diff --git a/CHANGES.rst b/CHANGES.rst
index 5ebeeb3559..8257611caa 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -17,6 +17,10 @@ Deprecated
 Features added
 --------------
 
+* Add :meth:`~sphinx.application.Sphinx.add_static_dir` for copying static
+  assets from extensions to the build output.
+  Patch by Jared Dillard
+
 Bugs fixed
 ----------
 
diff --git a/doc/extdev/appapi.rst b/doc/extdev/appapi.rst
index c7b17e796a..1f44769f5a 100644
--- a/doc/extdev/appapi.rst
+++ b/doc/extdev/appapi.rst
@@ -71,6 +71,8 @@ package.
 
 .. automethod:: Sphinx.add_css_file
 
+.. automethod:: Sphinx.add_static_dir
+
 .. automethod:: Sphinx.add_latex_package
 
 .. automethod:: Sphinx.add_lexer
diff --git a/doc/usage/configuration.rst b/doc/usage/configuration.rst
index 70de2ca3c1..6bb45d4184 100644
--- a/doc/usage/configuration.rst
+++ b/doc/usage/configuration.rst
@@ -1739,6 +1739,11 @@ and also make use of these options.
       An alternative approach is to use :confval:`html_extra_path`,
       which allows copying dotfiles under the directories.
 
+   .. seealso::
+
+      :meth:`~sphinx.application.Sphinx.add_static_dir`, for use in extensions
+      to copy static files to the output directory.
+
    .. versionchanged:: 0.4
       The paths in :confval:`html_static_path` can now contain subdirectories.
 
diff --git a/sphinx/application.py b/sphinx/application.py
index bac6fd41fd..5349c36ad4 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -10,6 +10,7 @@ import pickle
 import sys
 from collections import deque
 from io import StringIO
+from pathlib import Path
 from typing import TYPE_CHECKING, overload
 
 from docutils.parsers.rst import roles
@@ -37,7 +38,6 @@ from sphinx.util.tags import Tags
 if TYPE_CHECKING:
     import os
     from collections.abc import Callable, Collection, Iterable, Sequence, Set
-    from pathlib import Path
     from typing import IO, Any, Final, Literal
 
     from docutils import nodes
@@ -1484,6 +1484,9 @@ class Sphinx:
         A JavaScript file can be added to the specific HTML page when an extension
         calls this method on :event:`html-page-context` event.
 
+        .. seealso::
+           :meth:`add_static_dir` for copying static files to the output directory
+
         .. versionadded:: 0.5
 
         .. versionchanged:: 1.8
@@ -1549,6 +1552,9 @@ class Sphinx:
         A CSS file can be added to the specific HTML page when an extension calls
         this method on :event:`html-page-context` event.
 
+        .. seealso::
+           :meth:`add_static_dir` for copying static files to the output directory
+
         .. versionadded:: 1.0
 
         .. versionchanged:: 1.6
@@ -1572,6 +1578,42 @@ class Sphinx:
                 filename, priority=priority, **kwargs
             )
 
+    def add_static_dir(self, path: str | os.PathLike[str]) -> None:
+        """Register a static directory to include in HTML output.
+
+        The given directory's contents will be copied to the ``_static``
+        directory during an HTML build. Files from extension static directories
+        are copied after theme static files and before any directories from
+        the user-configured ``html_static_path`` setting.
+
+        Sphinx has built-in support for ``static/`` directories in themes;
+        theme developers should only use this method to register further
+        directories to be copied.
+
+        :param path: The path to a directory containing static files.
+                     This is typically relative to the extension's package
+                     directory.
+
+        Example::
+
+            from pathlib import Path
+
+            def setup(app):
+                # All files in this directory are copied to _static/,
+                # preserving the subdirectory structure
+                app.add_static_dir(Path(__file__).parent / 'static')
+
+                # Add JavaScript and CSS files to HTML pages,
+                # the paths are relative to _static/
+                app.add_js_file('js/my_extension.js')
+                app.add_css_file('css/my_extension.css')
+
+        .. versionadded:: 9.1
+        """
+        path = Path(path)
+        logger.debug("[app] adding static_dir: '%s'", path)
+        self.registry.add_static_dir(path)
+
     def add_latex_package(
         self, packagename: str, options: str | None = None, after_hyperref: bool = False
     ) -> None:
diff --git a/sphinx/builders/html/__init__.py b/sphinx/builders/html/__init__.py
index 37becdeb92..153cfa141c 100644
--- a/sphinx/builders/html/__init__.py
+++ b/sphinx/builders/html/__init__.py
@@ -865,6 +865,15 @@ class StandaloneHTMLBuilder(Builder):
                     force=True,
                 )
 
+    def copy_static_dirs(self) -> None:
+        """Copy static files registered by extensions."""
+        for static_dir in self._registry.static_dirs:
+            if static_dir.is_dir():
+                shutil.copytree(static_dir, self._static_dir, dirs_exist_ok=True)
+            else:
+                msg = __("extension static directory '%s' does not exist")
+                logger.warning(msg, static_dir)
+
     def copy_html_static_files(self, context: dict[str, Any]) -> None:
         def onerror(filename: str, error: Exception) -> None:
             logger.warning(
@@ -916,6 +925,7 @@ class StandaloneHTMLBuilder(Builder):
                 self.copy_translation_js()
                 self.copy_stemmer_js()
                 self.copy_theme_static_files(context)
+                self.copy_static_dirs()
                 self.copy_html_static_files(context)
                 self.copy_html_logo()
                 self.copy_html_favicon()
diff --git a/sphinx/registry.py b/sphinx/registry.py
index df0f7dc32d..da729240b3 100644
--- a/sphinx/registry.py
+++ b/sphinx/registry.py
@@ -22,6 +22,7 @@ from sphinx.util.logging import prefixed_warnings
 if TYPE_CHECKING:
     import os
     from collections.abc import Callable, Iterator, Mapping, Sequence
+    from pathlib import Path
     from typing import Any
 
     from docutils import nodes
@@ -125,6 +126,9 @@ class SphinxComponentRegistry:
         #: js_files; list of JS paths or URLs
         self.js_files: list[tuple[str | None, dict[str, Any]]] = []
 
