diff --git a/lms/services/roster.py b/lms/services/roster.py
index 8194822ec6..71164cb6e2 100644
--- a/lms/services/roster.py
+++ b/lms/services/roster.py
@@ -1,6 +1,6 @@
 from logging import getLogger
 
-from sqlalchemy import Select, select, update
+from sqlalchemy import Select, func, select, text, update
 
 from lms.models import (
     ApplicationInstance,
@@ -251,6 +251,11 @@ def _get_roster_users(self, roster, tool_consumer_instance_guid):
         for member in roster:
             lti_user_id = member.get("lti11_legacy_user_id") or member["user_id"]
             lti_v13_user_id = member["user_id"]
+            lms_api_user_id = (
+                member.get("message", [{}])[0]
+                .get("https://purl.imsglobal.org/spec/lti/claim/custom", {})
+                .get("canvas_user_id")
+            )
             name = display_name(
                 given_name=member.get("name", ""),
                 family_name=member.get("family_name", ""),
@@ -270,6 +275,7 @@ def _get_roster_users(self, roster, tool_consumer_instance_guid):
                     "lti_v13_user_id": lti_v13_user_id,
                     "h_userid": h_userid,
                     "display_name": name,
+                    "lms_api_user_id": lms_api_user_id,
                 }
             )
 
@@ -282,6 +288,14 @@ def _get_roster_users(self, roster, tool_consumer_instance_guid):
                 "updated",
                 # lti_v13_user_id is not going to change but we want to backfill it for existing users.
                 "lti_v13_user_id",
+                # Same for lms_api_user_id, not going to change for existing user but we are backfilling for now
+                (
+                    "lms_api_user_id",
+                    func.coalesce(
+                        text('"excluded"."lms_api_user_id"'),
+                        text('"lms_user"."lms_api_user_id"'),
+                    ),
+                ),
             ],
         )
 
diff --git a/tests/unit/lms/services/roster_test.py b/tests/unit/lms/services/roster_test.py
index f53ffd5c65..ee54a6d0e2 100644
--- a/tests/unit/lms/services/roster_test.py
+++ b/tests/unit/lms/services/roster_test.py
@@ -218,6 +218,39 @@ def test_fetch_assignment_roster(
         assert roster[3].lms_user.lti_user_id == "USER_ID_INACTIVE"
         assert not roster[3].active
 
+    def test_fetch_assignment_roster_with_canvas_user_id(
+        self, svc, lti_names_roles_service, db_session, lti_role_service, assignment
+    ):
+        lti_names_roles_service.get_context_memberships.return_value = [
+            {
+                "user_id": "USER_ID",
+                "roles": ["ROLE1"],
+                "status": "Active",
+                "message": [
+                    {
+                        "https://purl.imsglobal.org/spec/lti/claim/custom": {
+                            "canvas_user_id": "API_ID"
+                        }
+                    }
+                ],
+            },
+        ]
+        lti_role_service.get_roles.return_value = [
+            factories.LTIRole(value="ROLE1"),
+        ]
+
+        svc.fetch_assignment_roster(assignment)
+
+        roster = db_session.scalars(
+            select(AssignmentRoster)
+            .order_by(AssignmentRoster.lms_user_id)
+            .where(AssignmentRoster.assignment_id == assignment.id)
+        ).all()
+
+        assert roster[0].assignment_id == assignment.id
+        assert roster[0].lms_user.lti_user_id == "USER_ID"
+        assert roster[0].lms_user.lms_api_user_id == "API_ID"
+
     @pytest.mark.parametrize(
         "known_error",
         [