrumentAxis_a39e8514-79f4-4609-bf89-63ecbb3d27e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a39e8514-79f4-4609-bf89-63ecbb3d27e0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_a39e8514-79f4-4609-bf89-63ecbb3d27e0" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a39e8514-79f4-4609-bf89-63ecbb3d27e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4b1eea0-1325-4b01-8fac-b9e349a6ab5b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_a39e8514-79f4-4609-bf89-63ecbb3d27e0" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4b1eea0-1325-4b01-8fac-b9e349a6ab5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_b6e7ade2-753c-4631-98f5-43caaa29d070" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4b1eea0-1325-4b01-8fac-b9e349a6ab5b" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_b6e7ade2-753c-4631-98f5-43caaa29d070" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_56ffd3f0-7d09-40a5-b011-bac25b07ee1e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4b1eea0-1325-4b01-8fac-b9e349a6ab5b" xlink:to="loc_us-gaap_CommercialPaperMember_56ffd3f0-7d09-40a5-b011-bac25b07ee1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_5d5f97a3-bde4-4900-8da7-d2da71c29602" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CertificatesOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4b1eea0-1325-4b01-8fac-b9e349a6ab5b" xlink:to="loc_us-gaap_CertificatesOfDepositMember_5d5f97a3-bde4-4900-8da7-d2da71c29602" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryAndGovernmentMember_6252a873-821d-4edb-a11b-9df25b4f6e3c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USTreasuryAndGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b4b1eea0-1325-4b01-8fac-b9e349a6ab5b" xlink:to="loc_us-gaap_USTreasuryAndGovernmentMember_6252a873-821d-4edb-a11b-9df25b4f6e3c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/CreditFacilitiesDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#CreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/CreditFacilitiesDetails" xlink:type="extended" id="i386461b0713a40a6bfa1d11598eeccdb_CreditFacilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_cba477d1-f8a4-44b9-964d-5b2126308fb5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_LineOfCredit_cba477d1-f8a4-44b9-964d-5b2126308fb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_b811886f-3858-4b03-8b28-320e8244a565" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_RestrictedCash_b811886f-3858-4b03-8b28-320e8244a565" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_21426642-8659-4e1a-9605-54f7c5ff41d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_21426642-8659-4e1a-9605-54f7c5ff41d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_ea0a2549-a14e-4364-8919-698c133e76b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_ea0a2549-a14e-4364-8919-698c133e76b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_87eb704f-12fd-4b70-821f-8007f5f6d55f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_87eb704f-12fd-4b70-821f-8007f5f6d55f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DebtInstrumentInterestRateBase_fd297f64-f1f2-4464-b32a-f696b0261ff6" xlink:href="hnst-20211231.xsd#hnst_DebtInstrumentInterestRateBase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_hnst_DebtInstrumentInterestRateBase_fd297f64-f1f2-4464-b32a-f696b0261ff6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_edec0ebc-5fb0-4c3f-bd11-c6928fb9473e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_edec0ebc-5fb0-4c3f-bd11-c6928fb9473e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DebtInstrumentCovenantLeverageRatioMaximum_cb7daf6f-7975-49aa-a1b9-45d14c65190e" xlink:href="hnst-20211231.xsd#hnst_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_hnst_DebtInstrumentCovenantLeverageRatioMaximum_cb7daf6f-7975-49aa-a1b9-45d14c65190e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0e5896aa-a54a-426a-9305-c59d46e8fa79" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_7b68fcef-d168-47e5-a519-ed1c1d1f80e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_7b68fcef-d168-47e5-a519-ed1c1d1f80e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7b68fcef-d168-47e5-a519-ed1c1d1f80e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7b68fcef-d168-47e5-a519-ed1c1d1f80e3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7b68fcef-d168-47e5-a519-ed1c1d1f80e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bad1bd4f-f0d9-4297-88d7-df9fb2a4c064" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7b68fcef-d168-47e5-a519-ed1c1d1f80e3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bad1bd4f-f0d9-4297-88d7-df9fb2a4c064" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_47a1c4db-954e-49e7-b9c2-11697fe038da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bad1bd4f-f0d9-4297-88d7-df9fb2a4c064" xlink:to="loc_us-gaap_LineOfCreditMember_47a1c4db-954e-49e7-b9c2-11697fe038da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_3a20eddc-c1cc-4be3-a66f-a7731df9187e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:to="loc_us-gaap_DebtInstrumentAxis_3a20eddc-c1cc-4be3-a66f-a7731df9187e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3a20eddc-c1cc-4be3-a66f-a7731df9187e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_3a20eddc-c1cc-4be3-a66f-a7731df9187e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3a20eddc-c1cc-4be3-a66f-a7731df9187e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3de8ae31-a594-4453-955d-acf0ff2da965" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_3a20eddc-c1cc-4be3-a66f-a7731df9187e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3de8ae31-a594-4453-955d-acf0ff2da965" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_AssetBackedLoanFacilityMember_141ea633-21d6-4ff6-ab74-53caeb23c4c3" xlink:href="hnst-20211231.xsd#hnst_AssetBackedLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_3de8ae31-a594-4453-955d-acf0ff2da965" xlink:to="loc_hnst_AssetBackedLoanFacilityMember_141ea633-21d6-4ff6-ab74-53caeb23c4c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021CreditFacilityMember_6691fb56-4241-4ac8-a987-0769cb901c2b" xlink:href="hnst-20211231.xsd#hnst_A2021CreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_3de8ae31-a594-4453-955d-acf0ff2da965" xlink:to="loc_hnst_A2021CreditFacilityMember_6691fb56-4241-4ac8-a987-0769cb901c2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_995e1491-0080-4c8f-990b-8513725636b6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:to="loc_us-gaap_CreditFacilityAxis_995e1491-0080-4c8f-990b-8513725636b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_995e1491-0080-4c8f-990b-8513725636b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_995e1491-0080-4c8f-990b-8513725636b6" xlink:to="loc_us-gaap_CreditFacilityDomain_995e1491-0080-4c8f-990b-8513725636b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_f1a6bd39-49c6-4a6a-b9f0-ae0de4c36a15" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_995e1491-0080-4c8f-990b-8513725636b6" xlink:to="loc_us-gaap_CreditFacilityDomain_f1a6bd39-49c6-4a6a-b9f0-ae0de4c36a15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_4d1def1b-7ec7-435a-8eb3-ea6f0425c554" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_f1a6bd39-49c6-4a6a-b9f0-ae0de4c36a15" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_4d1def1b-7ec7-435a-8eb3-ea6f0425c554" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_cf206577-e0c9-4bb2-a77e-34ffc27143b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_f1a6bd39-49c6-4a6a-b9f0-ae0de4c36a15" xlink:to="loc_us-gaap_LetterOfCreditMember_cf206577-e0c9-4bb2-a77e-34ffc27143b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_adb6749e-629d-4016-bc79-ec58ca76075c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_adb6749e-629d-4016-bc79-ec58ca76075c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_adb6749e-629d-4016-bc79-ec58ca76075c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_adb6749e-629d-4016-bc79-ec58ca76075c" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_adb6749e-629d-4016-bc79-ec58ca76075c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_b3bd6f87-9d70-46b5-a0e8-941e6f53d7c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_adb6749e-629d-4016-bc79-ec58ca76075c" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_b3bd6f87-9d70-46b5-a0e8-941e6f53d7c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_JPMorganChaseBankMember_0864fd09-3c49-4efc-b8c2-96d7f2295698" xlink:href="hnst-20211231.xsd#hnst_JPMorganChaseBankMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_b3bd6f87-9d70-46b5-a0e8-941e6f53d7c2" xlink:to="loc_hnst_JPMorganChaseBankMember_0864fd09-3c49-4efc-b8c2-96d7f2295698" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c8fa6e0e-05bf-4694-8f95-b1279b69d0fd" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:to="loc_srt_RangeAxis_c8fa6e0e-05bf-4694-8f95-b1279b69d0fd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c8fa6e0e-05bf-4694-8f95-b1279b69d0fd_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c8fa6e0e-05bf-4694-8f95-b1279b69d0fd" xlink:to="loc_srt_RangeMember_c8fa6e0e-05bf-4694-8f95-b1279b69d0fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a2b37429-4d83-45a2-9773-7f59a27b118b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c8fa6e0e-05bf-4694-8f95-b1279b69d0fd" xlink:to="loc_srt_RangeMember_a2b37429-4d83-45a2-9773-7f59a27b118b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b85b0432-5197-470c-98b5-4ba45341799d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a2b37429-4d83-45a2-9773-7f59a27b118b" xlink:to="loc_srt_MinimumMember_b85b0432-5197-470c-98b5-4ba45341799d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_b5160bbf-7a8c-40c4-8eea-0b50539cfa3e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_f3fe886d-8026-4294-83cf-6d68cb66a870" xlink:to="loc_us-gaap_VariableRateAxis_b5160bbf-7a8c-40c4-8eea-0b50539cfa3e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_b5160bbf-7a8c-40c4-8eea-0b50539cfa3e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_b5160bbf-7a8c-40c4-8eea-0b50539cfa3e" xlink:to="loc_us-gaap_VariableRateDomain_b5160bbf-7a8c-40c4-8eea-0b50539cfa3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_d8625ca5-161a-4346-8460-6dac18c7aed3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