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

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:c31be762-2835-47d0-b2a7-247adeda924f,g:880d97e2-fd4a-4957-b8ff-8d7efb69b870-->
<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/CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersDeficit" xlink:type="simple" xlink:href="hnst-20210331.xsd#CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersDeficit"/>
  <link:definitionLink xlink:role="http://honestco.com/role/CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersDeficit" xlink:type="extended" id="iea8de91217de48de8b301f8c9a25d792_CondensedConsolidatedStatementsofRedeemableConvertiblePreferredStockandStockholdersDeficit">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_80e7daa9-db9a-4fdc-a181-e0d14601b615" 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_eeb7b0ea-25d1-47d8-91a2-a1f784509968" 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_80e7daa9-db9a-4fdc-a181-e0d14601b615" xlink:to="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_eeb7b0ea-25d1-47d8-91a2-a1f784509968" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_972bfcf2-6c0b-47e0-9924-f64867b447a3" 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_eeb7b0ea-25d1-47d8-91a2-a1f784509968" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_972bfcf2-6c0b-47e0-9924-f64867b447a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_d29ef26c-214e-497a-83a9-203a038084c4" 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_eeb7b0ea-25d1-47d8-91a2-a1f784509968" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_d29ef26c-214e-497a-83a9-203a038084c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_ff82b400-135f-4d9f-8d98-bdc25105a400" 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_2c2137e8-f48a-4966-be84-62989c862c78" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" 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_80e7daa9-db9a-4fdc-a181-e0d14601b615" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_163ef13e-d54d-41de-80d0-ce891137c604" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_SharesOutstanding_163ef13e-d54d-41de-80d0-ce891137c604" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_8cfae8b6-a13e-4462-b37c-0a8c05a91e57" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_StockholdersEquity_8cfae8b6-a13e-4462-b37c-0a8c05a91e57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_53fa4f60-47e3-4ba7-b523-ebc986e4ff39" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_NetIncomeLoss_53fa4f60-47e3-4ba7-b523-ebc986e4ff39" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_fd99d08f-b820-453c-8ec9-b1b5116fe11e" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_fd99d08f-b820-453c-8ec9-b1b5116fe11e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1cca1200-0f4d-4b79-a69e-d5613bee1fe7" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1cca1200-0f4d-4b79-a69e-d5613bee1fe7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_001e2a32-15f4-4fe8-9a33-eb7788d2414e" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_001e2a32-15f4-4fe8-9a33-eb7788d2414e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_708b64a0-b41e-42b9-b351-5d75799826c7" 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_18152f6e-5540-4263-8fcf-ceb2725cdb57" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_708b64a0-b41e-42b9-b351-5d75799826c7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_8a60dce3-e7c0-44f6-a988-36f29e0c9f3a" 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_aee74707-d0d9-4ff6-8fd3-45d161745184" 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_StatementTable_41f92518-9c4e-46f1-acc0-2accf0c188f0" 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_80e7daa9-db9a-4fdc-a181-e0d14601b615" xlink:to="loc_us-gaap_StatementTable_41f92518-9c4e-46f1-acc0-2accf0c188f0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_74aa4241-711a-483a-9b32-2454b46d2782" 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_41f92518-9c4e-46f1-acc0-2accf0c188f0" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_74aa4241-711a-483a-9b32-2454b46d2782" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_74aa4241-711a-483a-9b32-2454b46d2782_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_74aa4241-711a-483a-9b32-2454b46d2782" xlink:to="loc_us-gaap_EquityComponentDomain_74aa4241-711a-483a-9b32-2454b46d2782_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_7c7362fa-fea8-401b-8173-21badfbb7498" 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_74aa4241-711a-483a-9b32-2454b46d2782" xlink:to="loc_us-gaap_EquityComponentDomain_7c7362fa-fea8-401b-8173-21badfbb7498" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_4e1a6be0-b2eb-45df-99f5-fced431474ed" 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_7c7362fa-fea8-401b-8173-21badfbb7498" xlink:to="loc_us-gaap_CommonStockMember_4e1a6be0-b2eb-45df-99f5-fced431474ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_3831aa0b-9179-442b-bc7b-ab786fd9c055" 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_7c7362fa-fea8-401b-8173-21badfbb7498" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_3831aa0b-9179-442b-bc7b-ab786fd9c055" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_02a21351-e055-4fdd-8b59-40945e869a92" 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_7c7362fa-fea8-401b-8173-21badfbb7498" xlink:to="loc_us-gaap_RetainedEarningsMember_02a21351-e055-4fdd-8b59-40945e869a92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2cd5a613-4333-47d3-8ae7-2adb1a725526" 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_7c7362fa-fea8-401b-8173-21badfbb7498" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_2cd5a613-4333-47d3-8ae7-2adb1a725526" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/NatureofBusinessDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#NatureofBusinessDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/NatureofBusinessDetails" xlink:type="extended" id="iade138fab1324ac3b7d83a696d892554_NatureofBusinessDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockLineItems_1f161f08-a465-4e70-b88f-d990a57c217e" 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_db436c19-553d-46b2-a8c8-b56ca1cfff82" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_db436c19-553d-46b2-a8c8-b56ca1cfff82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_a755bf9b-d7fb-4c6e-941d-0284281256d1" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_a755bf9b-d7fb-4c6e-941d-0284281256d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_1212c65c-6934-4dfd-afe1-c2c515b6ad7f" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_1212c65c-6934-4dfd-afe1-c2c515b6ad7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_d5a913ec-3aa2-440e-8000-4277c99beae6" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_d5a913ec-3aa2-440e-8000-4277c99beae6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_9b720c03-f5c6-49e8-b545-769f3f86fcb7" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_9b720c03-f5c6-49e8-b545-769f3f86fcb7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOfferingCosts_e1b1f1cc-e44d-4b5c-9180-8b74cf337e19" 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_SubsidiarySaleOfStockLineItems_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_DeferredOfferingCosts_e1b1f1cc-e44d-4b5c-9180-8b74cf337e19" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SaleOfStockOptionToPurchaseAdditionalSharesPeriod_57bf542b-22ff-4246-b32b-3e994924451d" xlink:href="hnst-20210331.xsd#hnst_SaleOfStockOptionToPurchaseAdditionalSharesPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsidiarySaleOfStockLineItems_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_hnst_SaleOfStockOptionToPurchaseAdditionalSharesPeriod_57bf542b-22ff-4246-b32b-3e994924451d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_778c495c-bc32-48be-9afc-40561e71e522" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_778c495c-bc32-48be-9afc-40561e71e522" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_719c67e4-e1e1-48c7-9736-6c399c7ef4a9" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_719c67e4-e1e1-48c7-9736-6c399c7ef4a9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_aa1bd09d-c118-420e-8fb7-cdede6e023b9" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_aa1bd09d-c118-420e-8fb7-cdede6e023b9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_0f3d0952-3a79-4195-a7c9-38c73175c5f7" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_0f3d0952-3a79-4195-a7c9-38c73175c5f7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_6e997c76-24f6-4043-9a40-aeefcb4c8a91" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_6e997c76-24f6-4043-9a40-aeefcb4c8a91" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_d1b4eb36-e003-4854-b1b1-7a221998a2f0" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_d1b4eb36-e003-4854-b1b1-7a221998a2f0" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_54736ec0-01eb-47ae-b579-36c4d5e1a685" 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_1f161f08-a465-4e70-b88f-d990a57c217e" xlink:to="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_54736ec0-01eb-47ae-b579-36c4d5e1a685" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_7355a1ca-e3e4-47d8-baa4-b5956ac7e436" 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_54736ec0-01eb-47ae-b579-36c4d5e1a685" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_7355a1ca-e3e4-47d8-baa4-b5956ac7e436" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7355a1ca-e3e4-47d8-baa4-b5956ac7e436_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_7355a1ca-e3e4-47d8-baa4-b5956ac7e436" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7355a1ca-e3e4-47d8-baa4-b5956ac7e436_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_f4f0cc87-4a88-4736-8fb9-63b01da39889" 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_7355a1ca-e3e4-47d8-baa4-b5956ac7e436" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_f4f0cc87-4a88-4736-8fb9-63b01da39889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IPOMember_8b527488-0e9c-4a35-af34-ec7c0941b1b5" 