diff --git a/doc/missing-references.json b/doc/missing-references.json
index 1061b08b7fe6..364885ab3a74 100644
--- a/doc/missing-references.json
+++ b/doc/missing-references.json
@@ -152,6 +152,9 @@
     "HashableList": [
       "lib/matplotlib/pyplot.py:docstring of matplotlib.pyplot.subplot_mosaic:1"
     ],
+    "HashableList[_HT]": [
+      "doc/docstring of builtins.list:17"
+    ],
     "LineStyleType": [
       "lib/matplotlib/pyplot.py:docstring of matplotlib.pyplot.eventplot:1",
       "lib/matplotlib/pyplot.py:docstring of matplotlib.pyplot.hlines:1",
@@ -701,6 +704,9 @@
     "matplotlib.animation.TimedAnimation.to_jshtml": [
       "doc/api/_as_gen/matplotlib.animation.TimedAnimation.rst:28:<autosummary>:1"
     ],
+    "matplotlib.typing._HT": [
+      "doc/docstring of builtins.list:17"
+    ],
     "mpl_toolkits.axislines.Axes": [
       "lib/mpl_toolkits/axisartist/axis_artist.py:docstring of mpl_toolkits.axisartist.axis_artist:7"
     ],
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
index fe997d35372c..9a75811fe13f 100644
--- a/lib/matplotlib/figure.py
+++ b/lib/matplotlib/figure.py
@@ -1812,15 +1812,11 @@ def _norm_per_subplot_kw(per_subplot_kw):
             if isinstance(k, tuple):
                 for sub_key in k:
                     if sub_key in expanded:
-                        raise ValueError(
-                            f'The key {sub_key!r} appears multiple times.'
-                            )
+                        raise ValueError(f'The key {sub_key!r} appears multiple times.')
                     expanded[sub_key] = v
             else:
                 if k in expanded:
-                    raise ValueError(
-                        f'The key {k!r} appears multiple times.'
-                    )
+                    raise ValueError(f'The key {k!r} appears multiple times.')
                 expanded[k] = v
         return expanded
 
diff --git a/lib/matplotlib/figure.pyi b/lib/matplotlib/figure.pyi
index 40e8fce0321f..887b6ed5d86e 100644
--- a/lib/matplotlib/figure.pyi
+++ b/lib/matplotlib/figure.pyi
@@ -1,4 +1,9 @@
+from collections.abc import Callable, Hashable, Iterable
 import os
+from typing import Any, IO, Literal, TypeVar, overload
+
+import numpy as np
+from numpy.typing import ArrayLike
 
 from matplotlib.artist import Artist
 from matplotlib.axes import Axes, SubplotBase
@@ -19,14 +24,10 @@ from matplotlib.lines import Line2D
 from matplotlib.patches import Rectangle, Patch
 from matplotlib.text import Text
 from matplotlib.transforms import Affine2D, Bbox, BboxBase, Transform
-
-import numpy as np
-from numpy.typing import ArrayLike
-
-from collections.abc import Callable, Iterable
-from typing import Any, IO, Literal, overload
 from .typing import ColorType, HashableList
 
+_T = TypeVar("_T")
+
 class SubplotParams:
     def __init__(
         self,
@@ -226,11 +227,38 @@ class FigureBase(Artist):
         *,
         bbox_extra_artists: Iterable[Artist] | None = ...,
     ) -> Bbox: ...
-
-    # Any in list of list is recursive list[list[Hashable | list[Hashable | ...]]] but that can't really be type checked
+    @overload
     def subplot_mosaic(
         self,
-        mosaic: str | HashableList,
+        mosaic: str,
+        *,
+        sharex: bool = ...,
+        sharey: bool = ...,
+        width_ratios: ArrayLike | None = ...,
+        height_ratios: ArrayLike | None = ...,
+        empty_sentinel: str = ...,
+        subplot_kw: dict[str, Any] | None = ...,
+        per_subplot_kw: dict[str | tuple[str, ...], dict[str, Any]] | None = ...,
+        gridspec_kw: dict[str, Any] | None = ...,
+    ) -> dict[str, Axes]: ...
+    @overload
+    def subplot_mosaic(
+        self,
+        mosaic: list[HashableList[_T]],
+        *,
+        sharex: bool = ...,
+        sharey: bool = ...,
+        width_ratios: ArrayLike | None = ...,
+        height_ratios: ArrayLike | None = ...,
+        empty_sentinel: _T = ...,
+        subplot_kw: dict[str, Any] | None = ...,
+        per_subplot_kw: dict[_T | tuple[_T, ...], dict[str, Any]] | None = ...,
+        gridspec_kw: dict[str, Any] | None = ...,
+    ) -> dict[_T, Axes]: ...
+    @overload
+    def subplot_mosaic(
+        self,
+        mosaic: list[HashableList[Hashable]],
         *,
         sharex: bool = ...,
         sharey: bool = ...,
@@ -238,9 +266,9 @@ class FigureBase(Artist):
         height_ratios: ArrayLike | None = ...,
         empty_sentinel: Any = ...,
         subplot_kw: dict[str, Any] | None = ...,
-        per_subplot_kw: dict[Any, dict[str, Any]] | None = ...,
-        gridspec_kw: dict[str, Any] | None = ...
-    ) -> dict[Any, Axes]: ...
+        per_subplot_kw: dict[Hashable | tuple[Hashable, ...], dict[str, Any]] | None = ...,
+        gridspec_kw: dict[str, Any] | None = ...,
+    ) -> dict[Hashable, Axes]: ...
 