_b5160bbf-7a8c-40c4-8eea-0b50539cfa3e" xlink:to="loc_us-gaap_VariableRateDomain_d8625ca5-161a-4346-8460-6dac18c7aed3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_ba542ef8-eb62-4207-a191-db077f0b0994" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d8625ca5-161a-4346-8460-6dac18c7aed3" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_ba542ef8-eb62-4207-a191-db077f0b0994" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_73bfa676-2535-4090-940c-beed1bf1c4fe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d8625ca5-161a-4346-8460-6dac18c7aed3" xlink:to="loc_us-gaap_BaseRateMember_73bfa676-2535-4090-940c-beed1bf1c4fe" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RedeemableConvertiblePreferredStockandStockholdersDeficitAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#RedeemableConvertiblePreferredStockandStockholdersDeficitAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RedeemableConvertiblePreferredStockandStockholdersDeficitAdditionalInformationDetails" xlink:type="extended" id="ibf673291b5f445449036d00dbf743079_RedeemableConvertiblePreferredStockandStockholdersDeficitAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_fdd8b112-f9d5-4f65-9b19-6837fa308cc1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_fdd8b112-f9d5-4f65-9b19-6837fa308cc1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_2234efb5-e05f-4c05-ac28-649dfa949705" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_2234efb5-e05f-4c05-ac28-649dfa949705" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_5aef466a-2e77-4536-9977-bd695496c762" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_5aef466a-2e77-4536-9977-bd695496c762" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_c1fa35dd-d00f-4feb-870b-741f8283ca75" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_c1fa35dd-d00f-4feb-870b-741f8283ca75" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_bd41add2-becb-488c-8a43-b95539e94ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_bd41add2-becb-488c-8a43-b95539e94ad3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_b8e83add-ffed-4fd0-b86a-f3010216a821" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_b8e83add-ffed-4fd0-b86a-f3010216a821" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_TemporaryEquitySharesAvailableForIssuance_731664dd-7147-4e90-bb76-5f6acb31578b" xlink:href="hnst-20211231.xsd#hnst_TemporaryEquitySharesAvailableForIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_hnst_TemporaryEquitySharesAvailableForIssuance_731664dd-7147-4e90-bb76-5f6acb31578b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityByClassOfStockTable_44ba4198-b451-41b3-b8a6-ed6d5468b428" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityByClassOfStockTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TemporaryEquityLineItems_4bf9cf58-a73d-4c1e-a029-c5a48f98700d" xlink:to="loc_us-gaap_TemporaryEquityByClassOfStockTable_44ba4198-b451-41b3-b8a6-ed6d5468b428" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_04ceea66-cd62-4d90-baa8-c0a03be5944e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_44ba4198-b451-41b3-b8a6-ed6d5468b428" xlink:to="loc_us-gaap_StatementClassOfStockAxis_04ceea66-cd62-4d90-baa8-c0a03be5944e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_04ceea66-cd62-4d90-baa8-c0a03be5944e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_04ceea66-cd62-4d90-baa8-c0a03be5944e" xlink:to="loc_us-gaap_ClassOfStockDomain_04ceea66-cd62-4d90-baa8-c0a03be5944e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_04ceea66-cd62-4d90-baa8-c0a03be5944e" xlink:to="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesARedeemableConvertiblePreferredStockMember_85cf3f47-8f51-4597-8523-5f5327381c83" xlink:href="hnst-20211231.xsd#hnst_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesARedeemableConvertiblePreferredStockMember_85cf3f47-8f51-4597-8523-5f5327381c83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesA1RedeemableConvertiblePreferredStockMember_04908f75-67ce-4a93-b1ec-670d83095e30" xlink:href="hnst-20211231.xsd#hnst_SeriesA1RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesA1RedeemableConvertiblePreferredStockMember_04908f75-67ce-4a93-b1ec-670d83095e30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesBRedeemableConvertiblePreferredStockMember_a409f595-88ef-429d-b7de-30441b897269" xlink:href="hnst-20211231.xsd#hnst_SeriesBRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesBRedeemableConvertiblePreferredStockMember_a409f595-88ef-429d-b7de-30441b897269" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesCRedeemableConvertiblePreferredStockMember_d3c0c014-f888-44a3-8cbe-77a50c56150b" xlink:href="hnst-20211231.xsd#hnst_SeriesCRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesCRedeemableConvertiblePreferredStockMember_d3c0c014-f888-44a3-8cbe-77a50c56150b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesDRedeemableConvertiblePreferredStockMember_90f7a170-198c-40ab-bf1e-1f15bf413cfe" xlink:href="hnst-20211231.xsd#hnst_SeriesDRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesDRedeemableConvertiblePreferredStockMember_90f7a170-198c-40ab-bf1e-1f15bf413cfe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesERedeemableConvertiblePreferredStockMember_dc64b231-b052-486d-8f21-51071492977c" xlink:href="hnst-20211231.xsd#hnst_SeriesERedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesERedeemableConvertiblePreferredStockMember_dc64b231-b052-486d-8f21-51071492977c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesFRedeemableConvertiblePreferredStockMember_5caab1fd-e506-4002-a1ad-d1cbec03dbd3" xlink:href="hnst-20211231.xsd#hnst_SeriesFRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b218f376-bd98-4148-b818-84ac6a79bcc1" xlink:to="loc_hnst_SeriesFRedeemableConvertiblePreferredStockMember_5caab1fd-e506-4002-a1ad-d1cbec03dbd3" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RedeemableConvertiblePreferredStockandStockholdersDeficitSummaryofRedeemableConvertiblePreferredStockInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#RedeemableConvertiblePreferredStockandStockholdersDeficitSummaryofRedeemableConvertiblePreferredStockInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RedeemableConvertiblePreferredStockandStockholdersDeficitSummaryofRedeemableConvertiblePreferredStockInformationDetails" xlink:type="extended" id="ie4c59ff8a4c74cf29a11f23114bc22c9_RedeemableConvertiblePreferredStockandStockholdersDeficitSummaryofRedeemableConvertiblePreferredStockInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesAuthorized_26bccb45-cda1-47f1-911b-54813c3400ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:to="loc_us-gaap_TemporaryEquitySharesAuthorized_26bccb45-cda1-47f1-911b-54813c3400ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_47be622f-7454-4ee2-be1e-174303666a7d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_47be622f-7454-4ee2-be1e-174303666a7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_45d03598-75ff-4158-ae1e-4d368fa71fdc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_45d03598-75ff-4158-ae1e-4d368fa71fdc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_a1642004-f82f-4c3d-bfa5-6a898f99055b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_a1642004-f82f-4c3d-bfa5-6a898f99055b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLiquidationPreference_5f231f2b-1a47-4ee9-88a1-0508b9d8ac0a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityLiquidationPreference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:to="loc_us-gaap_TemporaryEquityLiquidationPreference_5f231f2b-1a47-4ee9-88a1-0508b9d8ac0a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityByClassOfStockTable_eddacbbe-2821-4c8b-9642-d95f79e16151" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityByClassOfStockTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TemporaryEquityLineItems_21641163-f526-4a39-8cc7-43b517ff3e6d" xlink:to="loc_us-gaap_TemporaryEquityByClassOfStockTable_eddacbbe-2821-4c8b-9642-d95f79e16151" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_2fc1b420-a9dc-4ba0-acdb-a3836f745e3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_eddacbbe-2821-4c8b-9642-d95f79e16151" xlink:to="loc_us-gaap_StatementClassOfStockAxis_2fc1b420-a9dc-4ba0-acdb-a3836f745e3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_2fc1b420-a9dc-4ba0-acdb-a3836f745e3f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2fc1b420-a9dc-4ba0-acdb-a3836f745e3f" xlink:to="loc_us-gaap_ClassOfStockDomain_2fc1b420-a9dc-4ba0-acdb-a3836f745e3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_2fc1b420-a9dc-4ba0-acdb-a3836f745e3f" xlink:to="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesARedeemableConvertiblePreferredStockMember_66194fa1-070b-4cf4-a319-7bcb61f082e8" xlink:href="hnst-20211231.xsd#hnst_SeriesARedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesARedeemableConvertiblePreferredStockMember_66194fa1-070b-4cf4-a319-7bcb61f082e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesA1RedeemableConvertiblePreferredStockMember_42a2a2c4-b64a-4156-907e-23481b9cafec" xlink:href="hnst-20211231.xsd#hnst_SeriesA1RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesA1RedeemableConvertiblePreferredStockMember_42a2a2c4-b64a-4156-907e-23481b9cafec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesBRedeemableConvertiblePreferredStockMember_b7bc95db-7280-4255-9878-7327f6fe7ef7" xlink:href="hnst-20211231.xsd#hnst_SeriesBRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesBRedeemableConvertiblePreferredStockMember_b7bc95db-7280-4255-9878-7327f6fe7ef7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesCRedeemableConvertiblePreferredStockMember_a48d07ee-7320-4d7f-8827-b20a16d65230" xlink:href="hnst-20211231.xsd#hnst_SeriesCRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesCRedeemableConvertiblePreferredStockMember_a48d07ee-7320-4d7f-8827-b20a16d65230" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesDRedeemableConvertiblePreferredStockMember_9670feab-c060-4117-957b-283371def679" xlink:href="hnst-20211231.xsd#hnst_SeriesDRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesDRedeemableConvertiblePreferredStockMember_9670feab-c060-4117-957b-283371def679" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesERedeemableConvertiblePreferredStockMember_53f2a6d7-b98c-433e-b212-b75ccb55c471" xlink:href="hnst-20211231.xsd#hnst_SeriesERedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesERedeemableConvertiblePreferredStockMember_53f2a6d7-b98c-433e-b212-b75ccb55c471" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SeriesFRedeemableConvertiblePreferredStockMember_a7871b68-bd66-44cd-a5db-d0fd6d8eb766" xlink:href="hnst-20211231.xsd#hnst_SeriesFRedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_a8a28d3e-50ca-4156-b9f1-b44cab33148b" xlink:to="loc_hnst_SeriesFRedeemableConvertiblePreferredStockMember_a7871b68-bd66-44cd-a5db-d0fd6d8eb766" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RedeemableConvertiblePreferredStockandStockholdersDeficitScheduleofStockAvailableforFutureIssuanceDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#RedeemableConvertiblePreferredStockandStockholdersDeficitScheduleofStockAvailableforFutureIssuanceDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RedeemableConvertiblePreferredStockandStockholdersDeficitScheduleofStockAvailableforFutureIssuanceDetails" xlink:type="extended" id="ife2dae8685534d7eb4c4cbd5efb4a968_RedeemableConvertiblePreferredStockandStockholdersDeficitScheduleofStockAvailableforFutureIssuanceDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_9ed688dd-02be-46f1-9b8d-8895498ff120" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_812d3767-3b57-4cc2-a111-b28f3574d657" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9ed688dd-02be-46f1-9b8d-8895498ff120" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_812d3767-3b57-4cc2-a111-b28f3574d657" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_55204183-c7d2-4bbe-8495-0646d19dbe64" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_9ed688dd-02be-46f1-9b8d-8895498ff120" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_55204183-c7d2-4bbe-8495-0646d19dbe64" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a601b9be-e749-4510-9292-fe9912737ee8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_55204183-c7d2-4bbe-8495-0646d19dbe64" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a601b9be-e749-4510-9292-fe9912737ee8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a601b9be-e749-4510-9292-fe9912737ee8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a601b9be-e749-4510-9292-fe9912737ee8" xlink:to="loc_us-gaap_ClassOfStockDomain_a601b9be-e749-4510-9292-fe9912737ee8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a601b9be-e749-4510-9292-fe9912737ee8" xlink:to="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_AuthorizedNumberOfCommonSharesMember_ab9e4e24-90c9-42e5-b32d-1507188633b8" xlink:href="hnst-20211231.xsd#hnst_AuthorizedNumberOfCommonSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:to="loc_hnst_AuthorizedNumberOfCommonSharesMember_ab9e4e24-90c9-42e5-b32d-1507188633b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_CommonSharesOutstandingMember_f8c35f8a-610b-4af4-8dfe-2411b7abf5eb" xlink:href="hnst-20211231.xsd#hnst_CommonSharesOutstandingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:to="loc_hnst_CommonSharesOutstandingMember_f8c35f8a-610b-4af4-8dfe-2411b7abf5eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_StockAwardsOutstandingUnderThe2011PlanMember_0335be03-4c99-41d9-8276-1c3fd72002ac" xlink:href="hnst-20211231.xsd#hnst_StockAwardsOutstandingUnderThe2011PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:to="loc_hnst_StockAwardsOutstandingUnderThe2011PlanMember_0335be03-4c99-41d9-8276-1c3fd72002ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_StockAwardsAvailableForGrantUnderThe2011PlanMember_9687329c-a6ec-4595-96b0-62b8dd5313c6" xlink:href="hnst-20211231.xsd#hnst_StockAwardsAvailableForGrantUnderThe2011PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:to="loc_hnst_StockAwardsAvailableForGrantUnderThe2011PlanMember_9687329c-a6ec-4595-96b0-62b8dd5313c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ReserveForTheConversionOfPreferredStockMember_fee6cd65-5e7c-43f9-a9f3-a585702319cf" xlink:href="hnst-20211231.xsd#hnst_ReserveForTheConversionOfPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_08198c4c-7692-436c-9fae-27946bf009bd" xlink:to="loc_hnst_ReserveForTheConversionOfPreferredStockMember_fee6cd65-5e7c-43f9-a9f3-a585702319cf" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/CommitmentsandContingenciesAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#CommitmentsandContingenciesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/CommitmentsandContingenciesAdditionalInformationDetails" xlink:type="extended" id="i07aaa0f1b91c485787ba8477b7502f11_CommitmentsandContingenciesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_f6d47d9a-0162-4edb-9616-cef70c594325" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_f6d47d9a-0162-4edb-9616-cef70c594325" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_8d29f46b-7c6b-41f4-a88c-a86efba90a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_8d29f46b-7c6b-41f4-a88c-a86efba90a5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementInterest_9a9aab8c-eda3-4623-ac9f-a9a0fe54e0cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationSettlementInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_LitigationSettlementInterest_9a9aab8c-eda3-4623-ac9f-a9a0fe54e0cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_OperatingLeaseNumberOfRenewalOptions_39b64ddd-4713-41f2-9cb5-0e382d3fac43" xlink:href="hnst-20211231.xsd#hnst_OperatingLeaseNumberOfRenewalOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_hnst_OperatingLeaseNumberOfRenewalOptions_39b64ddd-4713-41f2-9cb5-0e382d3fac43" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_695f4f38-6316-479f-a844-2bc000383e1b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_695f4f38-6316-479f-a844-2bc000383e1b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNet_c0dac6b9-afcb-483b-bf07-d9f67436ff7f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNet_c0dac6b9-afcb-483b-bf07-d9f67436ff7f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeaseObligationsNoncurrent_f213851f-9209-4f9f-98e4-41470b7578f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeaseObligationsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_CapitalLeaseObligationsNoncurrent_f213851f-9209-4f9f-98e4-41470b7578f4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_6a842751-8c6c-482f-8a29-a790e1188231" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_6a842751-8c6c-482f-8a29-a790e1188231" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_LesseeOperatingLeaseEscalationClauseUpdateTerm_7ed28e6e-e6f7-4f1f-935e-dc671cdcd546" xlink:href="hnst-20211231.xsd#hnst_LesseeOperatingLeaseEscalationClauseUpdateTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_hnst_LesseeOperatingLeaseEscalationClauseUpdateTerm_7ed28e6e-e6f7-4f1f-935e-dc671cdcd546" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesRentExpenseNet_4234c150-049f-4a57-8dd9-2ca6a57f98d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_OperatingLeasesRentExpenseNet_4234c150-049f-4a57-8dd9-2ca6a57f98d2" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue_8c69857e-1368-44fa-9516-9da261fd73b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_OperatingLeasesIncomeStatementSubleaseRevenue_8c69857e-1368-44fa-9516-9da261fd73b3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_a831f8cc-56e1-4ec8-95a8-3fed007a0c74" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_a831f8cc-56e1-4ec8-95a8-3fed007a0c74" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_OperatingLeasesSubleaseTermExtension_37fc8e27-cd79-4700-a432-06da205640b9" xlink:href="hnst-20211231.xsd#hnst_OperatingLeasesSubleaseTermExtension"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_hnst_OperatingLeasesSubleaseTermExtension_37fc8e27-cd79-4700-a432-06da205640b9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_a4e80068-810d-4882-87f1-7f0aa8afdf18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_7871a3a9-6b98-4959-ba0a-6a9f09fc3441" xlink:to="loc_us-gaap_LossContingenciesTable_a4e80068-810d-4882-87f1-7f0aa8afdf18" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_6d27bd88-cd4f-4252-b4d3-060959c21527" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_a4e80068-810d-4882-87f1-7f0aa8afdf18" xlink:to="loc_srt_LitigationCaseAxis_6d27bd88-cd4f-4252-b4d3-060959c21527" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_6d27bd88-cd4f-4252-b4d3-060959c21527_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_6d27bd88-cd4f-4252-b4d3-060959c21527" xlink:to="loc_srt_LitigationCaseTypeDomain_6d27bd88-cd4f-4252-b4d3-060959c21527_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_16a06488-9786-430f-9992-ef5cb160b881" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_6d27bd88-cd4f-4252-b4d3-060959c21527" xlink:to="loc_srt_LitigationCaseTypeDomain_16a06488-9786-430f-9992-ef5cb160b881" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_NevadaDepartmentOfTaxationVsTheHonestCompanyIncMember_5ac57fd1-d249-4b89-ba37-c2d824636e96" xlink:href="hnst-20211231.xsd#hnst_NevadaDepartmentOfTaxationVsTheHonestCompanyIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_16a06488-9786-430f-9992-ef5cb160b881" xlink:to="loc_hnst_NevadaDepartmentOfTaxationVsTheHonestCompanyIncMember_5ac57fd1-d249-4b89-ba37-c2d824636e96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_e3e78934-030b-4a0b-adce-a67b0529b2f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_a4e80068-810d-4882-87f1-7f0aa8afdf18" xlink:to="loc_us-gaap_LitigationStatusAxis_e3e78934-030b-4a0b-adce-a67b0529b2f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_e3e78934-030b-4a0b-adce-a67b0529b2f6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_e3e78934-030b-4a0b-adce-a67b0529b2f6" xlink:to="loc_us-gaap_LitigationStatusDomain_e3e78934-030b-4a0b-adce-a67b0529b2f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_f315d902-4d7a-4b6a-af7d-d14b2ba0debb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_e3e78934-030b-4a0b-adce-a67b0529b2f6" xlink:to="loc_us-gaap_LitigationStatusDomain_f315d902-4d7a-4b6a-af7d-d14b2ba0debb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_ff377c08-1443-49a4-87aa-76e3b2c90d87" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