diff --git a/doc/api/next_api_changes/deprecations/20237-TH.rst b/doc/api/next_api_changes/deprecations/20237-TH.rst
index 2120fb9b9bef..435986f94f0f 100644
--- a/doc/api/next_api_changes/deprecations/20237-TH.rst
+++ b/doc/api/next_api_changes/deprecations/20237-TH.rst
@@ -3,11 +3,11 @@ QuadMesh signature
 The ``QuadMesh`` signature ::
 
     def __init__(meshWidth, meshHeight, coordinates,
-                 antialiased=True, shading=False, **kwargs)
+                 antialiased=True, shading='flat', **kwargs)
 
 is deprecated and replaced by the new signature ::
 
-    def __init__(coordinates, *, antialiased=True, shading=False, **kwargs)
+    def __init__(coordinates, *, antialiased=True, shading='flat', **kwargs)
 
 In particular:
 
diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
index 1f88bbef3e4f..ee9058e9f52a 100644
--- a/lib/matplotlib/collections.py
+++ b/lib/matplotlib/collections.py
@@ -2002,7 +2002,7 @@ def __init__(self, *args, **kwargs):
             # The following raises a TypeError iif the args don't match.
             w, h, coords, antialiased, shading, kwargs = (
                 lambda meshWidth, meshHeight, coordinates, antialiased=True,
-                       shading=False, **kwargs:
+                       shading='flat', **kwargs:
                 (meshWidth, meshHeight, coordinates, antialiased, shading,
                  kwargs))(*args, **kwargs)
         except TypeError as exc:
@@ -2010,7 +2010,7 @@ def __init__(self, *args, **kwargs):
             # If the following raises a TypeError (i.e. args don't match),
             # just let it propagate.
             coords, antialiased, shading, kwargs = (
-                lambda coordinates, antialiased=True, shading=False, **kwargs:
+                lambda coordinates, antialiased=True, shading='flat', **kwargs:
                 (coordinates, antialiased, shading, kwargs))(*args, **kwargs)
             coords = np.asarray(coords, np.float64)
         else:  # The old signature matched.
diff --git a/lib/matplotlib/tests/test_collections.py b/lib/matplotlib/tests/test_collections.py
index 12d26752f80f..3a12f2fc3fc1 100644
--- a/lib/matplotlib/tests/test_collections.py
+++ b/lib/matplotlib/tests/test_collections.py
@@ -743,6 +743,7 @@ def test_quadmesh_deprecated_signature(
     qmesh = QuadMesh(coords, **kwargs)
     qmesh.set_array(C)
     ax.add_collection(qmesh)
+    assert qmesh._shading == 'flat'
 
     ax = fig_ref.add_subplot()
     ax.set(xlim=(0, 5), ylim=(0, 4))
@@ -754,6 +755,7 @@ def test_quadmesh_deprecated_signature(
                          **kwargs)
     qmesh.set_array(C.flatten() if flat_ref else C)
     ax.add_collection(qmesh)
+    assert qmesh._shading == 'flat'
 
 
 @check_figures_equal(extensions=['png'])