diff --git a/pandas/tests/frame/test_indexing.py b/pandas/tests/frame/test_indexing.py
index 61bf91d3018eb..e37f734c6235e 100644
--- a/pandas/tests/frame/test_indexing.py
+++ b/pandas/tests/frame/test_indexing.py
@@ -3881,3 +3881,11 @@ def test_loc_indexing_preserves_index_category_dtype(self):
 
         result = df.loc[["a"]].index.levels[0]
         tm.assert_index_equal(result, expected)
+
+    def test_wrong_length_cat_dtype_raises(self):
+        # GH29523
+        cat = pd.Categorical.from_codes([0, 1, 1, 0, 1, 2], ["a", "b", "c"])
+        df = pd.DataFrame({"bar": range(10)})
+        err = "Length of values does not match length of index"
+        with pytest.raises(ValueError, match=err):
+            df["foo"] = cat