_f315d902-4d7a-4b6a-af7d-d14b2ba0debb" xlink:to="loc_us-gaap_PendingLitigationMember_ff377c08-1443-49a4-87aa-76e3b2c90d87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_cebb7795-7a40-43ef-8390-ab168ab3f929" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_a4e80068-810d-4882-87f1-7f0aa8afdf18" xlink:to="loc_us-gaap_OtherCommitmentsAxis_cebb7795-7a40-43ef-8390-ab168ab3f929" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_cebb7795-7a40-43ef-8390-ab168ab3f929_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_cebb7795-7a40-43ef-8390-ab168ab3f929" xlink:to="loc_us-gaap_OtherCommitmentsDomain_cebb7795-7a40-43ef-8390-ab168ab3f929_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_a852293a-7ddf-46c2-8412-9674bbb550cc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_cebb7795-7a40-43ef-8390-ab168ab3f929" xlink:to="loc_us-gaap_OtherCommitmentsDomain_a852293a-7ddf-46c2-8412-9674bbb550cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_WarehouseFacilityOperatingLeaseMember_b7821b8d-64fa-416a-a6b4-c4558e60df1c" xlink:href="hnst-20211231.xsd#hnst_WarehouseFacilityOperatingLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_a852293a-7ddf-46c2-8412-9674bbb550cc" xlink:to="loc_hnst_WarehouseFacilityOperatingLeaseMember_b7821b8d-64fa-416a-a6b4-c4558e60df1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_OfficeFacilityLeaseMember_606aaaa5-f1a6-43bd-ae83-385920821ede" xlink:href="hnst-20211231.xsd#hnst_OfficeFacilityLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_a852293a-7ddf-46c2-8412-9674bbb550cc" xlink:to="loc_hnst_OfficeFacilityLeaseMember_606aaaa5-f1a6-43bd-ae83-385920821ede" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/CommitmentsandContingenciesSummaryofMinimumFutureRentObligationsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#CommitmentsandContingenciesSummaryofMinimumFutureRentObligationsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/CommitmentsandContingenciesSummaryofMinimumFutureRentObligationsDetails" xlink:type="extended" id="icc3c11ca08854b638d99193ff4933216_CommitmentsandContingenciesSummaryofMinimumFutureRentObligationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_4e5dc386-e438-4cfd-b424-5b07653ec3d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_4e5dc386-e438-4cfd-b424-5b07653ec3d7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_5eeec68d-d900-412d-95c4-271140fa11be" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_5eeec68d-d900-412d-95c4-271140fa11be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_d1856b3d-f512-4ae3-9912-4cbcebb2d97d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_d1856b3d-f512-4ae3-9912-4cbcebb2d97d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_8e0d32f2-13c4-4305-bed0-18bc73f0e9cc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_8e0d32f2-13c4-4305-bed0-18bc73f0e9cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_f18fc3ab-c5ed-47ed-a9a1-3616e353dee2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_f18fc3ab-c5ed-47ed-a9a1-3616e353dee2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_8dff3716-d342-47b7-87cb-8553ed69ee5c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_8dff3716-d342-47b7-87cb-8553ed69ee5c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_974d261e-3631-4224-815c-7d391d5efa62" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_974d261e-3631-4224-815c-7d391d5efa62" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_1e36e982-7c51-47ba-9395-e62530a66b80" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_2bbe7f99-1ff1-434f-b7cf-92edb5336ca7" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_1e36e982-7c51-47ba-9395-e62530a66b80" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:href="hnst-20211231.xsd#hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_4e5dc386-e438-4cfd-b424-5b07653ec3d7" xlink:to="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_91f96513-36fb-4830-ab8b-b042b7882c7a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_91f96513-36fb-4830-ab8b-b042b7882c7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_b5b58bdb-2179-4eff-85ec-882d867abb39" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_b5b58bdb-2179-4eff-85ec-882d867abb39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_dbf137ef-23e3-4407-8385-5e4524054fec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_dbf137ef-23e3-4407-8385-5e4524054fec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_e72f2ca8-9881-40ca-af2c-bfd8f594a151" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_e72f2ca8-9881-40ca-af2c-bfd8f594a151" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_402c95b0-3b97-4188-a745-5b983f2790b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_402c95b0-3b97-4188-a745-5b983f2790b4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_edb2760a-3999-4b5c-b349-d28dda193212" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_edb2760a-3999-4b5c-b349-d28dda193212" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_58fc3858-bb89-43a5-aad1-0ddfce8ca5fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hnst_OperatingLeasesFutureMinimumPaymentsSubleaseDueFiscalYearMaturityAbstract_5b849529-1ac6-4178-b0b6-34a319dee7e0" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_58fc3858-bb89-43a5-aad1-0ddfce8ca5fd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_4e5dc386-e438-4cfd-b424-5b07653ec3d7" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent_a7dcd807-1556-472d-82c9-e8e68cc83162" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent_a7dcd807-1556-472d-82c9-e8e68cc83162" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears_de8efef9-e3ad-48e3-8789-8f73c1e91823" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears_de8efef9-e3ad-48e3-8789-8f73c1e91823" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears_57676a94-b5da-4a82-992b-a5487812af59" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears_57676a94-b5da-4a82-992b-a5487812af59" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears_50dbf087-18ee-45f5-b37c-6340189a55a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears_50dbf087-18ee-45f5-b37c-6340189a55a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears_e5995b31-8dfc-41b3-8b6f-8b35005b10f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears_e5995b31-8dfc-41b3-8b6f-8b35005b10f4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter_899b7d3e-aad3-4647-ae49-e75bbe698ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter_899b7d3e-aad3-4647-ae49-e75bbe698ce8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_25015f0f-711f-417e-a17c-1564bbb51af0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_25015f0f-711f-417e-a17c-1564bbb51af0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments_adf00de3-e30a-46db-a299-5422d92a5431" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsInterestIncludedInPayments_adf00de3-e30a-46db-a299-5422d92a5431" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments_6f90dfcb-2064-4359-8859-25054f512e69" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueAbstract_26a49612-add9-4668-96e4-a5a0499294ef" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsPresentValueOfNetMinimumPayments_6f90dfcb-2064-4359-8859-25054f512e69" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_1e677f17-2032-48ee-924b-47e97b3e68e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_4e5dc386-e438-4cfd-b424-5b07653ec3d7" xlink:to="loc_us-gaap_OtherCommitmentsTable_1e677f17-2032-48ee-924b-47e97b3e68e1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsAxis_f8336235-3101-46e7-bd4e-057e3476f65f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_1e677f17-2032-48ee-924b-47e97b3e68e1" xlink:to="loc_us-gaap_OtherCommitmentsAxis_f8336235-3101-46e7-bd4e-057e3476f65f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_f8336235-3101-46e7-bd4e-057e3476f65f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherCommitmentsAxis_f8336235-3101-46e7-bd4e-057e3476f65f" xlink:to="loc_us-gaap_OtherCommitmentsDomain_f8336235-3101-46e7-bd4e-057e3476f65f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsDomain_6cb925fe-5d78-4832-86cd-3a675a906263" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherCommitmentsAxis_f8336235-3101-46e7-bd4e-057e3476f65f" xlink:to="loc_us-gaap_OtherCommitmentsDomain_6cb925fe-5d78-4832-86cd-3a675a906263" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_FacilityLeasesMember_4b087437-3d1e-4fa5-a778-7d56d3770b82" xlink:href="hnst-20211231.xsd#hnst_FacilityLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_6cb925fe-5d78-4832-86cd-3a675a906263" xlink:to="loc_hnst_FacilityLeasesMember_4b087437-3d1e-4fa5-a778-7d56d3770b82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_WarehouseFacilityOperatingLeaseMember_61ad0c87-880c-457b-b568-f7035b9e9a17" xlink:href="hnst-20211231.xsd#hnst_WarehouseFacilityOperatingLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsDomain_6cb925fe-5d78-4832-86cd-3a675a906263" xlink:to="loc_hnst_WarehouseFacilityOperatingLeaseMember_61ad0c87-880c-457b-b568-f7035b9e9a17" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationStockOptionActivityNarrativeDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensationStockOptionActivityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationStockOptionActivityNarrativeDetails" xlink:type="extended" id="ifc69d5f26db04f598de90422456a3761_StockBasedCompensationStockOptionActivityNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_3a58b176-f04d-4c56-a537-af37d78ca218" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_3a58b176-f04d-4c56-a537-af37d78ca218" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_55c667b8-d443-4ea7-b6dc-1ee82f90e378" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_55c667b8-d443-4ea7-b6dc-1ee82f90e378" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_b46c8c68-b256-4760-9497-812c5fcb165f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_b46c8c68-b256-4760-9497-812c5fcb165f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_5de64c22-f75c-4173-ad91-1093fa5b1f50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_5de64c22-f75c-4173-ad91-1093fa5b1f50" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_742c752f-32c0-4c0d-9599-daaa708b1722" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_742c752f-32c0-4c0d-9599-daaa708b1722" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_708e0002-f706-4e47-8614-a8a4f2d19db0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_708e0002-f706-4e47-8614-a8a4f2d19db0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_1f40194c-1278-4c33-8bf0-228391a5970a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_1f40194c-1278-4c33-8bf0-228391a5970a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_6f915b1d-04d7-4d29-8c4c-e256b43cf1e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_6f915b1d-04d7-4d29-8c4c-e256b43cf1e6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_0a29704f-e5f0-4d51-98f6-47e9139fdecd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_0a29704f-e5f0-4d51-98f6-47e9139fdecd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_37c1d9d1-f726-4895-9ec0-3728c291646c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_559bc34d-8b00-4574-9fa2-a7f4957919dc" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_37c1d9d1-f726-4895-9ec0-3728c291646c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_481e3b35-d760-429f-9ae3-4b0725575e50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_37c1d9d1-f726-4895-9ec0-3728c291646c" xlink:to="loc_us-gaap_AwardTypeAxis_481e3b35-d760-429f-9ae3-4b0725575e50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_481e3b35-d760-429f-9ae3-4b0725575e50_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_481e3b35-d760-429f-9ae3-4b0725575e50" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_481e3b35-d760-429f-9ae3-4b0725575e50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44fdc519-909a-4f15-9f4d-4d1d59dd329a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_481e3b35-d760-429f-9ae3-4b0725575e50" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44fdc519-909a-4f15-9f4d-4d1d59dd329a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_StockOptionsWithLiquidityEventVestingConditionsMember_b6770581-e56f-4aae-b234-92bcdb26ffe2" xlink:href="hnst-20211231.xsd#hnst_StockOptionsWithLiquidityEventVestingConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44fdc519-909a-4f15-9f4d-4d1d59dd329a" xlink:to="loc_hnst_StockOptionsWithLiquidityEventVestingConditionsMember_b6770581-e56f-4aae-b234-92bcdb26ffe2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_dcf15e79-2855-4ca2-9b48-ec271808e85f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_44fdc519-909a-4f15-9f4d-4d1d59dd329a" xlink:to="loc_us-gaap_EmployeeStockOptionMember_dcf15e79-2855-4ca2-9b48-ec271808e85f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_c79ff6ef-e600-4299-941e-d63498b566b6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_37c1d9d1-f726-4895-9ec0-3728c291646c" xlink:to="loc_us-gaap_PlanNameAxis_c79ff6ef-e600-4299-941e-d63498b566b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_c79ff6ef-e600-4299-941e-d63498b566b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_c79ff6ef-e600-4299-941e-d63498b566b6" xlink:to="loc_us-gaap_PlanNameDomain_c79ff6ef-e600-4299-941e-d63498b566b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_de432e8e-f196-468d-9f92-c617fb5b630a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_c79ff6ef-e600-4299-941e-d63498b566b6" xlink:to="loc_us-gaap_PlanNameDomain_de432e8e-f196-468d-9f92-c617fb5b630a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2011StockIncentivePlanMember_eed9d7ab-98e3-4a6a-8d29-ed9cbe8d663a" xlink:href="hnst-20211231.xsd#hnst_A2011StockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_de432e8e-f196-468d-9f92-c617fb5b630a" xlink:to="loc_hnst_A2011StockIncentivePlanMember_eed9d7ab-98e3-4a6a-8d29-ed9cbe8d663a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensation2021EquityIncentivePlanDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensation2021EquityIncentivePlanDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensation2021EquityIncentivePlanDetails" xlink:type="extended" id="i09eafad4091e442095c53d7673bb143c_StockBasedCompensation2021EquityIncentivePlanDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9a3d6872-db6b-4051-9d46-ba73e89b15b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_f4271470-bb70-4935-a145-dc2e79655459" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9a3d6872-db6b-4051-9d46-ba73e89b15b3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_f4271470-bb70-4935-a145-dc2e79655459" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod_dc659e46-b67f-4c46-9300-d99d81373a66" xlink:href="hnst-20211231.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9a3d6872-db6b-4051-9d46-ba73e89b15b3" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod_dc659e46-b67f-4c46-9300-d99d81373a66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_15bdf133-5297-4996-96f2-b2f4d2abb607" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9a3d6872-db6b-4051-9d46-ba73e89b15b3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_15bdf133-5297-4996-96f2-b2f4d2abb607" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1b25bb45-30f5-4247-89df-267bf3e604f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9a3d6872-db6b-4051-9d46-ba73e89b15b3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1b25bb45-30f5-4247-89df-267bf3e604f0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_34024ca3-f913-43ea-bdff-9aa9529836d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1b25bb45-30f5-4247-89df-267bf3e604f0" xlink:to="loc_us-gaap_PlanNameAxis_34024ca3-f913-43ea-bdff-9aa9529836d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_34024ca3-f913-43ea-bdff-9aa9529836d3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_34024ca3-f913-43ea-bdff-9aa9529836d3" xlink:to="loc_us-gaap_PlanNameDomain_34024ca3-f913-43ea-bdff-9aa9529836d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_a6afa6ca-6fb4-4d2d-95b6-5a0bb30a1219" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_34024ca3-f913-43ea-bdff-9aa9529836d3" xlink:to="loc_us-gaap_PlanNameDomain_a6afa6ca-6fb4-4d2d-95b6-5a0bb30a1219" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021EquityIncentivePlanMember_f4f42797-dd2f-4193-80d1-2daaa09f0d35" xlink:href="hnst-20211231.xsd#hnst_A2021EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_a6afa6ca-6fb4-4d2d-95b6-5a0bb30a1219" xlink:to="loc_hnst_A2021EquityIncentivePlanMember_f4f42797-dd2f-4193-80d1-2daaa09f0d35" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationRSUAwardsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensationRSUAwardsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationRSUAwardsDetails" xlink:type="extended" id="i12b95890f5504a438b1f40c348800590_StockBasedCompensationRSUAwardsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_851819a0-2c45-4e9b-aa24-9b4f01a4f777" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_20201cd9-f248-4517-96bd-1ce97bf3dd9d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_851819a0-2c45-4e9b-aa24-9b4f01a4f777" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_20201cd9-f248-4517-96bd-1ce97bf3dd9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_8e27d3b5-e790-42fb-acad-5937260e1f23" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_20201cd9-f248-4517-96bd-1ce97bf3dd9d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_8e27d3b5-e790-42fb-acad-5937260e1f23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_4c2ab88e-2678-4463-b7f4-3373ac36fa9e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_20201cd9-f248-4517-96bd-1ce97bf3dd9d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_4c2ab88e-2678-4463-b7f4-3373ac36fa9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_deaca6fe-0491-4bd0-a804-2863d5a198cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_20201cd9-f248-4517-96bd-1ce97bf3dd9d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_deaca6fe-0491-4bd0-a804-2863d5a198cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c270edc1-4bfb-4065-a7c2-9d2849e4c6e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_20201cd9-f248-4517-96bd-1ce97bf3dd9d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c270edc1-4bfb-4065-a7c2-9d2849e4c6e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6489933e-52c2-4fb2-aa64-cff635394eb4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b281e71a-dd0f-4f56-9992-6a4db53c663a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_851819a0-2c45-4e9b-aa24-9b4f01a4f777" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b281e71a-dd0f-4f56-9992-6a4db53c663a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_c8a1df52-13cd-4421-9574-9d4601429aaf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b281e71a-dd0f-4f56-9992-6a4db53c663a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_c8a1df52-13cd-4421-9574-9d4601429aaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_32be48a2-acc9-4386-8650-1cb27e4913fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b281e71a-dd0f-4f56-9992-6a4db53c663a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_32be48a2-acc9-4386-8650-1cb27e4913fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_68fc4bcc-a387-48e3-8fa1-c60df9cfb11d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b281e71a-dd0f-4f56-9992-6a4db53c663a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_68fc4bcc-a387-48e3-8fa1-c60df9cfb11d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_7211bf52-7cde-4e62-a6bc-e310320ce2f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_b281e71a-dd0f-4f56-9992-6a4db53c663a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_7211bf52-7cde-4e62-a6bc-e310320ce2f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_d1379187-896c-49eb-aee3-646c9d0e48de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_5e4b35df-84c9-46f4-b60d-c6a27e144be3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_851819a0-2c45-4e9b-aa24-9b4f01a4f777" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_5e4b35df-84c9-46f4-b60d-c6a27e144be3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9ba2cb5b-5eca-443c-9169-094ff706b1d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_851819a0-2c45-4e9b-aa24-9b4f01a4f777" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9ba2cb5b-5eca-443c-9169-094ff706b1d7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_71ccaa3b-fb6d-4f1a-92f7-292f6a507e84" