diff --git a/doc/api/next_api_changes/deprecations/23166-ES.rst b/doc/api/next_api_changes/deprecations/23166-ES.rst
new file mode 100644
index 000000000000..cfc362ec306c
--- /dev/null
+++ b/doc/api/next_api_changes/deprecations/23166-ES.rst
@@ -0,0 +1,5 @@
+``Legend`` constructor
+~~~~~~~~~~~~~~~~~~~~~~
+
+All arguments to `.legend.Legend` other than *parent*, *handles*, and *labels*
+will become keyword-only in a future version.
diff --git a/lib/matplotlib/legend.py b/lib/matplotlib/legend.py
index 7aef9ed7e8b3..27069efaffb0 100644
--- a/lib/matplotlib/legend.py
+++ b/lib/matplotlib/legend.py
@@ -294,6 +294,7 @@ class Legend(Artist):
     def __str__(self):
         return "Legend"
 
+    @_api.make_keyword_only("3.6", "loc")
     @_docstring.dedent_interpd
     def __init__(
         self, parent, handles, labels,