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_f4f0cc87-4a88-4736-8fb9-63b01da39889" xlink:to="loc_us-gaap_IPOMember_8b527488-0e9c-4a35-af34-ec7c0941b1b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_IPOSoldByCompanyMember_dc66e770-0e65-4e6d-bf0a-c2513975c883" xlink:href="hnst-20210331.xsd#hnst_IPOSoldByCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IPOMember_8b527488-0e9c-4a35-af34-ec7c0941b1b5" xlink:to="loc_hnst_IPOSoldByCompanyMember_dc66e770-0e65-4e6d-bf0a-c2513975c883" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_IPOSoldByExistingShareholdersMember_bacc30a5-d182-4fa2-899a-0e6647bc27c1" xlink:href="hnst-20210331.xsd#hnst_IPOSoldByExistingShareholdersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IPOMember_8b527488-0e9c-4a35-af34-ec7c0941b1b5" xlink:to="loc_hnst_IPOSoldByExistingShareholdersMember_bacc30a5-d182-4fa2-899a-0e6647bc27c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_IPOOtherOfferingExpenseMember_e34dc5d4-af8f-4d1e-82aa-a4010d81b5d1" xlink:href="hnst-20210331.xsd#hnst_IPOOtherOfferingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IPOMember_8b527488-0e9c-4a35-af34-ec7c0941b1b5" xlink:to="loc_hnst_IPOOtherOfferingExpenseMember_e34dc5d4-af8f-4d1e-82aa-a4010d81b5d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OverAllotmentOptionMember_fa57f7ef-05a4-44f4-9a83-b7e5e155a624" 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_f4f0cc87-4a88-4736-8fb9-63b01da39889" xlink:to="loc_us-gaap_OverAllotmentOptionMember_fa57f7ef-05a4-44f4-9a83-b7e5e155a624" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_67502c5e-683f-4674-84af-78f93e370c93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsidiaryOrEquityMethodInvesteeSaleOfStockBySubsidiaryOrEquityInvesteeTable_54736ec0-01eb-47ae-b579-36c4d5e1a685" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_67502c5e-683f-4674-84af-78f93e370c93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_67502c5e-683f-4674-84af-78f93e370c93_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_67502c5e-683f-4674-84af-78f93e370c93" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_67502c5e-683f-4674-84af-78f93e370c93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_6cbeb361-105a-4bb1-8c35-d2035678e43a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_67502c5e-683f-4674-84af-78f93e370c93" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_6cbeb361-105a-4bb1-8c35-d2035678e43a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_fb9817d3-b46a-471b-83b5-152ecac843c4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_6cbeb361-105a-4bb1-8c35-d2035678e43a" xlink:to="loc_us-gaap_SubsequentEventMember_fb9817d3-b46a-471b-83b5-152ecac843c4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/SummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#SummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/SummaryofSignificantAccountingPoliciesDetails" xlink:type="extended" id="ia221a9989cd04c9fb920710ae3b57422_SummaryofSignificantAccountingPoliciesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_b7998072-de1a-4f3a-89e1-5c1725ff9cdd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_030a7f9d-b347-49a9-be51-1bb555c19992" 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_SubsequentEventLineItems_b7998072-de1a-4f3a-89e1-5c1725ff9cdd" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_030a7f9d-b347-49a9-be51-1bb555c19992" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_57515f09-503c-40df-b7bc-c0ef8d1b4232" 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_SubsequentEventLineItems_b7998072-de1a-4f3a-89e1-5c1725ff9cdd" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_57515f09-503c-40df-b7bc-c0ef8d1b4232" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOfferingCosts_6cd7144c-e35f-4596-b350-135a012ca534" 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_SubsequentEventLineItems_b7998072-de1a-4f3a-89e1-5c1725ff9cdd" xlink:to="loc_us-gaap_DeferredOfferingCosts_6cd7144c-e35f-4596-b350-135a012ca534" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_915566c8-2bca-4a8f-8733-a23a12bcf498" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_b7998072-de1a-4f3a-89e1-5c1725ff9cdd" xlink:to="loc_us-gaap_SubsequentEventTable_915566c8-2bca-4a8f-8733-a23a12bcf498" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_ded121de-454a-41cb-80ab-ca9436cdf68d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_915566c8-2bca-4a8f-8733-a23a12bcf498" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_ded121de-454a-41cb-80ab-ca9436cdf68d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ded121de-454a-41cb-80ab-ca9436cdf68d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ded121de-454a-41cb-80ab-ca9436cdf68d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ded121de-454a-41cb-80ab-ca9436cdf68d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_fa2ddf5e-5578-48b5-bdc0-d558e2ec00ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ded121de-454a-41cb-80ab-ca9436cdf68d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_fa2ddf5e-5578-48b5-bdc0-d558e2ec00ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_feaf1f10-72e6-4ad0-ad29-878970c2fa71" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_fa2ddf5e-5578-48b5-bdc0-d558e2ec00ea" xlink:to="loc_us-gaap_SubsequentEventMember_feaf1f10-72e6-4ad0-ad29-878970c2fa71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_b57c0780-29aa-4070-a7c9-a351558a453d" 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_SubsequentEventTable_915566c8-2bca-4a8f-8733-a23a12bcf498" xlink:to="loc_us-gaap_StatementClassOfStockAxis_b57c0780-29aa-4070-a7c9-a351558a453d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b57c0780-29aa-4070-a7c9-a351558a453d_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_b57c0780-29aa-4070-a7c9-a351558a453d" xlink:to="loc_us-gaap_ClassOfStockDomain_b57c0780-29aa-4070-a7c9-a351558a453d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_00cec0ee-711d-48a8-900d-979e77072896" 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_b57c0780-29aa-4070-a7c9-a351558a453d" xlink:to="loc_us-gaap_ClassOfStockDomain_00cec0ee-711d-48a8-900d-979e77072896" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_e61dcf15-27f8-4398-8e3d-6b394154b4a1" 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_00cec0ee-711d-48a8-900d-979e77072896" xlink:to="loc_us-gaap_CommonStockMember_e61dcf15-27f8-4398-8e3d-6b394154b4a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_77c7e75c-e23d-4be8-b064-c579bf1fcff1" 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_00cec0ee-711d-48a8-900d-979e77072896" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_77c7e75c-e23d-4be8-b064-c579bf1fcff1" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#RevenueDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="extended" id="i78ff4d991e0248838c823a1b5c6b53db_RevenueDisaggregationofRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_7869d8f4-56ca-46b6-acc9-88ad377717ec" 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_453fd567-0629-4784-b4fa-2e25187b90b9" 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_7869d8f4-56ca-46b6-acc9-88ad377717ec" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_453fd567-0629-4784-b4fa-2e25187b90b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_8e25422c-ede1-46e8-afca-6af96f4cc682" 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_7869d8f4-56ca-46b6-acc9-88ad377717ec" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_8e25422c-ede1-46e8-afca-6af96f4cc682" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_ceed22b6-8070-4333-907e-d5d64acb2703" 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_8e25422c-ede1-46e8-afca-6af96f4cc682" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_ceed22b6-8070-4333-907e-d5d64acb2703" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ceed22b6-8070-4333-907e-d5d64acb2703_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_ceed22b6-8070-4333-907e-d5d64acb2703" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_ceed22b6-8070-4333-907e-d5d64acb2703_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_2eb42c43-a4a7-4dc6-ba70-086905cb6c73" 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_ceed22b6-8070-4333-907e-d5d64acb2703" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_2eb42c43-a4a7-4dc6-ba70-086905cb6c73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DigitalMember_d69551b4-33c0-4044-a013-1feb39f65323" xlink:href="hnst-20210331.xsd#hnst_DigitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_2eb42c43-a4a7-4dc6-ba70-086905cb6c73" xlink:to="loc_hnst_DigitalMember_d69551b4-33c0-4044-a013-1feb39f65323" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetailMember_27bc3ace-e917-40f8-939c-7211526f96c0" 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_2eb42c43-a4a7-4dc6-ba70-086905cb6c73" xlink:to="loc_us-gaap_RetailMember_27bc3ace-e917-40f8-939c-7211526f96c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_f76e630b-e640-4f11-b60c-f81a9783610b" 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_8e25422c-ede1-46e8-afca-6af96f4cc682" xlink:to="loc_srt_ProductOrServiceAxis_f76e630b-e640-4f11-b60c-f81a9783610b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f76e630b-e640-4f11-b60c-f81a9783610b_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_f76e630b-e640-4f11-b60c-f81a9783610b" xlink:to="loc_srt_ProductsAndServicesDomain_f76e630b-e640-4f11-b60c-f81a9783610b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3e99a673-a177-44ce-8669-2b2ebcf233c2" 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_f76e630b-e640-4f11-b60c-f81a9783610b" xlink:to="loc_srt_ProductsAndServicesDomain_3e99a673-a177-44ce-8669-2b2ebcf233c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DiapersAndWipesMember_9189b0f9-8267-412d-947d-c37eecc4b2db" xlink:href="hnst-20210331.xsd#hnst_DiapersAndWipesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3e99a673-a177-44ce-8669-2b2ebcf233c2" xlink:to="loc_hnst_DiapersAndWipesMember_9189b0f9-8267-412d-947d-c37eecc4b2db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SkinAndPersonalCareMember_e8218869-3130-416f-b988-e8f8aee11122" xlink:href="hnst-20210331.xsd#hnst_SkinAndPersonalCareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3e99a673-a177-44ce-8669-2b2ebcf233c2" xlink:to="loc_hnst_SkinAndPersonalCareMember_e8218869-3130-416f-b988-e8f8aee11122" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_HouseholdAndWellnessMember_16eda30b-cd17-42fa-be5a-64c3ddef4486" xlink:href="hnst-20210331.xsd#hnst_HouseholdAndWellnessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3e99a673-a177-44ce-8669-2b2ebcf233c2" xlink:to="loc_hnst_HouseholdAndWellnessMember_16eda30b-cd17-42fa-be5a-64c3ddef4486" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RevenueNarrativeDetails" xlink:type="extended" id="ieff026334360475ba10acecbcffa130b_RevenueNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" 