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9ba2cb5b-5eca-443c-9169-094ff706b1d7" xlink:to="loc_us-gaap_AwardTypeAxis_71ccaa3b-fb6d-4f1a-92f7-292f6a507e84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_71ccaa3b-fb6d-4f1a-92f7-292f6a507e84_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_71ccaa3b-fb6d-4f1a-92f7-292f6a507e84" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_71ccaa3b-fb6d-4f1a-92f7-292f6a507e84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fb153a80-59a3-4bf6-b938-aa96b93c91ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_71ccaa3b-fb6d-4f1a-92f7-292f6a507e84" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fb153a80-59a3-4bf6-b938-aa96b93c91ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_c1d771bd-e64e-409e-8cc5-e92e70f90308" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fb153a80-59a3-4bf6-b938-aa96b93c91ef" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_c1d771bd-e64e-409e-8cc5-e92e70f90308" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_46ea80c4-4c87-4441-90dc-4ae33c844499" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9ba2cb5b-5eca-443c-9169-094ff706b1d7" xlink:to="loc_us-gaap_PlanNameAxis_46ea80c4-4c87-4441-90dc-4ae33c844499" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_46ea80c4-4c87-4441-90dc-4ae33c844499_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_46ea80c4-4c87-4441-90dc-4ae33c844499" xlink:to="loc_us-gaap_PlanNameDomain_46ea80c4-4c87-4441-90dc-4ae33c844499_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_7ff3430c-7ed3-480d-a0ec-8e1718678f80" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_46ea80c4-4c87-4441-90dc-4ae33c844499" xlink:to="loc_us-gaap_PlanNameDomain_7ff3430c-7ed3-480d-a0ec-8e1718678f80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2011StockIncentivePlanMember_41626469-f5df-4323-ae31-4d7d5ae13132" xlink:href="hnst-20211231.xsd#hnst_A2011StockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_7ff3430c-7ed3-480d-a0ec-8e1718678f80" xlink:to="loc_hnst_A2011StockIncentivePlanMember_41626469-f5df-4323-ae31-4d7d5ae13132" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021EquityIncentivePlanMember_6a831224-5a72-438f-ada2-43de4476db02" xlink:href="hnst-20211231.xsd#hnst_A2021EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_7ff3430c-7ed3-480d-a0ec-8e1718678f80" xlink:to="loc_hnst_A2021EquityIncentivePlanMember_6a831224-5a72-438f-ada2-43de4476db02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_b9f85929-eb77-42ed-87be-4368546b6811" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9ba2cb5b-5eca-443c-9169-094ff706b1d7" xlink:to="loc_us-gaap_GranteeStatusAxis_b9f85929-eb77-42ed-87be-4368546b6811" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_b9f85929-eb77-42ed-87be-4368546b6811_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_b9f85929-eb77-42ed-87be-4368546b6811" xlink:to="loc_us-gaap_GranteeStatusDomain_b9f85929-eb77-42ed-87be-4368546b6811_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_0060cedb-b3eb-4642-99ef-5f66fbcb1c16" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_b9f85929-eb77-42ed-87be-4368546b6811" xlink:to="loc_us-gaap_GranteeStatusDomain_0060cedb-b3eb-4642-99ef-5f66fbcb1c16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_NonEmployeeDirectorsMember_24f407bc-c51c-412b-8d26-f13661699320" xlink:href="hnst-20211231.xsd#hnst_NonEmployeeDirectorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_0060cedb-b3eb-4642-99ef-5f66fbcb1c16" xlink:to="loc_hnst_NonEmployeeDirectorsMember_24f407bc-c51c-412b-8d26-f13661699320" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DirectorsOfficersAndEmployeesMember_0242ce66-cf38-448f-8a60-e13c243e0abc" xlink:href="hnst-20211231.xsd#hnst_DirectorsOfficersAndEmployeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_0060cedb-b3eb-4642-99ef-5f66fbcb1c16" xlink:to="loc_hnst_DirectorsOfficersAndEmployeesMember_0242ce66-cf38-448f-8a60-e13c243e0abc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_1eb11771-1fa5-45b5-af22-3af6f62c44bb" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9ba2cb5b-5eca-443c-9169-094ff706b1d7" xlink:to="loc_srt_TitleOfIndividualAxis_1eb11771-1fa5-45b5-af22-3af6f62c44bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1eb11771-1fa5-45b5-af22-3af6f62c44bb_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_1eb11771-1fa5-45b5-af22-3af6f62c44bb" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1eb11771-1fa5-45b5-af22-3af6f62c44bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_8c6bb31f-db49-4519-99d1-282eae09027d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_1eb11771-1fa5-45b5-af22-3af6f62c44bb" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_8c6bb31f-db49-4519-99d1-282eae09027d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficerMember_fa69ea27-e93d-4663-b591-70d78baa19c4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_8c6bb31f-db49-4519-99d1-282eae09027d" xlink:to="loc_srt_OfficerMember_fa69ea27-e93d-4663-b591-70d78baa19c4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationRSUAwardsNarrativeDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensationRSUAwardsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationRSUAwardsNarrativeDetails" xlink:type="extended" id="ie4fde9fce9d1409db997d863c9299498_StockBasedCompensationRSUAwardsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2339f45-a4b0-4082-8a01-56ae618cb350" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_bff16383-e866-4c1b-a9fc-dfac48d94403" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2339f45-a4b0-4082-8a01-56ae618cb350" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_bff16383-e866-4c1b-a9fc-dfac48d94403" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6a3ef666-c9c8-4d6c-aca4-f797b17c6d05" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2339f45-a4b0-4082-8a01-56ae618cb350" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6a3ef666-c9c8-4d6c-aca4-f797b17c6d05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c843348b-b8da-4338-bfdb-1b69e6c0a9c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a2339f45-a4b0-4082-8a01-56ae618cb350" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c843348b-b8da-4338-bfdb-1b69e6c0a9c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_f71de188-120c-467c-9480-084de21c6744" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c843348b-b8da-4338-bfdb-1b69e6c0a9c2" xlink:to="loc_us-gaap_AwardTypeAxis_f71de188-120c-467c-9480-084de21c6744" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f71de188-120c-467c-9480-084de21c6744_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_f71de188-120c-467c-9480-084de21c6744" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f71de188-120c-467c-9480-084de21c6744_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_427bc574-8f3d-4448-b207-f3cd00fb393c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_f71de188-120c-467c-9480-084de21c6744" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_427bc574-8f3d-4448-b207-f3cd00fb393c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_8da3eed8-fe18-4ce2-bdde-a198d5d39877" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_427bc574-8f3d-4448-b207-f3cd00fb393c" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_8da3eed8-fe18-4ce2-bdde-a198d5d39877" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensation2021EmployeeStockPurchasePlanDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensation2021EmployeeStockPurchasePlanDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensation2021EmployeeStockPurchasePlanDetails" xlink:type="extended" id="i88c517599a144e5ea46eec819c0deab5_StockBasedCompensation2021EmployeeStockPurchasePlanDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_de96b262-a0d5-489a-ad22-88cf376c6f3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_de96b262-a0d5-489a-ad22-88cf376c6f3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod_fb1697b8-a7b3-4375-8ea1-d5b610c321a5" xlink:href="hnst-20211231.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod_fb1697b8-a7b3-4375-8ea1-d5b610c321a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_bc446c3d-d1a4-46dc-8b39-9c0e685b25cc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_bc446c3d-d1a4-46dc-8b39-9c0e685b25cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_6afc79cb-6254-462d-9afc-2d501f84c99a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_6afc79cb-6254-462d-9afc-2d501f84c99a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_b6fcccdc-19ba-4704-8601-9bde69b32cc8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_b6fcccdc-19ba-4704-8601-9bde69b32cc8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_ed660733-0630-4bb2-9f39-d6ce4892ec07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_ed660733-0630-4bb2-9f39-d6ce4892ec07" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_9201e44d-32c6-445f-ba4f-6b3c0e3a8696" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_9201e44d-32c6-445f-ba4f-6b3c0e3a8696" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_ce8aeca4-0f09-4d39-b831-38187e902184" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_SharePrice_ce8aeca4-0f09-4d39-b831-38187e902184" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_84ebd7bb-d970-4f6e-a946-38901d0ca312" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_84ebd7bb-d970-4f6e-a946-38901d0ca312" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a41c1125-be1c-48c5-a809-9adf41b8e457" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_46048e1a-1b1a-4348-a851-ddf001ec0977" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a41c1125-be1c-48c5-a809-9adf41b8e457" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_11ebb175-be35-4492-9b22-a8b2b74a4ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a41c1125-be1c-48c5-a809-9adf41b8e457" xlink:to="loc_us-gaap_AwardTypeAxis_11ebb175-be35-4492-9b22-a8b2b74a4ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_11ebb175-be35-4492-9b22-a8b2b74a4ebf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_11ebb175-be35-4492-9b22-a8b2b74a4ebf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_11ebb175-be35-4492-9b22-a8b2b74a4ebf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_be016d2c-6b5b-4a98-9239-49f4b38d9a13