diff --git a/airflow-core/src/airflow/models/taskinstance.py b/airflow-core/src/airflow/models/taskinstance.py
index 8b690b417e1ef..a3dbd5608e548 100644
--- a/airflow-core/src/airflow/models/taskinstance.py
+++ b/airflow-core/src/airflow/models/taskinstance.py
@@ -617,6 +617,8 @@ def log_url(self) -> str:
         """Log URL for TaskInstance."""
         run_id = quote(self.run_id)
         base_url = conf.get("api", "base_url", fallback="http://localhost:8080/")
+        if not base_url.endswith('/'):
+            base_url += '/'
         map_index = f"/mapped/{self.map_index}" if self.map_index >= 0 else ""
         try_number = f"?try_number={self.try_number}" if self.try_number > 0 else ""
         _log_uri = f"{base_url}dags/{self.dag_id}/runs/{run_id}/tasks/{self.task_id}{map_index}{try_number}"
diff --git a/airflow-core/tests/unit/models/test_taskinstance.py b/airflow-core/tests/unit/models/test_taskinstance.py
index f5bf36bcf4e0e..e93943ef01f09 100644
--- a/airflow-core/tests/unit/models/test_taskinstance.py
+++ b/airflow-core/tests/unit/models/test_taskinstance.py
@@ -89,6 +89,7 @@
 from tests_common.test_utils import db
 from tests_common.test_utils.db import clear_db_connections, clear_db_runs
 from tests_common.test_utils.mock_operators import MockOperator
+from tests_common.test_utils.config import conf_vars
 from unit.models import DEFAULT_DATE
 
 pytestmark = [pytest.mark.db_test]
@@ -1558,6 +1559,11 @@ def test_log_url(self, create_task_instance):
         expected_url = "http://localhost:8080/dags/my_dag/runs/test/tasks/op"
         assert ti.log_url == expected_url
 
+        # Test with base_url that doesn't end with a slash
+        with conf_vars({('api', 'base_url'): 'http://example.com'}):
+            expected_url = "http://example.com/dags/my_dag/runs/test/tasks/op"
+            assert ti.log_url == expected_url
+
         ti.map_index = 1
         ti.try_number = 2
         session = settings.Session()