diff --git a/src/flask/templating.py b/src/flask/templating.py
index bb3e7fd5dd..b39adb77ea 100644
--- a/src/flask/templating.py
+++ b/src/flask/templating.py
@@ -131,7 +131,8 @@ def _render(template: Template, context: dict, app: "Flask") -> str:
 
 
 def render_template(
-    template_name_or_list: t.Union[str, t.List[str]], **context: t.Any
+    template_name_or_list: t.Union[str, Template, t.List[t.Union[str, Template]]],
+    **context: t.Any
 ) -> str:
     """Renders a template from the template folder with the given
     context.