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_11ebb175-be35-4492-9b22-a8b2b74a4ebf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_be016d2c-6b5b-4a98-9239-49f4b38d9a13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_07b67be6-a027-401f-b944-93289651fcbb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_be016d2c-6b5b-4a98-9239-49f4b38d9a13" xlink:to="loc_us-gaap_EmployeeStockMember_07b67be6-a027-401f-b944-93289651fcbb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_89a81b65-b746-4e3d-b2db-af6da78d1ac5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_a41c1125-be1c-48c5-a809-9adf41b8e457" xlink:to="loc_us-gaap_PlanNameAxis_89a81b65-b746-4e3d-b2db-af6da78d1ac5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_89a81b65-b746-4e3d-b2db-af6da78d1ac5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_89a81b65-b746-4e3d-b2db-af6da78d1ac5" xlink:to="loc_us-gaap_PlanNameDomain_89a81b65-b746-4e3d-b2db-af6da78d1ac5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_87485d55-0b9a-4f85-8715-ad202a4d25dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_89a81b65-b746-4e3d-b2db-af6da78d1ac5" xlink:to="loc_us-gaap_PlanNameDomain_87485d55-0b9a-4f85-8715-ad202a4d25dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021EmployeeStockPurchasePlanMember_8740e4d0-5507-4ce5-b5e6-af65dccfa934" xlink:href="hnst-20211231.xsd#hnst_A2021EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_87485d55-0b9a-4f85-8715-ad202a4d25dc" xlink:to="loc_hnst_A2021EmployeeStockPurchasePlanMember_8740e4d0-5507-4ce5-b5e6-af65dccfa934" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails" xlink:type="extended" id="ib37ba8297902460687c38b12da384743_StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_8e248e81-cd6b-4ff4-8607-3b632d025d15" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_8e248e81-cd6b-4ff4-8607-3b632d025d15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_35d68d1e-7d13-41e2-b931-9e3c61412901" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_35d68d1e-7d13-41e2-b931-9e3c61412901" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_96bfd572-6758-491f-9d11-9634b511fdca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_96bfd572-6758-491f-9d11-9634b511fdca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_63f446cc-009c-492c-bc48-5f50a2551f34" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_63f446cc-009c-492c-bc48-5f50a2551f34" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_fa93034d-3eae-4099-8dcb-a088d1c62c61" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_fa93034d-3eae-4099-8dcb-a088d1c62c61" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_0a7b0bea-3896-428c-b128-4ef40f759993" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_0a7b0bea-3896-428c-b128-4ef40f759993" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_5e0df9ff-2441-4382-9c04-e448915ac9ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_5e0df9ff-2441-4382-9c04-e448915ac9ae" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c5e2c684-c175-42e8-a204-32fc39f4d403" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2ee2b87f-7d7b-4f1b-81bd-5f80675912c3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c5e2c684-c175-42e8-a204-32fc39f4d403" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_8de6f847-e765-4ff7-9d7b-d6ab82f01719" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c5e2c684-c175-42e8-a204-32fc39f4d403" xlink:to="loc_us-gaap_AwardTypeAxis_8de6f847-e765-4ff7-9d7b-d6ab82f01719" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8de6f847-e765-4ff7-9d7b-d6ab82f01719_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8de6f847-e765-4ff7-9d7b-d6ab82f01719" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8de6f847-e765-4ff7-9d7b-d6ab82f01719_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_593ce7d3-e8be-4997-bf60-9977a189a951" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8de6f847-e765-4ff7-9d7b-d6ab82f01719" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_593ce7d3-e8be-4997-bf60-9977a189a951" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_7de87636-28c6-45ca-952e-c471fdc9a4e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_593ce7d3-e8be-4997-bf60-9977a189a951" xlink:to="loc_us-gaap_EmployeeStockOptionMember_7de87636-28c6-45ca-952e-c471fdc9a4e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_babbd2f4-e0b4-48f5-936a-eb448cb37046" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c5e2c684-c175-42e8-a204-32fc39f4d403" xlink:to="loc_srt_RangeAxis_babbd2f4-e0b4-48f5-936a-eb448cb37046" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_babbd2f4-e0b4-48f5-936a-eb448cb37046_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_babbd2f4-e0b4-48f5-936a-eb448cb37046" xlink:to="loc_srt_RangeMember_babbd2f4-e0b4-48f5-936a-eb448cb37046_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a8413aa1-7e75-4a7c-ae95-ea8e1efac30b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_babbd2f4-e0b4-48f5-936a-eb448cb37046" xlink:to="loc_srt_RangeMember_a8413aa1-7e75-4a7c-ae95-ea8e1efac30b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_e2271256-4306-4952-8a84-b9f1f5c1b278" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a8413aa1-7e75-4a7c-ae95-ea8e1efac30b" xlink:to="loc_srt_MinimumMember_e2271256-4306-4952-8a84-b9f1f5c1b278" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b605dc0f-3d2f-44b4-8cdb-3d01011fde38" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a8413aa1-7e75-4a7c-ae95-ea8e1efac30b" xlink:to="loc_srt_MaximumMember_b605dc0f-3d2f-44b4-8cdb-3d01011fde38" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#StockBasedCompensationStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationStockbasedCompensationExpenseDetails" xlink:type="extended" id="ibd14568a7025491db6ac1497bab481cb_StockBasedCompensationStockbasedCompensationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_a2119a9b-87d3-401b-a682-0c0615b25625" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_bfee43f5-5f6d-4dfe-b3d9-d323799ee36d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_a2119a9b-87d3-401b-a682-0c0615b25625" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_bfee43f5-5f6d-4dfe-b3d9-d323799ee36d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7b7ff564-89dc-48c6-92b0-f9e7bd062587" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_a2119a9b-87d3-401b-a682-0c0615b25625" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7b7ff564-89dc-48c6-92b0-f9e7bd062587" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_cafd18a5-714b-4b4a-9307-f7eb61a729f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_7b7ff564-89dc-48c6-92b0-f9e7bd062587" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_cafd18a5-714b-4b4a-9307-f7eb61a729f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_cafd18a5-714b-4b4a-9307-f7eb61a729f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_cafd18a5-714b-4b4a-9307-f7eb61a729f1" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_cafd18a5-714b-4b4a-9307-f7eb61a729f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_e7a98ce7-44f0-45f2-9c71-7612674e923b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_cafd18a5-714b-4b4a-9307-f7eb61a729f1" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_e7a98ce7-44f0-45f2-9c71-7612674e923b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_1dc1ac1f-4af3-4853-99b5-a56b2769bacf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e7a98ce7-44f0-45f2-9c71-7612674e923b" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_1dc1ac1f-4af3-4853-99b5-a56b2769bacf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_51253421-5b76-4b6a-b844-292c3e34cb5f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e7a98ce7-44f0-45f2-9c71-7612674e923b" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_51253421-5b76-4b6a-b844-292c3e34cb5f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails" xlink:type="extended" id="i44fa0ad9ace34cf4bcb45fff40c79eba_NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d3a51ee4-d487-4a77-9521-8fbfdfe5a792" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_302e936f-9282-4a21-bece-8942be45e0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d3a51ee4-d487-4a77-9521-8fbfdfe5a792" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_302e936f-9282-4a21-bece-8942be45e0bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_735ff3f7-c6ed-4cdb-b231-9983004ce9e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d3a51ee4-d487-4a77-9521-8fbfdfe5a792" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_735ff3f7-c6ed-4cdb-b231-9983004ce9e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_4863e96e-94f9-472f-9fa3-b7047e8c166f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d3a51ee4-d487-4a77-9521-8fbfdfe5a792" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_4863e96e-94f9-472f-9fa3-b7047e8c166f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_8ff1144d-ff4c-4b33-abdb-4a7765bc0d45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d3a51ee4-d487-4a77-9521-8fbfdfe5a792" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_8ff1144d-ff4c-4b33-abdb-4a7765bc0d45" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1ac2eee3-2fcc-404e-9eaf-6685e39c0c80" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d3a51ee4-d487-4a77-9521-8fbfdfe5a792" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1ac2eee3-2fcc-404e-9eaf-6685e39c0c80" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b9580274-7671-430a-a88e-43547baaa871" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1ac2eee3-2fcc-404e-9eaf-6685e39c0c80" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b9580274-7671-430a-a88e-43547baaa871" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b9580274-7671-430a-a88e-43547baaa871_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b9580274-7671-430a-a88e-43547baaa871" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b9580274-7671-430a-a88e-43547baaa871_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b7c8df10-8d3f-4f21-a884-5c2bf5c70e28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b9580274-7671-430a-a88e-43547baaa871" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b7c8df10-8d3f-4f21-a884-5c2bf5c70e28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_b9705104-5040-44d9-8b3d-ab42c108f