diff --git a/changelog.d/10859.bugfix b/changelog.d/10859.bugfix
new file mode 100644
index 000000000000..c1bfe22d5405
--- /dev/null
+++ b/changelog.d/10859.bugfix
@@ -0,0 +1 @@
+Fix a bug in Unicode support of the room search admin API. It is now possible to search for rooms with non-ASCII characters.
\ No newline at end of file
diff --git a/synapse/rest/admin/rooms.py b/synapse/rest/admin/rooms.py
index ad83d4b54c64..8f781f745fb9 100644
--- a/synapse/rest/admin/rooms.py
+++ b/synapse/rest/admin/rooms.py
@@ -125,7 +125,7 @@ async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
                 errcode=Codes.INVALID_PARAM,
             )
 
-        search_term = parse_string(request, "search_term")
+        search_term = parse_string(request, "search_term", encoding="utf-8")
         if search_term == "":
             raise SynapseError(
                 400,
diff --git a/tests/rest/admin/test_room.py b/tests/rest/admin/test_room.py
index 40e032df7f8c..e798513ac1c9 100644
--- a/tests/rest/admin/test_room.py
+++ b/tests/rest/admin/test_room.py
@@ -941,6 +941,33 @@ def _search_test(
         _search_test(None, "bar")
         _search_test(None, "", expected_http_code=400)
 
+    def test_search_term_non_ascii(self):
+        """Test that searching for a room with non-ASCII characters works correctly"""
+
+        # Create test room
+        room_id = self.helper.create_room_as(self.admin_user, tok=self.admin_user_tok)
+        room_name = "ж"
+
+        # Set the name for the room
+        self.helper.send_state(
+            room_id,
+            "m.room.name",
+            {"name": room_name},
+            tok=self.admin_user_tok,
+        )
+
+        # make the request and test that the response is what we wanted
+        search_term = urllib.parse.quote("ж", "utf-8")
+        url = "/_synapse/admin/v1/rooms?search_term=%s" % (search_term,)
+        channel = self.make_request(
+            "GET",
+            url.encode("ascii"),
+            access_token=self.admin_user_tok,
+        )
+        self.assertEqual(200, channel.code, msg=channel.json_body)
+        self.assertEqual(room_id, channel.json_body.get("rooms")[0].get("room_id"))
+        self.assertEqual("ж", channel.json_body.get("rooms")[0].get("name"))
+
     def test_single_room(self):
         """Test that a single room can be requested correctly"""
         # Create two test rooms