diff --git a/changelog.d/11057.misc b/changelog.d/11057.misc
new file mode 100644
index 0000000000..4d412d3e9b
--- /dev/null
+++ b/changelog.d/11057.misc
@@ -0,0 +1 @@
+Add tests for `MediaFilePaths` class.
diff --git a/mypy.ini b/mypy.ini
index 174a6edae6..22768a037d 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -89,6 +89,7 @@ files =
   tests/handlers/test_user_directory.py,
   tests/rest/client/test_login.py,
   tests/rest/client/test_auth.py,
+  tests/rest/media/v1/test_filepath.py,
   tests/storage/test_state.py,
   tests/storage/test_user_directory.py,
   tests/util/test_itertools.py,
diff --git a/tests/rest/media/v1/test_filepath.py b/tests/rest/media/v1/test_filepath.py
new file mode 100644
index 0000000000..09504a485f
--- /dev/null
+++ b/tests/rest/media/v1/test_filepath.py
@@ -0,0 +1,238 @@
+# Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from synapse.rest.media.v1.filepath import MediaFilePaths
+
+from tests import unittest
+
+
+class MediaFilePathsTestCase(unittest.TestCase):
+    def setUp(self):
+        super().setUp()
+
+        self.filepaths = MediaFilePaths("/media_store")
+
+    def test_local_media_filepath(self):
+        """Test local media paths"""
+        self.assertEqual(
+            self.filepaths.local_media_filepath_rel("GerZNDnDZVjsOtardLuwfIBg"),
+            "local_content/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.local_media_filepath("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/local_content/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_local_media_thumbnail(self):
+        """Test local media thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.local_media_thumbnail_rel(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "local_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.local_media_thumbnail(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "/media_store/local_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+
+    def test_local_media_thumbnail_dir(self):
+        """Test local media thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.local_media_thumbnail_dir("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/local_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_remote_media_filepath(self):
+        """Test remote media paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_filepath_rel(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "remote_content/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.remote_media_filepath(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "/media_store/remote_content/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_remote_media_thumbnail(self):
+        """Test remote media thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail_rel(
+                "example.com",
+                "GerZNDnDZVjsOtardLuwfIBg",
+                800,
+                600,
+                "image/jpeg",
+                "scale",
+            ),
+            "remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail(
+                "example.com",
+                "GerZNDnDZVjsOtardLuwfIBg",
+                800,
+                600,
+                "image/jpeg",
+                "scale",
+            ),
+            "/media_store/remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+
+    def test_remote_media_thumbnail_legacy(self):
+        """Test old-style remote media thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail_rel_legacy(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg"
+            ),
+            "remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg",
+        )
+
+    def test_remote_media_thumbnail_dir(self):
+        """Test remote media thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.remote_media_thumbnail_dir(
+                "example.com", "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "/media_store/remote_thumbnail/example.com/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_url_cache_filepath(self):
+        """Test URL cache paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_rel("2020-01-02_GerZNDnDZVjsOtar"),
+            "url_cache/2020-01-02/GerZNDnDZVjsOtar",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_filepath("2020-01-02_GerZNDnDZVjsOtar"),
+            "/media_store/url_cache/2020-01-02/GerZNDnDZVjsOtar",
+        )
+
+    def test_url_cache_filepath_legacy(self):
+        """Test old-style URL cache paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_rel("GerZNDnDZVjsOtardLuwfIBg"),
+            "url_cache/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_filepath("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/url_cache/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_url_cache_filepath_dirs_to_delete(self):
+        """Test URL cache cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_dirs_to_delete(
+                "2020-01-02_GerZNDnDZVjsOtar"
+            ),
+            ["/media_store/url_cache/2020-01-02"],
+        )
+
+    def test_url_cache_filepath_dirs_to_delete_legacy(self):
+        """Test old-style URL cache cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_filepath_dirs_to_delete(
+                "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            [
+                "/media_store/url_cache/Ge/rZ",
+                "/media_store/url_cache/Ge",
+            ],
+        )
+
+    def test_url_cache_thumbnail(self):
+        """Test URL cache thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_rel(
+                "2020-01-02_GerZNDnDZVjsOtar", 800, 600, "image/jpeg", "scale"
+            ),
+            "url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail(
+                "2020-01-02_GerZNDnDZVjsOtar", 800, 600, "image/jpeg", "scale"
+            ),
+            "/media_store/url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar/800-600-image-jpeg-scale",
+        )
+
+    def test_url_cache_thumbnail_legacy(self):
+        """Test old-style URL cache thumbnail paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_rel(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail(
+                "GerZNDnDZVjsOtardLuwfIBg", 800, 600, "image/jpeg", "scale"
+            ),
+            "/media_store/url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg/800-600-image-jpeg-scale",
+        )
+
+    def test_url_cache_thumbnail_directory(self):
+        """Test URL cache thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory_rel(
+                "2020-01-02_GerZNDnDZVjsOtar"
+            ),
+            "url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory("2020-01-02_GerZNDnDZVjsOtar"),
+            "/media_store/url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar",
+        )
+
+    def test_url_cache_thumbnail_directory_legacy(self):
+        """Test old-style URL cache thumbnail directory paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory_rel(
+                "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            "url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_directory("GerZNDnDZVjsOtardLuwfIBg"),
+            "/media_store/url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+        )
+
+    def test_url_cache_thumbnail_dirs_to_delete(self):
+        """Test URL cache thumbnail cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_dirs_to_delete(
+                "2020-01-02_GerZNDnDZVjsOtar"
+            ),
+            [
+                "/media_store/url_cache_thumbnails/2020-01-02/GerZNDnDZVjsOtar",
+                "/media_store/url_cache_thumbnails/2020-01-02",
+            ],
+        )
+
+    def test_url_cache_thumbnail_dirs_to_delete_legacy(self):
+        """Test old-style URL cache thumbnail cleanup paths"""
+        self.assertEqual(
+            self.filepaths.url_cache_thumbnail_dirs_to_delete(
+                "GerZNDnDZVjsOtardLuwfIBg"
+            ),
+            [
+                "/media_store/url_cache_thumbnails/Ge/rZ/NDnDZVjsOtardLuwfIBg",
+                "/media_store/url_cache_thumbnails/Ge/rZ",
+                "/media_store/url_cache_thumbnails/Ge",
+            ],
+        )