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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f3fdd-d141-7532-bb10-3e11e4ad3424,g:1ddd3362-16ba-4fab-b072-5c2e80ef0aca-->
<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://tarsusrx.com/role/Cover" xlink:type="simple" xlink:href="tars-20260706.xsd#Cover"/>
  <link:definitionLink xlink:role="http://tarsusrx.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_019f3fdd-d141-7cd3-8de2-5806180bda65" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_DocumentInformationTable_019f3fdd-d141-7cd3-8de2-5806180bda65" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesAddressTypeAxis_019f3fdd-d141-7630-9af8-df27dfb347ba" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressesAddressTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_019f3fdd-d141-7cd3-8de2-5806180bda65" xlink:to="loc_dei_EntityAddressesAddressTypeAxis_019f3fdd-d141-7630-9af8-df27dfb347ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019f3fdd-d141-7630-9af8-df27dfb347ba_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019f3fdd-d141-7630-9af8-df27dfb347ba" xlink:to="loc_dei_AddressTypeDomain_019f3fdd-d141-7630-9af8-df27dfb347ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019f3fdd-d141-74af-8a21-5e31da9056f4" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019f3fdd-d141-7630-9af8-df27dfb347ba" xlink:to="loc_dei_AddressTypeDomain_019f3fdd-d141-74af-8a21-5e31da9056f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_FormerAddressMember_019f3fdd-d141-7109-bf72-02be1be7fe78" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_FormerAddressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_AddressTypeDomain_019f3fdd-d141-74af-8a21-5e31da9056f4" xlink:to="loc_dei_FormerAddressMember_019f3fdd-d141-7109-bf72-02be1be7fe78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019f3fdd-d141-7dad-8b82-5ca700e9abb3" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_DocumentType_019f3fdd-d141-7dad-8b82-5ca700e9abb3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019f3fdd-d141-7124-a4a3-e886b7526545" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_DocumentPeriodEndDate_019f3fdd-d141-7124-a4a3-e886b7526545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019f3fdd-d141-78f1-8e47-7a3bcd3fff15" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityRegistrantName_019f3fdd-d141-78f1-8e47-7a3bcd3fff15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019f3fdd-d141-77ac-9bc4-eda00906534d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019f3fdd-d141-77ac-9bc4-eda00906534d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019f3fdd-d141-7667-afc9-cd525d48bf05" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityFileNumber_019f3fdd-d141-7667-afc9-cd525d48bf05" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019f3fdd-d141-7ffe-b793-07713d3aab29" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityTaxIdentificationNumber_019f3fdd-d141-7ffe-b793-07713d3aab29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019f3fdd-d141-787a-bb8f-911d007f5051" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityAddressAddressLine1_019f3fdd-d141-787a-bb8f-911d007f5051" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_019f3fdd-d141-7a9d-88ab-0cc4d1c711e1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityAddressAddressLine2_019f3fdd-d141-7a9d-88ab-0cc4d1c711e1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019f3fdd-d141-7de4-a8e1-98816bc01e24" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityAddressCityOrTown_019f3fdd-d141-7de4-a8e1-98816bc01e24" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019f3fdd-d141-7217-a7cb-fa3b0228d165" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityAddressStateOrProvince_019f3fdd-d141-7217-a7cb-fa3b0228d165" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019f3fdd-d141-77df-aa17-d8641bda6c43" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityAddressPostalZipCode_019f3fdd-d141-77df-aa17-d8641bda6c43" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019f3fdd-d141-72f6-90d8-40cc3085399a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_CityAreaCode_019f3fdd-d141-72f6-90d8-40cc3085399a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019f3fdd-d141-7f46-9f6f-5bdaafc2dbf4" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_LocalPhoneNumber_019f3fdd-d141-7f46-9f6f-5bdaafc2dbf4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_019f3fdd-d141-7172-b813-8eeb45be8c4e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_WrittenCommunications_019f3fdd-d141-7172-b813-8eeb45be8c4e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_019f3fdd-d141-7a8c-a72e-7a22643622eb" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_SolicitingMaterial_019f3fdd-d141-7a8c-a72e-7a22643622eb" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_019f3fdd-d141-73e9-914c-adc0737caedf" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_PreCommencementTenderOffer_019f3fdd-d141-73e9-914c-adc0737caedf" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_019f3fdd-d141-738b-a145-8eff367586e7" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_019f3fdd-d141-738b-a145-8eff367586e7" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019f3fdd-d141-7cbc-a050-66146fe4bd93" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_Security12bTitle_019f3fdd-d141-7cbc-a050-66146fe4bd93" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019f3fdd-d141-788f-a2b2-8287c0916738" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_TradingSymbol_019f3fdd-d141-788f-a2b2-8287c0916738" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019f3fdd-d141-73d2-a55a-8c90c2a29075" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_SecurityExchangeName_019f3fdd-d141-73d2-a55a-8c90c2a29075" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019f3fdd-d141-729e-8167-df981a3aa14e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityEmergingGrowthCompany_019f3fdd-d141-729e-8167-df981a3aa14e" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019f3fdd-d141-7e1d-9a60-ffdb9d983c0f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_EntityCentralIndexKey_019f3fdd-d141-7e1d-9a60-ffdb9d983c0f" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019f3fdd-d141-7c57-89a9-328a4e00df45" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3fdd-d141-767b-bf5a-cbca6e854803" xlink:to="loc_dei_AmendmentFlag_019f3fdd-d141-7c57-89a9-328a4e00df45" xlink:type="arc" order="22"/>
  </link:definitionLink>
</link:linkbase>
