diff --git a/stdlib/argparse.pyi b/stdlib/argparse.pyi
index ef043661150c..ae99eb0368ea 100644
--- a/stdlib/argparse.pyi
+++ b/stdlib/argparse.pyi
@@ -91,15 +91,40 @@ class _ActionsContainer:
         version: str = ...,
         **kwargs: Any,
     ) -> Action: ...
-    def add_argument_group(
-        self,
-        title: str | None = None,
-        description: str | None = None,
-        *,
-        prefix_chars: str = ...,
-        argument_default: Any = ...,
-        conflict_handler: str = ...,
-    ) -> _ArgumentGroup: ...
+    if sys.version_info >= (3, 14):
+        @overload
+        def add_argument_group(
+            self,
+            title: str | None = None,
+            description: str | None = None,
+            *,
+            # argument_default's type must be valid for the arguments in the group
+            argument_default: Any = ...,
+            conflict_handler: str = ...,
+        ) -> _ArgumentGroup: ...
+        @overload
+        @deprecated("The `prefix_chars` parameter deprecated since Python 3.14.")
+        def add_argument_group(
+            self,
+            title: str | None = None,
+            description: str | None = None,
+            *,
+            prefix_chars: str,
+            argument_default: Any = ...,
+            conflict_handler: str = ...,
+        ) -> _ArgumentGroup: ...
+    else:
+        def add_argument_group(
+            self,
+            title: str | None = None,
+            description: str | None = None,
+            *,
+            prefix_chars: str = ...,
+            # argument_default's type must be valid for the arguments in the group
+            argument_default: Any = ...,
+            conflict_handler: str = ...,
+        ) -> _ArgumentGroup: ...
+
     def add_mutually_exclusive_group(self, *, required: bool = False) -> _MutuallyExclusiveGroup: ...
     def _add_action(self, action: _ActionT) -> _ActionT: ...
     def _remove_action(self, action: Action) -> None: ...