+        #: static directories registered by extensions
+        self.static_dirs: list[Path] = []
+
         #: LaTeX packages; list of package names and its options
         self.latex_packages: list[tuple[str, str | None]] = []
 
@@ -466,6 +470,11 @@ class SphinxComponentRegistry:
         logger.debug('[app] adding js_file: %r, %r', filename, attributes)
         self.js_files.append((filename, attributes))
 
+    def add_static_dir(self, path: Path) -> None:
+        """Register a static directory for extensions."""
+        logger.debug("[app] adding static_dir: '%s'", path)
+        self.static_dirs.append(path)
+
     def has_latex_package(self, name: str) -> bool:
         packages = self.latex_packages + self.latex_packages_after_hyperref
         return bool([x for x in packages if x[0] == name])
diff --git a/sphinx/util/fileutil.py b/sphinx/util/fileutil.py
index 95fd9c59f1..41a075786f 100644
--- a/sphinx/util/fileutil.py
+++ b/sphinx/util/fileutil.py
@@ -115,6 +115,9 @@ def copy_asset(
 
     Use ``copy_asset_file`` instead to copy a single file.
 
+    Use ``app.add_static_dir()`` instead to copy static files to
+    the output directory.
+
     :param source: The path to source file or directory
     :param destination: The path to destination directory
     :param excluded: The matcher to determine the given path should be copied or not
diff --git a/tests/roots/test-ext_static_dir/conf.py b/tests/roots/test-ext_static_dir/conf.py
new file mode 100644
index 0000000000..9fd5e4c6ce
--- /dev/null
+++ b/tests/roots/test-ext_static_dir/conf.py
@@ -0,0 +1,7 @@
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path.cwd().resolve()))
+
+project = 'Test Extension Static Dir'
+extensions = ['staticdirext']
diff --git a/tests/roots/test-ext_static_dir/index.rst b/tests/roots/test-ext_static_dir/index.rst
new file mode 100644
index 0000000000..ad33d69c39
--- /dev/null
+++ b/tests/roots/test-ext_static_dir/index.rst
@@ -0,0 +1,4 @@
+Test
+====
+
+Content for testing extension static directories.
diff --git a/tests/roots/test-ext_static_dir/staticdirext/__init__.py b/tests/roots/test-ext_static_dir/staticdirext/__init__.py
new file mode 100644
index 0000000000..88f879e42b
--- /dev/null
+++ b/tests/roots/test-ext_static_dir/staticdirext/__init__.py
@@ -0,0 +1,16 @@
+"""Test extension that registers a static directory."""
+
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+
+
+def setup(app):
+    app.add_static_dir(HERE / 'static')
+    app.add_js_file('js/myext.js')
+    app.add_css_file('css/myext.css')
+    return {
+        'version': '1.0',
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }
diff --git a/tests/roots/test-ext_static_dir/staticdirext/static/css/myext.css b/tests/roots/test-ext_static_dir/staticdirext/static/css/myext.css
new file mode 100644
index 0000000000..dd2713f3ce
--- /dev/null
+++ b/tests/roots/test-ext_static_dir/staticdirext/static/css/myext.css
@@ -0,0 +1,2 @@
+/* Extension CSS file */
+.myext { color: blue; }
diff --git a/tests/roots/test-ext_static_dir/staticdirext/static/js/myext.js b/tests/roots/test-ext_static_dir/staticdirext/static/js/myext.js
new file mode 100644
index 0000000000..8216160e2f
--- /dev/null
+++ b/tests/roots/test-ext_static_dir/staticdirext/static/js/myext.js
@@ -0,0 +1,2 @@
+// Extension JavaScript file
+console.log('myext loaded');
diff --git a/tests/test_builders/test_build_html_assets.py b/tests/test_builders/test_build_html_assets.py
index 9059b42322..c730a15546 100644
--- a/tests/test_builders/test_build_html_assets.py
+++ b/tests/test_builders/test_build_html_assets.py
@@ -180,3 +180,26 @@ def test_javscript_loading_method(app: SphinxTestApp) -> None:
     assert '<script src="_static/normal.js"></script>' in content
     assert '<script async="async" src="_static/early.js"></script>' in content
     assert '<script defer="defer" src="_static/late.js"></script>' in content
+
+
+@pytest.mark.sphinx('html', testroot='ext_static_dir')
+def test_extension_static_dir(app: SphinxTestApp) -> None:
+    """Test that extension static directories are copied."""
+    app.build(force_all=True)
+
+    # Verify extension static files were copied to _static
+    assert (app.outdir / '_static' / 'js' / 'myext.js').is_file()
+    assert (app.outdir / '_static' / 'css' / 'myext.css').is_file()
+
+    # Verify JS and CSS are included in the HTML output
+    content = (app.outdir / 'index.html').read_text(encoding='utf8')
+    assert '_static/js/myext.js' in content
+    assert '_static/css/myext.css' in content
+
+
+@pytest.mark.sphinx('html', testroot='ext_static_dir')
+def test_extension_static_dir_registry(app: SphinxTestApp) -> None:
+    """Test that extension static directories are registered in the registry."""
+    # Verify the static dir is registered
+    assert len(app.registry.static_dirs) == 1
+    assert app.registry.static_dirs[0].name == 'static'