diff --git a/airflow/sensors/external_task.py b/airflow/sensors/external_task.py
index 959ebe5131bd3..69ba41ef09354 100644
--- a/airflow/sensors/external_task.py
+++ b/airflow/sensors/external_task.py
@@ -366,11 +366,14 @@ def get_count(self, dttm_filter, session, states) -> int:
             ) / len(self.external_task_ids)
         elif self.external_task_group_id:
             external_task_group_task_ids = self.get_external_task_group_task_ids(session, dttm_filter)
-            count = (
-                self._count_query(TI, session, states, dttm_filter)
-                .filter(tuple_in_condition((TI.task_id, TI.map_index), external_task_group_task_ids))
-                .scalar()
-            ) / len(external_task_group_task_ids)
+            if not external_task_group_task_ids:
+                count = 0
+            else:
+                count = (
+                    self._count_query(TI, session, states, dttm_filter)
+                    .filter(tuple_in_condition((TI.task_id, TI.map_index), external_task_group_task_ids))
+                    .scalar()
+                ) / len(external_task_group_task_ids)
         else:
             count = self._count_query(DR, session, states, dttm_filter).scalar()
         return count
diff --git a/tests/sensors/test_external_task_sensor.py b/tests/sensors/test_external_task_sensor.py
index 616c9c5cabbcc..a5259084b13f6 100644
--- a/tests/sensors/test_external_task_sensor.py
+++ b/tests/sensors/test_external_task_sensor.py
@@ -808,6 +808,26 @@ def test_external_task_group_with_mapped_tasks_failed_states(self):
         ):
             op.run(start_date=DEFAULT_DATE, end_date=DEFAULT_DATE, ignore_ti_state=True)
 
+    def test_external_task_group_when_there_is_no_TIs(self):
+        """Test that the sensor does not fail when there are no TIs to check."""
+        self.add_time_sensor()
+        self.add_dummy_task_group_with_dynamic_tasks(State.FAILED)
+        op = ExternalTaskSensor(
+            task_id="test_external_task_sensor_check",
+            external_dag_id=TEST_DAG_ID,
+            external_task_group_id=TEST_TASK_GROUP_ID,
+            failed_states=[State.FAILED],
+            dag=self.dag,
+            poke_interval=1,
+            timeout=3,
+        )
+        with pytest.raises(AirflowSensorTimeout):
+            op.run(
+                start_date=DEFAULT_DATE + timedelta(hours=1),
+                end_date=DEFAULT_DATE + timedelta(hours=1),
+                ignore_ti_state=True,
+            )
+
 
 def test_external_task_sensor_check_zipped_dag_existence(dag_zip_maker):
     with dag_zip_maker("test_external_task_sensor_check_existense.py") as dagbag: