diff --git a/changelog.d/14631.bugfix b/changelog.d/14631.bugfix
new file mode 100644
index 000000000000..c5376bab9fdb
--- /dev/null
+++ b/changelog.d/14631.bugfix
@@ -0,0 +1 @@
+Fix a long-standing bug where the user directory would return 1 more row than requested.
\ No newline at end of file
diff --git a/synapse/rest/client/user_directory.py b/synapse/rest/client/user_directory.py
index 116c982ce637..4670fad60868 100644
--- a/synapse/rest/client/user_directory.py
+++ b/synapse/rest/client/user_directory.py
@@ -63,8 +63,8 @@ async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonMapping]:
 
         body = parse_json_object_from_request(request)
 
-        limit = body.get("limit", 10)
-        limit = min(limit, 50)
+        limit = int(body.get("limit", 10))
+        limit = max(min(limit, 50), 0)
 
         try:
             search_term = body["search_term"]
diff --git a/synapse/storage/databases/main/user_directory.py b/synapse/storage/databases/main/user_directory.py
index 044435deab4e..af9952f5139d 100644
--- a/synapse/storage/databases/main/user_directory.py
+++ b/synapse/storage/databases/main/user_directory.py
@@ -886,7 +886,7 @@ async def search_user_dir(
 
         limited = len(results) > limit
 
-        return {"limited": limited, "results": results}
+        return {"limited": limited, "results": results[0:limit]}
 
 
 def _parse_query_sqlite(search_term: str) -> str:
diff --git a/tests/storage/test_user_directory.py b/tests/storage/test_user_directory.py
index 5b60cf5285e4..88c7d5fec051 100644
--- a/tests/storage/test_user_directory.py
+++ b/tests/storage/test_user_directory.py
@@ -448,6 +448,12 @@ def test_search_user_dir_all_users(self) -> None:
             {"user_id": BOBBY, "display_name": "bobby", "avatar_url": None},
         )
 
+    @override_config({"user_directory": {"search_all_users": True}})
+    def test_search_user_limit_correct(self) -> None:
+        r = self.get_success(self.store.search_user_dir(ALICE, "bob", 1))
+        self.assertTrue(r["limited"])
+        self.assertEqual(1, len(r["results"]))
+
     @override_config({"user_directory": {"search_all_users": True}})
     def test_search_user_dir_stop_words(self) -> None:
         """Tests that a user can look up another user by searching for the start if its