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_8741f70a-5f7b-4706-aa91-ae8463b026e0" 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_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_us-gaap_ContractWithCustomerAssetNet_8741f70a-5f7b-4706-aa91-ae8463b026e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetPeriod_c759d26b-1dd8-4a1b-910c-d66ead546b27" xlink:href="hnst-20210331.xsd#hnst_ContractWithCustomerAssetPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_hnst_ContractWithCustomerAssetPeriod_c759d26b-1dd8-4a1b-910c-d66ead546b27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetExtensionPeriod_5d387f94-94a9-44a6-9b3a-59da8810ed2c" xlink:href="hnst-20210331.xsd#hnst_ContractWithCustomerAssetExtensionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_hnst_ContractWithCustomerAssetExtensionPeriod_5d387f94-94a9-44a6-9b3a-59da8810ed2c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_8b79af2e-4a92-4d4b-b377-89f450ada3cb" 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_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_8b79af2e-4a92-4d4b-b377-89f450ada3cb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_62e0c86c-0e41-4f1e-a7c8-ebeb2a9382df" 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_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_us-gaap_CostOfRevenue_62e0c86c-0e41-4f1e-a7c8-ebeb2a9382df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetImpairment_b1cf209a-7810-4616-b43a-54452ed48ab0" xlink:href="hnst-20210331.xsd#hnst_ContractWithCustomerAssetImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_hnst_ContractWithCustomerAssetImpairment_b1cf209a-7810-4616-b43a-54452ed48ab0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ContractWithCustomerAssetReclassifiedToRevenue_b7cb6b24-5086-4253-969b-31b75001aab7" xlink:href="hnst-20210331.xsd#hnst_ContractWithCustomerAssetReclassifiedToRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_hnst_ContractWithCustomerAssetReclassifiedToRevenue_b7cb6b24-5086-4253-969b-31b75001aab7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_112e526e-bd6f-4403-80ce-a99a7936386b" 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_30d07ef0-ca2e-4bfb-bae9-27268ca964ce" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_112e526e-bd6f-4403-80ce-a99a7936386b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_bdc9101b-08df-4095-a595-80592c829d9a" 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_112e526e-bd6f-4403-80ce-a99a7936386b" xlink:to="loc_srt_ProductOrServiceAxis_bdc9101b-08df-4095-a595-80592c829d9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_bdc9101b-08df-4095-a595-80592c829d9a_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_bdc9101b-08df-4095-a595-80592c829d9a" xlink:to="loc_srt_ProductsAndServicesDomain_bdc9101b-08df-4095-a595-80592c829d9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2716fac1-3a62-4f6b-916b-22e72bf14ffd" 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_bdc9101b-08df-4095-a595-80592c829d9a" xlink:to="loc_srt_ProductsAndServicesDomain_2716fac1-3a62-4f6b-916b-22e72bf14ffd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_TradeAgreementsMember_fdca0c01-c500-4f51-8d1a-579e7e8c4d5b" xlink:href="hnst-20210331.xsd#hnst_TradeAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2716fac1-3a62-4f6b-916b-22e72bf14ffd" xlink:to="loc_hnst_TradeAgreementsMember_fdca0c01-c500-4f51-8d1a-579e7e8c4d5b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#InvestmentsAvailableforSaleInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/InvestmentsAvailableforSaleInvestmentsDetails" xlink:type="extended" id="i545e81c7f76b4496837991a61772bcdd_InvestmentsAvailableforSaleInvestmentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_943369c0-8659-4c1e-8330-33ff8b0991af" 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_42f57c28-7680-469c-9e05-d782e4924df7" 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_943369c0-8659-4c1e-8330-33ff8b0991af" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_42f57c28-7680-469c-9e05-d782e4924df7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_e4afb642-1b6b-4eec-b63e-6334d912d386" 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_943369c0-8659-4c1e-8330-33ff8b0991af" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_e4afb642-1b6b-4eec-b63e-6334d912d386" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_a3862da2-e938-455d-95f9-65eaf346498a" 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_943369c0-8659-4c1e-8330-33ff8b0991af" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_a3862da2-e938-455d-95f9-65eaf346498a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_45aa7d43-0be3-4c82-8683-3db9cb08ecce" 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_943369c0-8659-4c1e-8330-33ff8b0991af" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_45aa7d43-0be3-4c82-8683-3db9cb08ecce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_fa9c052c-8c97-4dc2-b964-9a0eb19c1219" 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_943369c0-8659-4c1e-8330-33ff8b0991af" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_fa9c052c-8c97-4dc2-b964-9a0eb19c1219" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_f9016f02-2cce-4bc0-8e12-911a8acf749d" 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_fa9c052c-8c97-4dc2-b964-9a0eb19c1219" xlink:to="loc_us-gaap_FinancialInstrumentAxis_f9016f02-2cce-4bc0-8e12-911a8acf749d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f9016f02-2cce-4bc0-8e12-911a8acf749d_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_f9016f02-2cce-4bc0-8e12-911a8acf749d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f9016f02-2cce-4bc0-8e12-911a8acf749d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_74b15861-694f-40f3-b180-0238026632f4" 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_f9016f02-2cce-4bc0-8e12-911a8acf749d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_74b15861-694f-40f3-b180-0238026632f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_52666911-0495-42a9-9651-14e1c0e9fe4e" 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_74b15861-694f-40f3-b180-0238026632f4" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_52666911-0495-42a9-9651-14e1c0e9fe4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_eb08f05c-ff35-4af4-9960-02c492a9016b" 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_74b15861-694f-40f3-b180-0238026632f4" xlink:to="loc_us-gaap_CommercialPaperMember_eb08f05c-ff35-4af4-9960-02c492a9016b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_af2ee9cd-518e-4885-9dbe-5501fb295401" 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_74b15861-694f-40f3-b180-0238026632f4" xlink:to="loc_us-gaap_CertificatesOfDepositMember_af2ee9cd-518e-4885-9dbe-5501fb295401" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryAndGovernmentMember_eb88be34-14e2-46a4-b6ec-7038cf64655a" 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_74b15861-694f-40f3-b180-0238026632f4" xlink:to="loc_us-gaap_USTreasuryAndGovernmentMember_eb88be34-14e2-46a4-b6ec-7038cf64655a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#FairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/FairValueMeasurementsDetails" xlink:type="extended" id="ib67ec4690f3d401782b66ecbdda4fdbb_FairValueMeasurementsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_fd48d711-8b09-4fe6-ad62-679e53b11d92" 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_c092f446-55ce-43ff-9b38-29614c97311f" 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_fd48d711-8b09-4fe6-ad62-679e53b11d92" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_c092f446-55ce-43ff-9b38-29614c97311f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_a23188dc-daa9-4e7e-9f24-89abbae00b3c" 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_fd48d711-8b09-4fe6-ad62-679e53b11d92" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_a23188dc-daa9-4e7e-9f24-89abbae00b3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_eafcdf92-ce07-461a-8050-8365dd43e453" 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_fd48d711-8b09-4fe6-ad62-679e53b11d92" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_eafcdf92-ce07-461a-8050-8365dd43e453" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_9e8a1173-8811-4e3a-acb0-afecb69c7f7e" 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_fd48d711-8b09-4fe6-ad62-679e53b11d92" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_9e8a1173-8811-4e3a-acb0-afecb69c7f7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1da67a90-f1ef-416b-8269-5c85aced2106" 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_9e8a1173-8811-4e3a-acb0-afecb69c7f7e" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1da67a90-f1ef-416b-8269-5c85aced2106" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1da67a90-f1ef-416b-8269-5c85aced2106_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_1da67a90-f1ef-416b-8269-5c85aced2106" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1da67a90-f1ef-416b-8269-5c85aced2106_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_33297f78-e94a-4afd-8e9e-d2d9d5d7bff5" 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_1da67a90-f1ef-416b-8269-5c85aced2106" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_33297f78-e94a-4afd-8e9e-d2d9d5d7bff5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_56bb6758-2be1-4b2e-9cf8-2cb6cf3a64f2" 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_33297f78-e94a-4afd-8e9e-d2d9d5d7bff5" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_56bb6758-2be1-4b2e-9cf8-2cb6cf3a64f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1b575e04-990e-4881-a63d-603abf0c0c7c" 