diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index b6dd1c27fee169..bf32ff6dd3cd9c 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -3102,6 +3102,10 @@ def _mock_call(self, *args, **kwargs):
 
         return ret_value
 
+    def _increment_mock_call(self, /, *args, **kwargs):
+        with self._mock_calls_events_lock:
+            super()._increment_mock_call(*args, **kwargs)
+
     def wait_until_called(self, *, timeout=_timeout_unset):
         """Wait until the mock object is called.
 
diff --git a/Misc/NEWS.d/next/Library/2026-05-21-11-25-58.gh-issue-150175.8H4Caz.rst b/Misc/NEWS.d/next/Library/2026-05-21-11-25-58.gh-issue-150175.8H4Caz.rst
new file mode 100644
index 00000000000000..80fc80d4d50a63
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-05-21-11-25-58.gh-issue-150175.8H4Caz.rst
@@ -0,0 +1,3 @@
+Fix race condition in :class:`unittest.mock.ThreadingMock` where
+concurrent calls could lose increments to ``call_count`` and other
+attributes due to a missing lock in ``_increment_mock_call``.