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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:01a09c13-852b-7a48-926d-76307c09f883,g:4076af71-650d-4ee4-bac4-356bfcd075a5-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:goss="http://www.gossamerbio.com/20260916" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.gossamerbio.com/20260916">
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei-sub/2026" schemaLocation="https://xbrl.sec.gov/dei/2026/dei-sub-2026.xsd"/>
  <xs:annotation>
    <xs:appinfo/>
  </xs:annotation>
</xs:schema>