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_9e8a1173-8811-4e3a-acb0-afecb69c7f7e" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1b575e04-990e-4881-a63d-603abf0c0c7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b575e04-990e-4881-a63d-603abf0c0c7c_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_1b575e04-990e-4881-a63d-603abf0c0c7c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1b575e04-990e-4881-a63d-603abf0c0c7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_34c36b7b-13f9-4dcf-b43e-84dafd4ad420" 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_1b575e04-990e-4881-a63d-603abf0c0c7c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_34c36b7b-13f9-4dcf-b43e-84dafd4ad420" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_e2300ec4-4fe0-4315-90b1-d56ef111fae2" 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_34c36b7b-13f9-4dcf-b43e-84dafd4ad420" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_e2300ec4-4fe0-4315-90b1-d56ef111fae2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_e43d0c03-0a79-491d-98c9-18fcec661016" 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_34c36b7b-13f9-4dcf-b43e-84dafd4ad420" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_e43d0c03-0a79-491d-98c9-18fcec661016" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_b7e388b3-dd4e-4c15-8eb6-c95da7a8937c" 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_34c36b7b-13f9-4dcf-b43e-84dafd4ad420" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_b7e388b3-dd4e-4c15-8eb6-c95da7a8937c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_3d550181-5930-4b61-9231-e89e9219ccc6" 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_9e8a1173-8811-4e3a-acb0-afecb69c7f7e" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_3d550181-5930-4b61-9231-e89e9219ccc6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3d550181-5930-4b61-9231-e89e9219ccc6_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_3d550181-5930-4b61-9231-e89e9219ccc6" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_3d550181-5930-4b61-9231-e89e9219ccc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_d09e8788-9bf2-4d96-a7ae-6dd441d51c3f" 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_3d550181-5930-4b61-9231-e89e9219ccc6" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_d09e8788-9bf2-4d96-a7ae-6dd441d51c3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_9206163c-d067-431e-bbe2-6dfb86ae7e7e" 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_d09e8788-9bf2-4d96-a7ae-6dd441d51c3f" xlink:to="loc_us-gaap_MoneyMarketFundsMember_9206163c-d067-431e-bbe2-6dfb86ae7e7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_40a5cb22-a772-45e3-99be-8199e374949d" 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_9e8a1173-8811-4e3a-acb0-afecb69c7f7e" xlink:to="loc_us-gaap_FinancialInstrumentAxis_40a5cb22-a772-45e3-99be-8199e374949d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_40a5cb22-a772-45e3-99be-8199e374949d_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_40a5cb22-a772-45e3-99be-8199e374949d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_40a5cb22-a772-45e3-99be-8199e374949d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_258f7682-e7b4-457c-b991-11cd7110c661" 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_40a5cb22-a772-45e3-99be-8199e374949d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_258f7682-e7b4-457c-b991-11cd7110c661" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_148db216-9c2f-409d-ac53-3ae45363623a" 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_258f7682-e7b4-457c-b991-11cd7110c661" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_148db216-9c2f-409d-ac53-3ae45363623a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_49fa753d-9ac3-4dbf-ac86-f2aacb2e11dc" 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_258f7682-e7b4-457c-b991-11cd7110c661" xlink:to="loc_us-gaap_CommercialPaperMember_49fa753d-9ac3-4dbf-ac86-f2aacb2e11dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CertificatesOfDepositMember_598f7185-5e08-4b1c-b129-2200580bff61" 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_258f7682-e7b4-457c-b991-11cd7110c661" xlink:to="loc_us-gaap_CertificatesOfDepositMember_598f7185-5e08-4b1c-b129-2200580bff61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasuryAndGovernmentMember_003e90e7-2c75-417d-ac1f-cf75d518117f" 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_258f7682-e7b4-457c-b991-11cd7110c661" xlink:to="loc_us-gaap_USTreasuryAndGovernmentMember_003e90e7-2c75-417d-ac1f-cf75d518117f" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/CreditFacilitiesDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#CreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/CreditFacilitiesDetails" xlink:type="extended" id="i404871066f114ee28f726ae0314f5a10_CreditFacilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_3937d7b0-f653-4d41-85d8-2507dc4e58a1" 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_e83199a2-7261-4c1c-8b6d-d120116dfb60" 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_3937d7b0-f653-4d41-85d8-2507dc4e58a1" xlink:to="loc_us-gaap_LineOfCredit_e83199a2-7261-4c1c-8b6d-d120116dfb60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_d814ed87-d554-4b9e-a1af-332beb9cd15b" 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_3937d7b0-f653-4d41-85d8-2507dc4e58a1" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_d814ed87-d554-4b9e-a1af-332beb9cd15b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_aa234e0b-1c4e-4b2e-8d5d-9e807ad2e4ec" 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_3937d7b0-f653-4d41-85d8-2507dc4e58a1" xlink:to="loc_us-gaap_RestrictedCash_aa234e0b-1c4e-4b2e-8d5d-9e807ad2e4ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_454779e7-7a8a-419e-af5c-40b84d44da08" 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_3937d7b0-f653-4d41-85d8-2507dc4e58a1" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_454779e7-7a8a-419e-af5c-40b84d44da08" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_87ec56b6-f996-433f-8624-5c660d57c455" 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_454779e7-7a8a-419e-af5c-40b84d44da08" xlink:to="loc_us-gaap_DebtInstrumentAxis_87ec56b6-f996-433f-8624-5c660d57c455" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_87ec56b6-f996-433f-8624-5c660d57c455_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_87ec56b6-f996-433f-8624-5c660d57c455" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_87ec56b6-f996-433f-8624-5c660d57c455_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d286cb61-b7bd-4705-9e60-e9c4d96286ad" 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_87ec56b6-f996-433f-8624-5c660d57c455" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d286cb61-b7bd-4705-9e60-e9c4d96286ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_AssetBackedLoanFacilityMember_309acbbf-2bb3-4841-a315-ea57b4ca6232" xlink:href="hnst-20210331.xsd#hnst_AssetBackedLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_d286cb61-b7bd-4705-9e60-e9c4d96286ad" xlink:to="loc_hnst_AssetBackedLoanFacilityMember_309acbbf-2bb3-4841-a315-ea57b4ca6232" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_54da5bee-2258-4981-8249-1c969cd65c9d" 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_454779e7-7a8a-419e-af5c-40b84d44da08" xlink:to="loc_us-gaap_CreditFacilityAxis_54da5bee-2258-4981-8249-1c969cd65c9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_54da5bee-2258-4981-8249-1c969cd65c9d_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_54da5bee-2258-4981-8249-1c969cd65c9d" xlink:to="loc_us-gaap_CreditFacilityDomain_54da5bee-2258-4981-8249-1c969cd65c9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_fdbb9c2c-748f-4557-9bf3-fc8575ac04cc" 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_54da5bee-2258-4981-8249-1c969cd65c9d" xlink:to="loc_us-gaap_CreditFacilityDomain_fdbb9c2c-748f-4557-9bf3-fc8575ac04cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_a033b8e9-a613-4745-ac60-041783757755" 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_fdbb9c2c-748f-4557-9bf3-fc8575ac04cc" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_a033b8e9-a613-4745-ac60-041783757755" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_8b0c6f30-5038-444d-8c81-a52bcf5c0faa" 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_454779e7-7a8a-419e-af5c-40b84d44da08" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_8b0c6f30-5038-444d-8c81-a52bcf5c0faa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8b0c6f30-5038-444d-8c81-a52bcf5c0faa_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_8b0c6f30-5038-444d-8c81-a52bcf5c0faa" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8b0c6f30-5038-444d-8c81-a52bcf5c0faa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_20213569-1c39-47c1-9885-897dd6fedc4c" 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_8b0c6f30-5038-444d-8c81-a52bcf5c0faa" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_20213569-1c39-47c1-9885-897dd6fedc4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_3f46f61d-d60a-436b-b833-4d72b0502ff8" 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_20213569-1c39-47c1-9885-897dd6fedc4c" xlink:to="loc_us-gaap_LineOfCreditMember_3f46f61d-d60a-436b-b833-4d72b0502ff8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/CommitmentsandContingenciesDetails" xlink:type="extended" id="ib80fd8f5e9984ea0a65a890c4b3091ab_CommitmentsandContingenciesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_6d14aa9f-d2e7-49d6-b3ea-fa269a8ed07d" 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_8fb9d42e-7b33-4830-af7a-c7efe60fe29f" 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_6d14aa9f-d2e7-49d6-b3ea-fa269a8ed07d" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_8fb9d42e-7b33-4830-af7a-c7efe60fe29f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_4fbd86a9-4671-4d94-8528-23b6db7e0e42" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_6d14aa9f-d2e7-49d6-b3ea-fa269a8ed07d" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_4fbd86a9-4671-4d94-8528-23b6db7e0e42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_22c8004a-456b-4127-8b67-2f148ad6e2da" 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_6d14aa9f-d2e7-49d6-b3ea-fa269a8ed07d" xlink:to="loc_us-gaap_LossContingenciesTable_22c8004a-456b-4127-8b67-2f148ad6e2da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_fc7ded11-fb50-4fea-bb8c-e8d90e8d19b9" 