diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index f940235a6e50dcb..4e0f9ad42defaff 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -597,7 +597,7 @@ def __set_return_value(self, value):
 
     __return_value_doc = "The value to be returned when the mock is called."
     return_value = property(__get_return_value, __set_return_value,
-                            __return_value_doc)
+                            doc=__return_value_doc)
 
 
     @property
diff --git a/Misc/NEWS.d/next/Library/2026-09-05-15-27-11.gh-issue-156970.DxlgbB.rst b/Misc/NEWS.d/next/Library/2026-09-05-15-27-11.gh-issue-156970.DxlgbB.rst
new file mode 100644
index 000000000000000..dd60841efe821c2
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-09-05-15-27-11.gh-issue-156970.DxlgbB.rst
@@ -0,0 +1 @@
+Set the docstring of :attr:`unittest.mock.Mock.return_value`.