 class SubFigure(FigureBase):
     figure: Figure
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
index cc18b6b21bf0..00e5dea071a4 100644
--- a/lib/matplotlib/pyplot.py
+++ b/lib/matplotlib/pyplot.py
@@ -125,6 +125,7 @@
 
     _P = ParamSpec('_P')
     _R = TypeVar('_R')
+    _T = TypeVar('_T')
 
 
 # We may not need the following imports here:
@@ -1602,8 +1603,56 @@ def subplots(
     return fig, axs
 
 
+@overload
+def subplot_mosaic(
+    mosaic: str,
+    *,
+    sharex: bool = ...,
+    sharey: bool = ...,
+    width_ratios: ArrayLike | None = ...,
+    height_ratios: ArrayLike | None = ...,
+    empty_sentinel: str = ...,
+    subplot_kw: dict[str, Any] | None = ...,
+    gridspec_kw: dict[str, Any] | None = ...,
+    per_subplot_kw: dict[str | tuple[str, ...], dict[str, Any]] | None = ...,
+    **fig_kw: Any
+) -> tuple[Figure, dict[str, matplotlib.axes.Axes]]: ...
+
+
+@overload
+def subplot_mosaic(
+    mosaic: list[HashableList[_T]],
+    *,
+    sharex: bool = ...,
+    sharey: bool = ...,
+    width_ratios: ArrayLike | None = ...,
+    height_ratios: ArrayLike | None = ...,
+    empty_sentinel: _T = ...,
+    subplot_kw: dict[str, Any] | None = ...,
+    gridspec_kw: dict[str, Any] | None = ...,
+    per_subplot_kw: dict[_T | tuple[_T, ...], dict[str, Any]] | None = ...,
+    **fig_kw: Any
+) -> tuple[Figure, dict[_T, matplotlib.axes.Axes]]: ...
+
+
+@overload
+def subplot_mosaic(
+    mosaic: list[HashableList[Hashable]],
+    *,
+    sharex: bool = ...,
+    sharey: bool = ...,
+    width_ratios: ArrayLike | None = ...,
+    height_ratios: ArrayLike | None = ...,
+    empty_sentinel: Any = ...,
+    subplot_kw: dict[str, Any] | None = ...,
+    gridspec_kw: dict[str, Any] | None = ...,
+    per_subplot_kw: dict[Hashable | tuple[Hashable, ...], dict[str, Any]] | None = ...,
+    **fig_kw: Any
+) -> tuple[Figure, dict[Hashable, matplotlib.axes.Axes]]: ...
+
+
 def subplot_mosaic(
-    mosaic: str | HashableList,
+    mosaic: str | list[HashableList[_T]] | list[HashableList[Hashable]],
     *,
     sharex: bool = False,
     sharey: bool = False,
@@ -1612,9 +1661,13 @@ def subplot_mosaic(
     empty_sentinel: Any = '.',
     subplot_kw: dict[str, Any] | None = None,
     gridspec_kw: dict[str, Any] | None = None,
-    per_subplot_kw: dict[Hashable, dict[str, Any]] | None = None,
-    **fig_kw
-) -> tuple[Figure, dict[Hashable, matplotlib.axes.Axes]]:
+    per_subplot_kw: dict[str | tuple[str, ...], dict[str, Any]] |
+                    dict[_T | tuple[_T, ...], dict[str, Any]] |
+                    dict[Hashable | tuple[Hashable, ...], dict[str, Any]] | None = None,
+    **fig_kw: Any
+) -> tuple[Figure, dict[str, matplotlib.axes.Axes]] | \
+     tuple[Figure, dict[_T, matplotlib.axes.Axes]] | \
+     tuple[Figure, dict[Hashable, matplotlib.axes.Axes]]:
     """
     Build a layout of Axes based on ASCII art or nested lists.
 
@@ -1716,12 +1769,13 @@ def subplot_mosaic(
 
     """
     fig = figure(**fig_kw)
-    ax_dict = fig.subplot_mosaic(
-        mosaic, sharex=sharex, sharey=sharey,
+    ax_dict = fig.subplot_mosaic(  # type: ignore[misc]
+        mosaic,  # type: ignore[arg-type]
+        sharex=sharex, sharey=sharey,
         height_ratios=height_ratios, width_ratios=width_ratios,
         subplot_kw=subplot_kw, gridspec_kw=gridspec_kw,
         empty_sentinel=empty_sentinel,
-        per_subplot_kw=per_subplot_kw,
+        per_subplot_kw=per_subplot_kw,  # type: ignore[arg-type]
     )
     return fig, ax_dict
 
diff --git a/lib/matplotlib/typing.py b/lib/matplotlib/typing.py
index e6b9ada7d8a2..02059be94ba2 100644
--- a/lib/matplotlib/typing.py
+++ b/lib/matplotlib/typing.py
@@ -11,7 +11,7 @@
 """
 from collections.abc import Hashable, Sequence
 import pathlib
-from typing import Any, Literal, Union
+from typing import Any, Literal, TypeVar, Union
 
 from . import path
 from ._enums import JoinStyle, CapStyle
@@ -55,5 +55,6 @@
     Sequence[Union[str, pathlib.Path, dict[str, Any]]],
 ]
 
-HashableList = list[Union[Hashable, "HashableList"]]
+_HT = TypeVar("_HT", bound=Hashable)
+HashableList = list[Union[_HT, "HashableList[_HT]"]]
 """A nested list of Hashable values."""