diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
index 44e57389cdbb..8bbb31aa8cc5 100644
--- a/lib/matplotlib/figure.py
+++ b/lib/matplotlib/figure.py
@@ -1776,8 +1776,13 @@ def get_tightbbox(self, renderer, bbox_extra_artists=None):
 
     @staticmethod
     def _normalize_grid_string(layout):
-        layout = inspect.cleandoc(layout)
-        return [list(ln) for ln in layout.strip('\n').split('\n')]
+        if '\n' not in layout:
+            # single-line string
+            return [list(ln) for ln in layout.split(';')]
+        else:
+            # multi-line string
+            layout = inspect.cleandoc(layout)
+            return [list(ln) for ln in layout.strip('\n').split('\n')]
 
     def subplot_mosaic(self, layout, *, subplot_kw=None, gridspec_kw=None,
                        empty_sentinel='.'):
@@ -1812,16 +1817,21 @@ def subplot_mosaic(self, layout, *, subplot_kw=None, gridspec_kw=None,
             Any of the entries in the layout can be a list of lists
             of the same form to create nested layouts.
 
-            If input is a str, then it must be of the form ::
+            If input is a str, then it can either be a multi-line string of
+            the form ::
 
               '''
               AAE
               C.E
               '''
 
-            where each character is a column and each line is a row.
-            This only allows only single character Axes labels and does
-            not allow nesting but is very terse.
+            where each character is a column and each line is a row. Or it
+            can be a single-line string where rows are separated by ``;``::
+
+              'AB;CC'
+
+            The string notation allows only single character Axes labels and
+            does not support nesting but is very terse.
 
         subplot_kw : dict, optional
             Dictionary with keywords passed to the `.Figure.add_subplot` call
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
index 9db229eb29ca..44f094781a00 100644
--- a/lib/matplotlib/tests/test_figure.py
+++ b/lib/matplotlib/tests/test_figure.py
@@ -758,6 +758,24 @@ def test_subplot_kw(self, fig_test, fig_ref, subplot_kw):
 
         axB = fig_ref.add_subplot(gs[0, 1], **subplot_kw)
 
+    def test_string_parser(self):
+        normalize = Figure._normalize_grid_string
+        assert normalize('ABC') == [['A', 'B', 'C']]
+        assert normalize('AB;CC') == [['A', 'B'], ['C', 'C']]
+        assert normalize('AB;CC;DE') == [['A', 'B'], ['C', 'C'], ['D', 'E']]
+        assert normalize("""
+                         ABC
+                         """) == [['A', 'B', 'C']]
+        assert normalize("""
+                         AB
+                         CC
+                         """) == [['A', 'B'], ['C', 'C']]
+        assert normalize("""
+                         AB
+                         CC
+                         DE
+                         """) == [['A', 'B'], ['C', 'C'], ['D', 'E']]
+
     @check_figures_equal(extensions=["png"])
     @pytest.mark.parametrize("str_pattern",
                              ["AAA\nBBB", "\nAAA\nBBB\n", "ABC\nDEF"]