diff --git a/airflow-core/src/airflow/api_fastapi/execution_api/routes/dag_runs.py b/airflow-core/src/airflow/api_fastapi/execution_api/routes/dag_runs.py
index 448d0b6945abf..084dbae8b380f 100644
--- a/airflow-core/src/airflow/api_fastapi/execution_api/routes/dag_runs.py
+++ b/airflow-core/src/airflow/api_fastapi/execution_api/routes/dag_runs.py
@@ -32,9 +32,12 @@
 from airflow.api_fastapi.compat import HTTP_422_UNPROCESSABLE_CONTENT
 from airflow.api_fastapi.execution_api.datamodels.dagrun import DagRunStateResponse, TriggerDAGRunPayload
 from airflow.api_fastapi.execution_api.datamodels.taskinstance import DagRun
+from airflow.api_fastapi.execution_api.datamodels.token import TIToken
+from airflow.api_fastapi.execution_api.security import CurrentTIToken
 from airflow.exceptions import DagRunAlreadyExists
 from airflow.models.dag import DagModel
 from airflow.models.dagrun import DagRun as DagRunModel
+from airflow.models.taskinstance import TaskInstance
 from airflow.utils.state import DagRunState
 from airflow.utils.types import DagRunTriggeredByType, DagRunType
 
@@ -94,6 +97,7 @@ def trigger_dag_run(
     run_id: str,
     payload: TriggerDAGRunPayload,
     session: SessionDep,
+    token: TIToken = CurrentTIToken,
 ) -> None:
     """Trigger a Dag run."""
     dm = session.scalar(select(DagModel).where(~DagModel.is_stale, DagModel.dag_id == dag_id).limit(1))
@@ -121,6 +125,11 @@ def trigger_dag_run(
             },
         )
 
+    # Inherit triggering_user_name from the calling task's DagRun so chains of
+    # TriggerDagRunOperator preserve the original human user across child runs.
+    parent_ti = session.get(TaskInstance, token.id)
+    triggering_user_name = parent_ti.dag_run.triggering_user_name if parent_ti else None
+
     try:
         trigger_dag(
             dag_id=dag_id,
@@ -129,6 +138,7 @@ def trigger_dag_run(
             conf=payload.conf,
             logical_date=payload.logical_date,
             triggered_by=DagRunTriggeredByType.OPERATOR,
+            triggering_user_name=triggering_user_name,
             replace_microseconds=False,
             partition_key=payload.partition_key,
             note=payload.note,
diff --git a/airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_dag_runs.py b/airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_dag_runs.py
index b84b993f1d63d..337bc1c90b8d5 100644
--- a/airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_dag_runs.py
+++ b/airflow-core/tests/unit/api_fastapi/execution_api/versions/head/test_dag_runs.py
@@ -19,9 +19,12 @@
 
 import pytest
 import time_machine
+from fastapi import Request
 from sqlalchemy import select, update
 
 from airflow._shared.timezones import timezone
+from airflow.api_fastapi.execution_api.datamodels.token import TIClaims, TIToken
+from airflow.api_fastapi.execution_api.security import require_auth
 from airflow.models import DagModel
 from airflow.models.dagrun import DagRun
 from airflow.providers.standard.operators.empty import EmptyOperator
@@ -219,6 +222,44 @@ def test_trigger_dag_run_already_exists(self, client, session, dag_maker):
             }
         }
 
+    @pytest.mark.parametrize("parent_triggering_user_name", ["alice", None])
+    def test_trigger_dag_run_inherits_triggering_user_name(
+        self, client, exec_app, session, dag_maker, parent_triggering_user_name
+    ):
+        """Child DAG run inherits triggering_user_name from the calling task's parent run."""
+        parent_dag_id = "parent_dag_inherits"
+        parent_run_id = "parent_run"
+        child_dag_id = "child_dag_inherits"
+        child_run_id = "child_run"
+        logical_date = timezone.datetime(2025, 2, 20)
+
+        with dag_maker(dag_id=parent_dag_id, session=session, serialized=True):
+            EmptyOperator(task_id="trigger_task")
+        parent_run = dag_maker.create_dagrun(
+            run_id=parent_run_id, triggering_user_name=parent_triggering_user_name
+        )
+        parent_ti = parent_run.task_instances[0]
+
+        with dag_maker(dag_id=child_dag_id, session=session, serialized=True):
+            EmptyOperator(task_id="child_task")
+        session.commit()
+
+        async def auth_as_parent_ti(request: Request) -> TIToken:
+            return TIToken(id=parent_ti.id, claims=TIClaims(scope="execution"))
+
+        exec_app.dependency_overrides[require_auth] = auth_as_parent_ti
+        try:
+            response = client.post(
+                f"/execution/dag-runs/{child_dag_id}/{child_run_id}",
+                json={"logical_date": logical_date.isoformat()},
+            )
+        finally:
+            exec_app.dependency_overrides.pop(require_auth, None)
+
+        assert response.status_code == 204
+        child_run = session.scalars(select(DagRun).where(DagRun.run_id == child_run_id)).one()
+        assert child_run.triggering_user_name == parent_triggering_user_name
+
 
 class TestDagRunClear:
     def setup_method(self):