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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f3d39-753e-7ca2-9cc4-3ab2102225e5,g:81d57409-ac8c-4076-8119-f7b1098c5deb-->
<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://www.forwardair.com/role/CoverPage" xlink:type="simple" xlink:href="fwrd-20260710.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://www.forwardair.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_019f3d39-753e-7ff1-b65c-fc49eecc0a39" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:to="loc_dei_DocumentInformationTable_019f3d39-753e-7ff1-b65c-fc49eecc0a39" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressesAddressTypeAxis_019f3d39-753e-7be3-a7a5-a06fa642313f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressesAddressTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_019f3d39-753e-7ff1-b65c-fc49eecc0a39" xlink:to="loc_dei_EntityAddressesAddressTypeAxis_019f3d39-753e-7be3-a7a5-a06fa642313f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019f3d39-753e-7be3-a7a5-a06fa642313f_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019f3d39-753e-7be3-a7a5-a06fa642313f" xlink:to="loc_dei_AddressTypeDomain_019f3d39-753e-7be3-a7a5-a06fa642313f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AddressTypeDomain_019f3d39-753e-794f-8436-1f448da69d72" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AddressTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_EntityAddressesAddressTypeAxis_019f3d39-753e-7be3-a7a5-a06fa642313f" xlink:to="loc_dei_AddressTypeDomain_019f3d39-753e-794f-8436-1f448da69d72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_FormerAddressMember_019f3d39-753e-731f-b276-679f5fd02c36" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_FormerAddressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_AddressTypeDomain_019f3d39-753e-794f-8436-1f448da69d72" xlink:to="loc_dei_FormerAddressMember_019f3d39-753e-731f-b276-679f5fd02c36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019f3d39-753e-7837-a98f-38799432a03e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:to="loc_dei_EntityAddressAddressLine1_019f3d39-753e-7837-a98f-38799432a03e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_019f3d39-753e-737a-8e9d-f5d1ad62a99d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:to="loc_dei_EntityAddressAddressLine2_019f3d39-753e-737a-8e9d-f5d1ad62a99d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019f3d39-753e-7cda-9263-1569a0bb2f0f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:to="loc_dei_EntityAddressCityOrTown_019f3d39-753e-7cda-9263-1569a0bb2f0f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019f3d39-753e-7ed9-b63f-eb36e9f7feb2" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:to="loc_dei_EntityAddressStateOrProvince_019f3d39-753e-7ed9-b63f-eb36e9f7feb2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019f3d39-753e-7f76-bc6f-eb6167a1f7cc" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_019f3d39-753e-73d4-a055-efc618326e61" xlink:to="loc_dei_EntityAddressPostalZipCode_019f3d39-753e-7f76-bc6f-eb6167a1f7cc" xlink:type="arc" order="4"/>
  </link:definitionLink>
</link:linkbase>