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_22c8004a-456b-4127-8b67-2f148ad6e2da" xlink:to="loc_srt_LitigationCaseAxis_fc7ded11-fb50-4fea-bb8c-e8d90e8d19b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_fc7ded11-fb50-4fea-bb8c-e8d90e8d19b9_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_fc7ded11-fb50-4fea-bb8c-e8d90e8d19b9" xlink:to="loc_srt_LitigationCaseTypeDomain_fc7ded11-fb50-4fea-bb8c-e8d90e8d19b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_5553663c-c888-42d4-b839-e463de9cf177" 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_fc7ded11-fb50-4fea-bb8c-e8d90e8d19b9" xlink:to="loc_srt_LitigationCaseTypeDomain_5553663c-c888-42d4-b839-e463de9cf177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_NevadaDepartmentOfTaxationVsTheHonestCompanyIncMember_dd2ccb04-923f-41de-8398-b60851b05c51" xlink:href="hnst-20210331.xsd#hnst_NevadaDepartmentOfTaxationVsTheHonestCompanyIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_5553663c-c888-42d4-b839-e463de9cf177" xlink:to="loc_hnst_NevadaDepartmentOfTaxationVsTheHonestCompanyIncMember_dd2ccb04-923f-41de-8398-b60851b05c51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_b4377c87-6526-4e3d-9867-0f7e6fe3f1c8" 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_22c8004a-456b-4127-8b67-2f148ad6e2da" xlink:to="loc_us-gaap_LitigationStatusAxis_b4377c87-6526-4e3d-9867-0f7e6fe3f1c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_b4377c87-6526-4e3d-9867-0f7e6fe3f1c8_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_b4377c87-6526-4e3d-9867-0f7e6fe3f1c8" xlink:to="loc_us-gaap_LitigationStatusDomain_b4377c87-6526-4e3d-9867-0f7e6fe3f1c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_51d0a760-a496-40c3-8398-6939554dbbce" 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_b4377c87-6526-4e3d-9867-0f7e6fe3f1c8" xlink:to="loc_us-gaap_LitigationStatusDomain_51d0a760-a496-40c3-8398-6939554dbbce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_ef558287-5a9c-4305-9ee1-20fd0f3e9f70" 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_51d0a760-a496-40c3-8398-6939554dbbce" xlink:to="loc_us-gaap_PendingLitigationMember_ef558287-5a9c-4305-9ee1-20fd0f3e9f70" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#StockBasedCompensationStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationStockbasedCompensationExpenseDetails" xlink:type="extended" id="i51321d3c7d0d4f37b2cb60aee0b6e3c1_StockBasedCompensationStockbasedCompensationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_d6c9a8d2-ed78-47b3-a2d5-24561c024a9c" 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_fb21106e-2898-4db3-9d55-115e8685280c" 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_d6c9a8d2-ed78-47b3-a2d5-24561c024a9c" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_fb21106e-2898-4db3-9d55-115e8685280c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_d64f497e-dadb-44cf-925a-c2cc721dbb93" 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_d6c9a8d2-ed78-47b3-a2d5-24561c024a9c" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_d64f497e-dadb-44cf-925a-c2cc721dbb93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_2862a27a-ab85-42b7-9028-05f3936b5088" 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_d64f497e-dadb-44cf-925a-c2cc721dbb93" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_2862a27a-ab85-42b7-9028-05f3936b5088" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_2862a27a-ab85-42b7-9028-05f3936b5088_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_2862a27a-ab85-42b7-9028-05f3936b5088" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_2862a27a-ab85-42b7-9028-05f3936b5088_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_fa5c3db7-6c4e-4a34-96b4-8ea382699fd2" 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_2862a27a-ab85-42b7-9028-05f3936b5088" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_fa5c3db7-6c4e-4a34-96b4-8ea382699fd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_b8fd05a2-1255-471e-b0e5-b3e21ea315ea" 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_fa5c3db7-6c4e-4a34-96b4-8ea382699fd2" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_b8fd05a2-1255-471e-b0e5-b3e21ea315ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_74e5601b-5b12-4c55-b0b9-71e1097ea412" 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_fa5c3db7-6c4e-4a34-96b4-8ea382699fd2" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_74e5601b-5b12-4c55-b0b9-71e1097ea412" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails" xlink:type="extended" id="i45843acba8d149379499029f57eaa46d_StockBasedCompensationScheduleofSharebasedPaymentAwardStockOptionsValuationAssumptionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" 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_bad260b0-ea9a-42a3-9e10-f29f39f8f5e3" 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_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_bad260b0-ea9a-42a3-9e10-f29f39f8f5e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_f9941fd8-c4d2-4cb9-9b01-7658e237381a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_f9941fd8-c4d2-4cb9-9b01-7658e237381a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_1b9fef6d-67b2-4bc8-85c5-3feb7e145c30" 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_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_1b9fef6d-67b2-4bc8-85c5-3feb7e145c30" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_02ffea83-54c4-4450-ae09-1d594a7a751f" 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_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_02ffea83-54c4-4450-ae09-1d594a7a751f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_6f270dc4-69b1-46cb-bf38-7f53ec6661f0" 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_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_6f270dc4-69b1-46cb-bf38-7f53ec6661f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_aad4a00b-3cf4-4c17-9dd7-f899eb621a8d" 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_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_aad4a00b-3cf4-4c17-9dd7-f899eb621a8d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2fc275c6-bf51-4f8d-a4e1-a675c6914333" 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_a41d52fa-c0be-4dc6-94f1-3e82d9721a7b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2fc275c6-bf51-4f8d-a4e1-a675c6914333" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_567d4382-41fc-4c9f-ba50-88136d7e3ed0" 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_2fc275c6-bf51-4f8d-a4e1-a675c6914333" xlink:to="loc_srt_RangeAxis_567d4382-41fc-4c9f-ba50-88136d7e3ed0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_567d4382-41fc-4c9f-ba50-88136d7e3ed0_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_567d4382-41fc-4c9f-ba50-88136d7e3ed0" xlink:to="loc_srt_RangeMember_567d4382-41fc-4c9f-ba50-88136d7e3ed0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a877737b-e81c-4417-88ae-b0d928d5ec1c" 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_567d4382-41fc-4c9f-ba50-88136d7e3ed0" xlink:to="loc_srt_RangeMember_a877737b-e81c-4417-88ae-b0d928d5ec1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_8620cf65-c4c4-4a9e-8281-d755a5a07109" 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_a877737b-e81c-4417-88ae-b0d928d5ec1c" xlink:to="loc_srt_MinimumMember_8620cf65-c4c4-4a9e-8281-d755a5a07109" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_4c56cff5-d473-4e98-8a0e-d71c608c10e5" 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_a877737b-e81c-4417-88ae-b0d928d5ec1c" xlink:to="loc_srt_MaximumMember_4c56cff5-d473-4e98-8a0e-d71c608c10e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_b7a9abcf-c768-4f91-9882-bbec8027d0ce" 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_2fc275c6-bf51-4f8d-a4e1-a675c6914333" xlink:to="loc_us-gaap_AwardTypeAxis_b7a9abcf-c768-4f91-9882-bbec8027d0ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b7a9abcf-c768-4f91-9882-bbec8027d0ce_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_b7a9abcf-c768-4f91-9882-bbec8027d0ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b7a9abcf-c768-4f91-9882-bbec8027d0ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7da537f2-68f4-452a-8b63-018c7b1a8076" 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_b7a9abcf-c768-4f91-9882-bbec8027d0ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7da537f2-68f4-452a-8b63-018c7b1a8076" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_73e442dc-808d-43e1-b9bf-adc1ad3af09d" 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_7da537f2-68f4-452a-8b63-018c7b1a8076" xlink:to="loc_us-gaap_EmployeeStockOptionMember_73e442dc-808d-43e1-b9bf-adc1ad3af09d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationPerformanceandMarketVestingConditionsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#StockBasedCompensationPerformanceandMarketVestingConditionsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationPerformanceandMarketVestingConditionsDetails" xlink:type="extended" id="i8b219508cb344574acc9b5bbabc50f20_StockBasedCompensationPerformanceandMarketVestingConditionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aa7c571b-140e-47ec-99d0-590fe9fa88aa" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_00e75fd0-690e-425e-8f60-609b6512863a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_00e75fd0-690e-425e-8f60-609b6512863a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_28bf0aa1-23f6-4f9a-8ec8-27683cf00292" 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_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_28bf0aa1-23f6-4f9a-8ec8-27683cf00292" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_d07c9102-17cf-457a-bb7f-ae3ef121b38c" 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_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_d07c9102-17cf-457a-bb7f-ae3ef121b38c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_0485f68b-1229-48c0-bf5c-25b42671185b" 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_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_0485f68b-1229-48c0-bf5c-25b42671185b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_96f4fe5b-87b0-405a-8c87-a5999cc191cd" 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_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_96f4fe5b-87b0-405a-8c87-a5999cc191cd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_1c23a285-283a-47a5-a54b-291643f24543" 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_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_1c23a285-283a-47a5-a54b-291643f24543" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardBenchmarkToVestNetRevenue_f29e2ea3-82e6-4021-ae92-937a1fa8f30d" xlink:href="hnst-20210331.