94c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RedeemableConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b7c8df10-8d3f-4f21-a884-5c2bf5c70e28" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_b9705104-5040-44d9-8b3d-ab42c108f94c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_ae385ede-b57b-4db9-9d70-7752abf16a6a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b7c8df10-8d3f-4f21-a884-5c2bf5c70e28" xlink:to="loc_us-gaap_EmployeeStockOptionMember_ae385ede-b57b-4db9-9d70-7752abf16a6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_68c7a162-00e1-4b09-9926-9b6eba7feacb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b7c8df10-8d3f-4f21-a884-5c2bf5c70e28" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_68c7a162-00e1-4b09-9926-9b6eba7feacb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_bc9db379-130b-4bd8-b4b0-3228d0cad4ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b7c8df10-8d3f-4f21-a884-5c2bf5c70e28" xlink:to="loc_us-gaap_EmployeeStockMember_bc9db379-130b-4bd8-b4b0-3228d0cad4ae" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#IncomeTaxesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="extended" id="i74a062f1addb4359948c95d43a72f0c8_IncomeTaxesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_fa102f2f-8519-43a9-abf0-fae1a6e7636c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_3f95f5b3-39c7-414e-bc2f-3be0f8b8f9d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_fa102f2f-8519-43a9-abf0-fae1a6e7636c" xlink:to="loc_us-gaap_OperatingLossCarryforwards_3f95f5b3-39c7-414e-bc2f-3be0f8b8f9d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_400246c2-71a2-498e-b433-63ee81333659" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_fa102f2f-8519-43a9-abf0-fae1a6e7636c" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_400246c2-71a2-498e-b433-63ee81333659" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_c2876900-fd71-4be5-8a16-4b75534a4375" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_fa102f2f-8519-43a9-abf0-fae1a6e7636c" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_c2876900-fd71-4be5-8a16-4b75534a4375" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense_2f698649-8966-4068-916d-cf9a75da4aa5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_fa102f2f-8519-43a9-abf0-fae1a6e7636c" xlink:to="loc_us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense_2f698649-8966-4068-916d-cf9a75da4aa5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_16df2a5d-fea7-423a-b714-9e758699e522" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_fa102f2f-8519-43a9-abf0-fae1a6e7636c" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_16df2a5d-fea7-423a-b714-9e758699e522" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_43fdf0d0-5d99-402c-ad17-b144fa73903c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_16df2a5d-fea7-423a-b714-9e758699e522" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_43fdf0d0-5d99-402c-ad17-b144fa73903c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_43fdf0d0-5d99-402c-ad17-b144fa73903c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_43fdf0d0-5d99-402c-ad17-b144fa73903c" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_43fdf0d0-5d99-402c-ad17-b144fa73903c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_5dd635b3-9139-4a68-b03b-f3f844f768a1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_43fdf0d0-5d99-402c-ad17-b144fa73903c" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_5dd635b3-9139-4a68-b03b-f3f844f768a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_914f6edc-b048-446a-975a-7e64d45b7e4b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5dd635b3-9139-4a68-b03b-f3f844f768a1" xlink:to="loc_us-gaap_DomesticCountryMember_914f6edc-b048-446a-975a-7e64d45b7e4b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_02ee6fde-e9e8-4fd6-b07d-52219bba1979" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5dd635b3-9139-4a68-b03b-f3f844f768a1" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_02ee6fde-e9e8-4fd6-b07d-52219bba1979" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/IncomeTaxesSummaryofChangesinValuationAllowanceDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#IncomeTaxesSummaryofChangesinValuationAllowanceDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/IncomeTaxesSummaryofChangesinValuationAllowanceDetails" xlink:type="extended" id="i7b7a0d28013346b79f4edf329d1c4fd8_IncomeTaxesSummaryofChangesinValuationAllowanceDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceLineItems_7ce06137-36a8-42e5-bdb9-1a082dd28c2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_ac731c60-e96c-46c2-b709-c1b2ddaf4ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_7ce06137-36a8-42e5-bdb9-1a082dd28c2e" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_ac731c60-e96c-46c2-b709-c1b2ddaf4ed8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_67793c4d-f7b8-4094-893d-7e9e9f0852aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_7ce06137-36a8-42e5-bdb9-1a082dd28c2e" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_67793c4d-f7b8-4094-893d-7e9e9f0852aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ValuationAllowanceDeferredTaxAssetIncreaseDecreaseOtherAmount_fff1ea06-eee1-47d5-9a19-765b138bb129" xlink:href="hnst-20211231.xsd#hnst_ValuationAllowanceDeferredTaxAssetIncreaseDecreaseOtherAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_7ce06137-36a8-42e5-bdb9-1a082dd28c2e" xlink:to="loc_hnst_ValuationAllowanceDeferredTaxAssetIncreaseDecreaseOtherAmount_fff1ea06-eee1-47d5-9a19-765b138bb129" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_1abdf6d9-fccd-4753-8426-63d2e5a83b0a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceTable_0ce55133-74f0-4213-975a-eb0d4d4aa19d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ValuationAllowanceLineItems_7ce06137-36a8-42e5-bdb9-1a082dd28c2e" xlink:to="loc_us-gaap_ValuationAllowanceTable_0ce55133-74f0-4213-975a-eb0d4d4aa19d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_94ded6c5-9354-4e84-9f89-616805e2263b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ValuationAllowanceTable_0ce55133-74f0-4213-975a-eb0d4d4aa19d" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_94ded6c5-9354-4e84-9f89-616805e2263b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_94ded6c5-9354-4e84-9f89-616805e2263b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_94ded6c5-9354-4e84-9f89-616805e2263b" xlink:to="loc_us-gaap_TypeOfAdoptionMember_94ded6c5-9354-4e84-9f89-616805e2263b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_14306e9b-ae6f-4214-ba8c-63222b8c0e8c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_94ded6c5-9354-4e84-9f89-616805e2263b" xlink:to="loc_us-gaap_TypeOfAdoptionMember_14306e9b-ae6f-4214-ba8c-63222b8c0e8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate201409Member_952914f1-4f7f-4236-9ee3-f95d60005fd5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_14306e9b-ae6f-4214-ba8c-63222b8c0e8c" xlink:to="loc_us-gaap_AccountingStandardsUpdate201409Member_952914f1-4f7f-4236-9ee3-f95d60005fd5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_b4cb149a-0b6c-4602-8499-59ed050ccc05" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ValuationAllowanceTable_0ce55133-74f0-4213-975a-eb0d4d4aa19d" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_b4cb149a-0b6c-4602-8499-59ed050ccc05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_b4cb149a-0b6c-4602-8499-59ed050ccc05_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_b4cb149a-0b6c-4602-8499-59ed050ccc05" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_b4cb149a-0b6c-4602-8499-59ed050ccc05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_6ea7edaf-f887-4235-b0c5-b4a8008beb8d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_b4cb149a-0b6c-4602-8499-59ed050ccc05" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_6ea7edaf-f887-4235-b0c5-b4a8008beb8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_2923d930-76ee-4dc2-9348-de976ab6066e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_6ea7edaf-f887-4235-b0c5-b4a8008beb8d" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_2923d930-76ee-4dc2-9348-de976ab6066e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="hnst-20211231.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RelatedPartyTransactionsDetails" xlink:type="extended" id="i3fd58700fcbd4eb5b6a4e51b4b871d51_RelatedPartyTransactionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_64bd822a-9461-4a8e-9c61-b01cf81a4372" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingExpense_cf96502c-4bf9-4494-bd83-2fe12b366c46" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_64bd822a-9461-4a8e-9c61-b01cf81a4372" xlink:to="loc_us-gaap_AdvertisingExpense_cf96502c-4bf9-4494-bd83-2fe12b366c46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6c7e5af6-4244-4780-9835-f101f1d6b966" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_64bd822a-9461-4a8e-9c61-b01cf81a4372" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6c7e5af6-4244-4780-9835-f101f1d6b966" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8fcba7a2-e5df-4798-944a-e2722cae9683" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_6c7e5af6-4244-4780-9835-f101f1d6b966" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8fcba7a2-e5df-4798-944a-e2722cae9683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_8fcba7a2-e5df-4798-944a-e2722cae9683_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8fcba7a2-e5df-4798-944a-e2722cae9683" xlink:to="loc_us-gaap_RelatedPartyDomain_8fcba7a2-e5df-4798-944a-e2722cae9683_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_dcc747bf-6203-4fa8-8eaa-2f5bb23113dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_8fcba7a2-e5df-4798-944a-e2722cae9683" xlink:to="loc_us-gaap_RelatedPartyDomain_dcc747bf-6203-4fa8-8eaa-2f5bb23113dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SummitHouseStudiosLLCMember_2a391434-ef18-4c4b-bc97-f1bbd8db3ffc" xlink:href="hnst-20211231.xsd#hnst_SummitHouseStudiosLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_dcc747bf-6203-4fa8-8eaa-2f5bb23113dd" xlink:to="loc_hnst_SummitHouseStudiosLLCMember_2a391434-ef18-4c4b-bc97-f1bbd8db3ffc" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
