diff --git a/providers/fab/src/airflow/providers/fab/auth_manager/models/__init__.py b/providers/fab/src/airflow/providers/fab/auth_manager/models/__init__.py
index cb6f59f6ad576..dd895e1c0b736 100644
--- a/providers/fab/src/airflow/providers/fab/auth_manager/models/__init__.py
+++ b/providers/fab/src/airflow/providers/fab/auth_manager/models/__init__.py
@@ -288,8 +288,8 @@ def perms(self):
                 }
         return self._perms
 
-    def get_id(self):
-        return self.id
+    def get_id(self) -> str:
+        return str(self.id)
 
     def get_name(self) -> str:
         return self.username or self.email or self.user_id
diff --git a/providers/fab/tests/unit/fab/auth_manager/models/test_user_model.py b/providers/fab/tests/unit/fab/auth_manager/models/test_user_model.py
new file mode 100644
index 0000000000000..051e39cd0530d
--- /dev/null
+++ b/providers/fab/tests/unit/fab/auth_manager/models/test_user_model.py
@@ -0,0 +1,41 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+import pytest
+
+from airflow.providers.fab.auth_manager.models import User
+
+pytestmark = pytest.mark.db_test
+
+
+@pytest.mark.parametrize(
+    "user_id, expected_id",
+    [
+        (999, "999"),
+        ("999", "999"),
+    ],
+)
+def test_get_id_returns_str(user_id: int | str, expected_id: str) -> None:
+    """
+    Ensure get_id() always returns a string representation of the id.
+    """
+    user = User()
+    user.id = user_id
+    result = user.get_id()
+    assert isinstance(result, str), f"Expected str, got {type(result)}"
+    assert result == expected_id