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardBenchmarkToVestNetRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardBenchmarkToVestNetRevenue_f29e2ea3-82e6-4021-ae92-937a1fa8f30d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardBenchmarkToVestEBITDA_7e1d0910-abde-4ffa-9b68-ecffc48df920" xlink:href="hnst-20210331.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardBenchmarkToVestEBITDA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardBenchmarkToVestEBITDA_7e1d0910-abde-4ffa-9b68-ecffc48df920" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingBenchmarkMultiplier_3629f5f9-e596-46a1-a52b-63d2d7b4879f" xlink:href="hnst-20210331.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingBenchmarkMultiplier"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingBenchmarkMultiplier_3629f5f9-e596-46a1-a52b-63d2d7b4879f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_b7be870c-b025-46fa-b126-252ac5048bb9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_b7be870c-b025-46fa-b126-252ac5048bb9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_620336f2-0f3a-4b5b-a799-c92df87b6311" 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_aa7c571b-140e-47ec-99d0-590fe9fa88aa" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_620336f2-0f3a-4b5b-a799-c92df87b6311" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_e1d0027b-a1d6-472e-a60c-039cfd44a20f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_620336f2-0f3a-4b5b-a799-c92df87b6311" xlink:to="loc_us-gaap_VestingAxis_e1d0027b-a1d6-472e-a60c-039cfd44a20f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_e1d0027b-a1d6-472e-a60c-039cfd44a20f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_e1d0027b-a1d6-472e-a60c-039cfd44a20f" xlink:to="loc_us-gaap_VestingDomain_e1d0027b-a1d6-472e-a60c-039cfd44a20f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_85458d5d-3cf8-452b-830b-f2b4e2954cca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_e1d0027b-a1d6-472e-a60c-039cfd44a20f" xlink:to="loc_us-gaap_VestingDomain_85458d5d-3cf8-452b-830b-f2b4e2954cca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_a9e57c81-fa61-4571-a9a6-db7649a1cf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_85458d5d-3cf8-452b-830b-f2b4e2954cca" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_a9e57c81-fa61-4571-a9a6-db7649a1cf3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_d2bd7a4e-c3c1-4efd-bcfb-a0491e3230fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_85458d5d-3cf8-452b-830b-f2b4e2954cca" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_d2bd7a4e-c3c1-4efd-bcfb-a0491e3230fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_4a2dc395-a59a-4c6b-8a20-62313bb89d7c" 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_620336f2-0f3a-4b5b-a799-c92df87b6311" xlink:to="loc_us-gaap_AwardTypeAxis_4a2dc395-a59a-4c6b-8a20-62313bb89d7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4a2dc395-a59a-4c6b-8a20-62313bb89d7c_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_4a2dc395-a59a-4c6b-8a20-62313bb89d7c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4a2dc395-a59a-4c6b-8a20-62313bb89d7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30ecc949-15de-406b-9da7-4329856dc034" 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_4a2dc395-a59a-4c6b-8a20-62313bb89d7c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30ecc949-15de-406b-9da7-4329856dc034" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_StockOptionsWithLiquidityEventVestingConditionsMember_b0f31c7c-b2d9-4ace-9562-9bc163adf4e3" xlink:href="hnst-20210331.xsd#hnst_StockOptionsWithLiquidityEventVestingConditionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30ecc949-15de-406b-9da7-4329856dc034" xlink:to="loc_hnst_StockOptionsWithLiquidityEventVestingConditionsMember_b0f31c7c-b2d9-4ace-9562-9bc163adf4e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_PerformanceBasedOptionsMember_bef9714a-fe33-4621-8f63-166405fa2ab5" xlink:href="hnst-20210331.xsd#hnst_PerformanceBasedOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30ecc949-15de-406b-9da7-4329856dc034" xlink:to="loc_hnst_PerformanceBasedOptionsMember_bef9714a-fe33-4621-8f63-166405fa2ab5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ModifiedAwardMember_41e9f7bd-8c9c-4750-9497-940a66cf65fe" xlink:href="hnst-20210331.xsd#hnst_ModifiedAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30ecc949-15de-406b-9da7-4329856dc034" xlink:to="loc_hnst_ModifiedAwardMember_41e9f7bd-8c9c-4750-9497-940a66cf65fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_065550e8-dedf-46ed-8b65-6aed6a1b482a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_620336f2-0f3a-4b5b-a799-c92df87b6311" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_065550e8-dedf-46ed-8b65-6aed6a1b482a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_065550e8-dedf-46ed-8b65-6aed6a1b482a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_065550e8-dedf-46ed-8b65-6aed6a1b482a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_065550e8-dedf-46ed-8b65-6aed6a1b482a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_1336747d-ec75-4abf-803d-e64e23bbd45c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_065550e8-dedf-46ed-8b65-6aed6a1b482a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_1336747d-ec75-4abf-803d-e64e23bbd45c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_46562438-b3b1-4242-9fdb-478586ce3f9c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_1336747d-ec75-4abf-803d-e64e23bbd45c" xlink:to="loc_us-gaap_SubsequentEventMember_46562438-b3b1-4242-9fdb-478586ce3f9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_3eca5a3a-fa15-435c-acd6-681ce4e6b78d" 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_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_620336f2-0f3a-4b5b-a799-c92df87b6311" xlink:to="loc_srt_StatementScenarioAxis_3eca5a3a-fa15-435c-acd6-681ce4e6b78d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_3eca5a3a-fa15-435c-acd6-681ce4e6b78d_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_3eca5a3a-fa15-435c-acd6-681ce4e6b78d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_3eca5a3a-fa15-435c-acd6-681ce4e6b78d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_601ca7f7-8ccf-4307-8a6f-1ad697906a72" 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_3eca5a3a-fa15-435c-acd6-681ce4e6b78d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_601ca7f7-8ccf-4307-8a6f-1ad697906a72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_2c1e40c3-a7ea-4507-8eb4-288467bb4afe" 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_601ca7f7-8ccf-4307-8a6f-1ad697906a72" xlink:to="loc_srt_ScenarioForecastMember_2c1e40c3-a7ea-4507-8eb4-288467bb4afe" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/StockBasedCompensationRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#StockBasedCompensationRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/StockBasedCompensationRestrictedStockUnitsDetails" xlink:type="extended" id="i6b21cc27bd4f4a088defe7f869000280_StockBasedCompensationRestrictedStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b63c2919-54ee-4256-a204-2bd32dfb6743" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_a7a4152d-c9ad-4d11-a166-24cba9e5defa" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b63c2919-54ee-4256-a204-2bd32dfb6743" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_a7a4152d-c9ad-4d11-a166-24cba9e5defa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_68e49dfa-9320-4df3-827f-7a5bfa84326e" 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_b63c2919-54ee-4256-a204-2bd32dfb6743" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_68e49dfa-9320-4df3-827f-7a5bfa84326e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue_6bf32cd9-31a3-4950-96d4-002718a3d1b9" xlink:href="hnst-20210331.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b63c2919-54ee-4256-a204-2bd32dfb6743" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue_6bf32cd9-31a3-4950-96d4-002718a3d1b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_a44364f1-f0a6-411d-8422-853036f9ccb4" 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_b63c2919-54ee-4256-a204-2bd32dfb6743" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_a44364f1-f0a6-411d-8422-853036f9ccb4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97bbfdde-b929-4f16-80d8-0cc8484bc3d1" 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_b63c2919-54ee-4256-a204-2bd32dfb6743" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97bbfdde-b929-4f16-80d8-0cc8484bc3d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_de5dc9d9-8ab6-43b1-8abb-053e0fd6a2db" 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_97bbfdde-b929-4f16-80d8-0cc8484bc3d1" xlink:to="loc_us-gaap_AwardTypeAxis_de5dc9d9-8ab6-43b1-8abb-053e0fd6a2db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_de5dc9d9-8ab6-43b1-8abb-053e0fd6a2db_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_de5dc9d9-8ab6-43b1-8abb-053e0fd6a2db" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_de5dc9d9-8ab6-43b1-8abb-053e0fd6a2db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bf4e0002-2a53-410b-a7f2-7fa992ba3f44" 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_de5dc9d9-8ab6-43b1-8abb-053e0fd6a2db" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bf4e0002-2a53-410b-a7f2-7fa992ba3f44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_cc5b018d-54a2-4a6c-ad4a-a668c74c3204" 