diff --git a/pandas/plotting/_matplotlib/boxplot.py b/pandas/plotting/_matplotlib/boxplot.py
index 32b1fbe73a310..b768a4f623203 100644
--- a/pandas/plotting/_matplotlib/boxplot.py
+++ b/pandas/plotting/_matplotlib/boxplot.py
@@ -212,9 +212,10 @@ def _make_plot(self, fig: Figure) -> None:
 
                     # When `by` is assigned, the ticklabels will become unique grouped
                     # values, instead of label which is used as subtitle in this case.
-                    # error: "Index" has no attribute "levels"; maybe "nlevels"?
-                    levels = self.data.columns.levels  # type: ignore[attr-defined]
-                    ticklabels = [pprint_thing(col) for col in levels[0]]
+                    ticklabels = [
+                        pprint_thing(col)
+                        for col in self.data.columns.get_level_values(0)
+                    ]
                 else:
                     ticklabels = [pprint_thing(label)]
 
diff --git a/pandas/tests/plotting/test_boxplot_method.py b/pandas/tests/plotting/test_boxplot_method.py
index 2267b6197cd80..85c509ac1f965 100644
--- a/pandas/tests/plotting/test_boxplot_method.py
+++ b/pandas/tests/plotting/test_boxplot_method.py
@@ -9,6 +9,7 @@
 import pytest
 
 from pandas import (
+    Categorical,
     DataFrame,
     MultiIndex,
     Series,
@@ -408,6 +409,19 @@ def test_boxplot_group_no_xlabel_ylabel(self, vert, request):
             )
             assert target_label == pprint_thing(["group"])
 
+    @pytest.mark.filterwarnings("ignore:set_ticklabels:UserWarning")
+    def test_boxplot_group_ordered_ticklabel(self, vert):
+        df = DataFrame(
+            {
+                "value": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
+                "label": ["c", "c", "c", "c", "b", "b", "b", "b", "a", "a"],
+            }
+        )
+        df.label = Categorical(df.label, categories=["c", "b", "a"], ordered=True)
+        ax = df.boxplot(by="label")
+        xticklabels = ax.get_xticklabels()
+        assert [x.get_text() for x in xticklabels] == ["c", "b", "a"]
+
 
 class TestDataFrameGroupByPlots:
     def test_boxplot_legacy1(self, hist_df):