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_bf4e0002-2a53-410b-a7f2-7fa992ba3f44" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_cc5b018d-54a2-4a6c-ad4a-a668c74c3204" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_RSUsContinuedServiceAwardsMember_2371ad13-476b-4a64-91b5-b9ef468277e6" xlink:href="hnst-20210331.xsd#hnst_RSUsContinuedServiceAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember_cc5b018d-54a2-4a6c-ad4a-a668c74c3204" xlink:to="loc_hnst_RSUsContinuedServiceAwardsMember_2371ad13-476b-4a64-91b5-b9ef468277e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_RSUsAwardsFromOccurrenceOfALiquidityEventMember_06b51711-6459-4be3-90cb-fe0b0c03cb1f" xlink:href="hnst-20210331.xsd#hnst_RSUsAwardsFromOccurrenceOfALiquidityEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember_cc5b018d-54a2-4a6c-ad4a-a668c74c3204" xlink:to="loc_hnst_RSUsAwardsFromOccurrenceOfALiquidityEventMember_06b51711-6459-4be3-90cb-fe0b0c03cb1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_64bec6e8-90e9-4628-8fd9-53b18d452a58" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97bbfdde-b929-4f16-80d8-0cc8484bc3d1" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_64bec6e8-90e9-4628-8fd9-53b18d452a58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_64bec6e8-90e9-4628-8fd9-53b18d452a58_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_64bec6e8-90e9-4628-8fd9-53b18d452a58" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_64bec6e8-90e9-4628-8fd9-53b18d452a58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_24021b11-747b-4a89-a54a-386a64e1b28d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_64bec6e8-90e9-4628-8fd9-53b18d452a58" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_24021b11-747b-4a89-a54a-386a64e1b28d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_feea1b53-1510-4894-8d78-4e5fe05d57c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_24021b11-747b-4a89-a54a-386a64e1b28d" xlink:to="loc_us-gaap_SubsequentEventMember_feea1b53-1510-4894-8d78-4e5fe05d57c0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails" xlink:type="extended" id="i1d64cf7304e24bd780ede2beb553969a_NetIncomeLossperShareAttributabletoCommonStockholdersPotentiallyDilutiveSharesExcludedFromComputationofDilutedNetIncomeLossPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_8cb9fad7-6276-4e8e-9599-0bccb63a0b5b" 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_4e666825-aee8-4676-bf3c-36e708042eda" 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_8cb9fad7-6276-4e8e-9599-0bccb63a0b5b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_4e666825-aee8-4676-bf3c-36e708042eda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_45e02f4a-946e-45c8-a1ba-08923b8d9e1a" 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_8cb9fad7-6276-4e8e-9599-0bccb63a0b5b" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_45e02f4a-946e-45c8-a1ba-08923b8d9e1a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_514015d5-8c00-4902-9503-02c93c1c5219" 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_45e02f4a-946e-45c8-a1ba-08923b8d9e1a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_514015d5-8c00-4902-9503-02c93c1c5219" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_514015d5-8c00-4902-9503-02c93c1c5219_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_514015d5-8c00-4902-9503-02c93c1c5219" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_514015d5-8c00-4902-9503-02c93c1c5219_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6c503c27-8a9c-4e25-9d72-325e53ce4a4f" 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_514015d5-8c00-4902-9503-02c93c1c5219" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_6c503c27-8a9c-4e25-9d72-325e53ce4a4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemableConvertiblePreferredStockMember_cb380b7f-790a-462b-a88c-5b53bdec7377" 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_6c503c27-8a9c-4e25-9d72-325e53ce4a4f" xlink:to="loc_us-gaap_RedeemableConvertiblePreferredStockMember_cb380b7f-790a-462b-a88c-5b53bdec7377" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_bfe45cc6-e6bb-4bc0-9657-9cf2846c1d11" 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_6c503c27-8a9c-4e25-9d72-325e53ce4a4f" xlink:to="loc_us-gaap_EmployeeStockOptionMember_bfe45cc6-e6bb-4bc0-9657-9cf2846c1d11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_9a1a2b0f-b9d0-4be4-aef0-2a987dd40896" 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_6c503c27-8a9c-4e25-9d72-325e53ce4a4f" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_9a1a2b0f-b9d0-4be4-aef0-2a987dd40896" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/RelatedPartyTransactionsDetails" xlink:type="extended" id="ifb89e1b0e4c847ffb50435d567e6eef1_RelatedPartyTransactionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_90da5a6d-a1e2-4e08-bdcf-5a0923b787ba" 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_8955ba68-9414-4ded-8751-12ce1ed08902" 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_90da5a6d-a1e2-4e08-bdcf-5a0923b787ba" xlink:to="loc_us-gaap_AdvertisingExpense_8955ba68-9414-4ded-8751-12ce1ed08902" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_e2373d44-d1d1-4bf9-85db-53756ed5bd2c" 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_90da5a6d-a1e2-4e08-bdcf-5a0923b787ba" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_e2373d44-d1d1-4bf9-85db-53756ed5bd2c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0a44716f-afda-4b13-a1b3-ae4d36d9e6ac" 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_e2373d44-d1d1-4bf9-85db-53756ed5bd2c" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_0a44716f-afda-4b13-a1b3-ae4d36d9e6ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_0a44716f-afda-4b13-a1b3-ae4d36d9e6ac_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_0a44716f-afda-4b13-a1b3-ae4d36d9e6ac" xlink:to="loc_us-gaap_RelatedPartyDomain_0a44716f-afda-4b13-a1b3-ae4d36d9e6ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_ebcd4fb6-8fa5-4641-8dde-14e399437183" 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_0a44716f-afda-4b13-a1b3-ae4d36d9e6ac" xlink:to="loc_us-gaap_RelatedPartyDomain_ebcd4fb6-8fa5-4641-8dde-14e399437183" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_SummitHouseStudiosLLCMember_3f612b76-39ed-4d78-9f2d-15825ee36c91" xlink:href="hnst-20210331.xsd#hnst_SummitHouseStudiosLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_ebcd4fb6-8fa5-4641-8dde-14e399437183" xlink:to="loc_hnst_SummitHouseStudiosLLCMember_3f612b76-39ed-4d78-9f2d-15825ee36c91" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://honestco.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="hnst-20210331.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://honestco.com/role/SubsequentEventsDetails" xlink:type="extended" id="iea5199adeb1d4e5f851b7fafe2563e59_SubsequentEventsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_14ca72e8-b81c-47ac-b586-96e7c8d9d3aa" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_14ca72e8-b81c-47ac-b586-96e7c8d9d3aa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9a856b77-6a05-42af-a200-33899fda9369" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9a856b77-6a05-42af-a200-33899fda9369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2ee8bca1-3ce1-4b41-934a-2ac076c54b5a" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_2ee8bca1-3ce1-4b41-934a-2ac076c54b5a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DebtInstrumentInterestRateBase_0de4fd65-a800-4672-8d9a-c2701f46f78f" xlink:href="hnst-20210331.xsd#hnst_DebtInstrumentInterestRateBase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_hnst_DebtInstrumentInterestRateBase_0de4fd65-a800-4672-8d9a-c2701f46f78f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_DebtInstrumentCovenantLeverageRatioMaximum_be1e4bb6-1022-47a1-93e3-6e0cf907d44d" xlink:href="hnst-20210331.xsd#hnst_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_hnst_DebtInstrumentCovenantLeverageRatioMaximum_be1e4bb6-1022-47a1-93e3-6e0cf907d44d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToEmployees_daa643ee-964c-42e1-8394-7b446f129d8d" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_PaymentsToEmployees_daa643ee-964c-42e1-8394-7b446f129d8d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_158609e8-4354-42d3-b229-9df2963957f9" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_158609e8-4354-42d3-b229-9df2963957f9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod_eeae53bd-1991-4b19-9378-9e9c6441f137" xlink:href="hnst-20210331.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreasePeriod_eeae53bd-1991-4b19-9378-9e9c6441f137" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_d3f02260-80f0-4081-8c69-95f8979e9aa0" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_d3f02260-80f0-4081-8c69-95f8979e9aa0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_bf722975-f79c-4ce5-93d0-ba7e77b6f925" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_bf722975-f79c-4ce5-93d0-ba7e77b6f925" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_7a740ce0-463e-4958-9aae-0d9d9c369867" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_7a740ce0-463e-4958-9aae-0d9d9c369867" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_607f7fa6-3bf9-4980-8f5b-f516577bd614" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_607f7fa6-3bf9-4980-8f5b-f516577bd614" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfVestingInstallments_8402828c-048b-4acb-9a4a-b2e1c9c0709d" xlink:href="hnst-20210331.xsd#hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfVestingInstallments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_hnst_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfVestingInstallments_8402828c-048b-4acb-9a4a-b2e1c9c0709d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_e08e1c22-5ad8-4092-b1c0-b43b8043c0e5" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_e08e1c22-5ad8-4092-b1c0-b43b8043c0e5" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_6011c6e9-f214-4af6-a87d-578b9316a3ee" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_6011c6e9-f214-4af6-a87d-578b9316a3ee" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_24981e98-a2b4-464c-945c-31e871d7b3d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_24981e98-a2b4-464c-945c-31e871d7b3d2" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_b0b1f48f-8ac5-4c26-a3a7-c97d06854545" 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_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_b0b1f48f-8ac5-4c26-a3a7-c97d06854545" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_bef5e9a5-1f8c-4136-af73-13cf6b3f4d06" xlink:to="loc_us-gaap_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_b872c855-29c0-4d90-a1a3-a3b8a4786874" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_b872c855-29c0-4d90-a1a3-a3b8a4786874" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_b872c855-29c0-4d90-a1a3-a3b8a4786874_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_b872c855-29c0-4d90-a1a3-a3b8a4786874" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_b872c855-29c0-4d90-a1a3-a3b8a4786874_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_09920207-4a7b-4ca8-9ed5-a37a2a7afd06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_b872c855-29c0-4d90-a1a3-a3b8a4786874" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_09920207-4a7b-4ca8-9ed5-a37a2a7afd06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_d7848a1c-4bd4-4691-ab10-17c5016cb00e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_09920207-4a7b-4ca8-9ed5-a37a2a7afd06" xlink:to="loc_us-gaap_SubsequentEventMember_d7848a1c-4bd4-4691-ab10-17c5016cb00e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_624a41f6-227e-4794-b821-0e1d1b619cf9" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_624a41f6-227e-4794-b821-0e1d1b619cf9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_624a41f6-227e-4794-b821-0e1d1b619cf9_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_624a41f6-227e-4794-b821-0e1d1b619cf9" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_624a41f6-227e-4794-b821-0e1d1b619cf9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_48c225df-105d-4988-9c8e-1e8081770a8a" 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_624a41f6-227e-4794-b821-0e1d1b619cf9" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_48c225df-105d-4988-9c8e-1e8081770a8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_JPMorganChaseBankMember_a7e06fe0-55f5-42f4-b4a5-c54f34c078e7" xlink:href="hnst-20210331.xsd#hnst_JPMorganChaseBankMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_48c225df-105d-4988-9c8e-1e8081770a8a" xlink:to="loc_hnst_JPMorganChaseBankMember_a7e06fe0-55f5-42f4-b4a5-c54f34c078e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_d45bfc64-ca1e-4326-8f16-fccca850b9b2" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_DebtInstrumentAxis_d45bfc64-ca1e-4326-8f16-fccca850b9b2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d45bfc64-ca1e-4326-8f16-fccca850b9b2_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_d45bfc64-ca1e-4326-8f16-fccca850b9b2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d45bfc64-ca1e-4326-8f16-fccca850b9b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5f7ce62f-66af-45d4-9b94-0eab5f6e84af" 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_d45bfc64-ca1e-4326-8f16-fccca850b9b2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5f7ce62f-66af-45d4-9b94-0eab5f6e84af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021CreditFacilityMember_748981e4-ec67-4702-9efb-323ba4150333" xlink:href="hnst-20210331.xsd#hnst_A2021CreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5f7ce62f-66af-45d4-9b94-0eab5f6e84af" xlink:to="loc_hnst_A2021CreditFacilityMember_748981e4-ec67-4702-9efb-323ba4150333" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_37750877-82bd-4780-ad66-a9b29d5881a7" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_CreditFacilityAxis_37750877-82bd-4780-ad66-a9b29d5881a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_37750877-82bd-4780-ad66-a9b29d5881a7_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_37750877-82bd-4780-ad66-a9b29d5881a7" xlink:to="loc_us-gaap_CreditFacilityDomain_37750877-82bd-4780-ad66-a9b29d5881a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_9e97597f-8e4d-443c-afa1-9cf1364d8a94" 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_37750877-82bd-4780-ad66-a9b29d5881a7" xlink:to="loc_us-gaap_CreditFacilityDomain_9e97597f-8e4d-443c-afa1-9cf1364d8a94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_c03e05ee-d4e3-4d68-996b-976717af44e3" 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_9e97597f-8e4d-443c-afa1-9cf1364d8a94" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_c03e05ee-d4e3-4d68-996b-976717af44e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_1578788c-883c-4fbf-b37b-b9bd44b6ba7a" 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_9e97597f-8e4d-443c-afa1-9cf1364d8a94" xlink:to="loc_us-gaap_LetterOfCreditMember_1578788c-883c-4fbf-b37b-b9bd44b6ba7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_f60400d5-b818-4a7f-986a-72557f242c9f" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_VariableRateAxis_f60400d5-b818-4a7f-986a-72557f242c9f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_f60400d5-b818-4a7f-986a-72557f242c9f_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_f60400d5-b818-4a7f-986a-72557f242c9f" xlink:to="loc_us-gaap_VariableRateDomain_f60400d5-b818-4a7f-986a-72557f242c9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_3ca57508-8c54-4a11-b5bb-a63c78f5773b" 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_f60400d5-b818-4a7f-986a-72557f242c9f" xlink:to="loc_us-gaap_VariableRateDomain_3ca57508-8c54-4a11-b5bb-a63c78f5773b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_88ad0fed-843d-4df3-91ae-6557d22b9af6" 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_3ca57508-8c54-4a11-b5bb-a63c78f5773b" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_88ad0fed-843d-4df3-91ae-6557d22b9af6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_24263532-41a9-4725-ac3d-ce8c6db1bba6" 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_3ca57508-8c54-4a11-b5bb-a63c78f5773b" xlink:to="loc_us-gaap_BaseRateMember_24263532-41a9-4725-ac3d-ce8c6db1bba6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_876d80e7-f2ff-4662-af4e-744705211077" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_srt_RangeAxis_876d80e7-f2ff-4662-af4e-744705211077" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_876d80e7-f2ff-4662-af4e-744705211077_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_876d80e7-f2ff-4662-af4e-744705211077" xlink:to="loc_srt_RangeMember_876d80e7-f2ff-4662-af4e-744705211077_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ae56f52b-9e3a-465a-ae1f-768accff3e29" 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_876d80e7-f2ff-4662-af4e-744705211077" xlink:to="loc_srt_RangeMember_ae56f52b-9e3a-465a-ae1f-768accff3e29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_3910d46a-391d-4042-ac86-16e2fc71a371" 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_ae56f52b-9e3a-465a-ae1f-768accff3e29" xlink:to="loc_srt_MinimumMember_3910d46a-391d-4042-ac86-16e2fc71a371" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0565d861-e507-4a97-b381-e5db11133dab" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_AwardTypeAxis_0565d861-e507-4a97-b381-e5db11133dab" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0565d861-e507-4a97-b381-e5db11133dab_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_0565d861-e507-4a97-b381-e5db11133dab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0565d861-e507-4a97-b381-e5db11133dab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_53f89786-4607-42d0-8eb7-71e933df8251" 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_0565d861-e507-4a97-b381-e5db11133dab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_53f89786-4607-42d0-8eb7-71e933df8251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_f002c3dd-abfd-482f-bb65-a7f18a25ca24" 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_53f89786-4607-42d0-8eb7-71e933df8251" xlink:to="loc_us-gaap_EmployeeStockMember_f002c3dd-abfd-482f-bb65-a7f18a25ca24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_40d1adb3-5342-4f05-bd0b-3b501a085d3c" 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_53f89786-4607-42d0-8eb7-71e933df8251" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_40d1adb3-5342-4f05-bd0b-3b501a085d3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_23f9cf8d-fcce-43a4-a02f-c8aac3ed9565" 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_SubsequentEventTable_f7cae5e9-c10d-4b77-a423-7b87719bcab0" xlink:to="loc_us-gaap_PlanNameAxis_23f9cf8d-fcce-43a4-a02f-c8aac3ed9565" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_23f9cf8d-fcce-43a4-a02f-c8aac3ed9565_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_23f9cf8d-fcce-43a4-a02f-c8aac3ed9565" xlink:to="loc_us-gaap_PlanNameDomain_23f9cf8d-fcce-43a4-a02f-c8aac3ed9565_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" 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_23f9cf8d-fcce-43a4-a02f-c8aac3ed9565" xlink:to="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021EquityIncentivePlanMember_98aaa82a-044d-4876-9a5a-c07c8a393cb1" xlink:href="hnst-20210331.xsd#hnst_A2021EquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" xlink:to="loc_hnst_A2021EquityIncentivePlanMember_98aaa82a-044d-4876-9a5a-c07c8a393cb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021EquityIncentivePlanNewSharesMember_60df49d4-bc29-4a4a-9d5a-bc1e0b4912b5" xlink:href="hnst-20210331.xsd#hnst_A2021EquityIncentivePlanNewSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" xlink:to="loc_hnst_A2021EquityIncentivePlanNewSharesMember_60df49d4-bc29-4a4a-9d5a-bc1e0b4912b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2011StockIncentivePlanAdditionalSharesMember_c9f5c689-32cb-48e7-8c22-7eb6a170718a" xlink:href="hnst-20210331.xsd#hnst_A2011StockIncentivePlanAdditionalSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" xlink:to="loc_hnst_A2011StockIncentivePlanAdditionalSharesMember_c9f5c689-32cb-48e7-8c22-7eb6a170718a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021EmployeeStockPurchasePlanMember_5a4819e8-d7c8-4ebe-816f-79d5bd88c099" xlink:href="hnst-20210331.xsd#hnst_A2021EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" xlink:to="loc_hnst_A2021EmployeeStockPurchasePlanMember_5a4819e8-d7c8-4ebe-816f-79d5bd88c099" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hnst_A2021PlanIPOAwardsMember_0b238a59-98a5-4da1-b3de-bd035f8cedbc" xlink:href="hnst-20210331.xsd#hnst_A2021PlanIPOAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b5840663-fb65-45a8-a9bd-f81e93879615" xlink:to="loc_hnst_A2021PlanIPOAwardsMember_0b238a59-98a5-4da1-b3de-bd035f8cedbc" xlink:type="arc" order="4"/>
  </link:definitionLink>
</link:linkbase>
