diff --git a/changelog.d/9838.misc b/changelog.d/9838.misc
new file mode 100644
index 000000000000..b98ce563093c
--- /dev/null
+++ b/changelog.d/9838.misc
@@ -0,0 +1 @@
+Introduce flake8-bugbear to the test suite and fix some of its lint violations.
\ No newline at end of file
diff --git a/scripts-dev/definitions.py b/scripts-dev/definitions.py
index 313860df139a..c82ddd96776c 100755
--- a/scripts-dev/definitions.py
+++ b/scripts-dev/definitions.py
@@ -140,7 +140,7 @@ def used_names(prefix, item, defs, names):
 
     definitions = {}
     for directory in args.directories:
-        for root, dirs, files in os.walk(directory):
+        for root, _, files in os.walk(directory):
             for filename in files:
                 if filename.endswith(".py"):
                     filepath = os.path.join(root, filename)
diff --git a/scripts-dev/list_url_patterns.py b/scripts-dev/list_url_patterns.py
index 26ad7c67f483..e85420dea876 100755
--- a/scripts-dev/list_url_patterns.py
+++ b/scripts-dev/list_url_patterns.py
@@ -48,7 +48,7 @@ def find_patterns_in_file(filepath):
 
 
 for directory in args.directories:
-    for root, dirs, files in os.walk(directory):
+    for root, _, files in os.walk(directory):
         for filename in files:
             if filename.endswith(".py"):
                 filepath = os.path.join(root, filename)
diff --git a/setup.cfg b/setup.cfg
index 33601b71d58c..e5ceb7ed1933 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -18,8 +18,7 @@ ignore =
 #  E203: whitespace before ':' (which is contrary to pep8?)
 #  E731: do not assign a lambda expression, use a def
 #  E501: Line too long (black enforces this for us)
-#  B007: Subsection of the bugbear suite (TODO: add in remaining fixes)
-ignore=W503,W504,E203,E731,E501,B007
+ignore=W503,W504,E203,E731,E501
 
 [isort]
 line_length = 88
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index 5234e3f81e3f..c831d9f73cee 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -670,7 +670,7 @@ def _verify_third_party_invite(event: EventBase, auth_events: StateMap[EventBase
         public_key = public_key_object["public_key"]
         try:
             for server, signature_block in signed["signatures"].items():
-                for key_name, encoded_signature in signature_block.items():
+                for key_name in signature_block.keys():
                     if not key_name.startswith("ed25519:"):
                         continue
                     verify_key = decode_verify_key_bytes(
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index e3f0bc2471f4..135d88352cab 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -567,10 +567,10 @@ def process_rows_for_federation(
             states=[state], destinations=destinations
         )
 
-    for destination, edu_map in buff.keyed_edus.items():
+    for edu_map in buff.keyed_edus.values():
         for key, edu in edu_map.items():
             transaction_queue.send_edu(edu, key)
 
-    for destination, edu_list in buff.edus.items():
+    for edu_list in buff.edus.values():
         for edu in edu_list:
             transaction_queue.send_edu(edu, None)
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index b8a37b647772..36f2450e2e93 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -1248,7 +1248,7 @@ async def delete_access_tokens_for_user(
 
         # see if any of our auth providers want to know about this
         for provider in self.password_providers:
-            for token, token_id, device_id in tokens_and_devices:
+            for token, _, device_id in tokens_and_devices:
                 await provider.on_logged_out(
                     user_id=user_id, device_id=device_id, access_token=token
                 )
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index d75edb184b3a..c1d780098153 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -156,8 +156,7 @@ async def get_user_ids_changed(
             # The user may have left the room
             # TODO: Check if they actually did or if we were just invited.
             if room_id not in room_ids:
-                for key, event_id in current_state_ids.items():
-                    etype, state_key = key
+                for etype, state_key in current_state_ids.keys():
                     if etype != EventTypes.Member:
                         continue
                     possibly_left.add(state_key)
@@ -179,8 +178,7 @@ async def get_user_ids_changed(
                 log_kv(
                     {"event": "encountered empty previous state", "room_id": room_id}
                 )
-                for key, event_id in current_state_ids.items():
-                    etype, state_key = key
+                for etype, state_key in current_state_ids.keys():
                     if etype != EventTypes.Member:
                         continue
                     possibly_changed.add(state_key)
@@ -198,8 +196,7 @@ async def get_user_ids_changed(
             for state_dict in prev_state_ids.values():
                 member_event = state_dict.get((EventTypes.Member, user_id), None)
                 if not member_event or member_event != current_member_id:
-                    for key, event_id in current_state_ids.items():
-                        etype, state_key = key
+                    for etype, state_key in current_state_ids.keys():
                         if etype != EventTypes.Member:
                             continue
                         possibly_changed.add(state_key)
@@ -714,7 +711,7 @@ async def _handle_device_updates(self, user_id: str) -> None:
                 # This can happen since we batch updates
                 return
 
-            for device_id, stream_id, prev_ids, content in pending_updates:
+            for device_id, stream_id, prev_ids, _ in pending_updates:
                 logger.debug(
                     "Handling update %r/%r, ID: %r, prev: %r ",
                     user_id,
@@ -740,7 +737,7 @@ async def _handle_device_updates(self, user_id: str) -> None:
             else:
                 # Simply update the single device, since we know that is the only
                 # change (because of the single prev_id matching the current cache)
-                for device_id, stream_id, prev_ids, content in pending_updates:
+                for device_id, stream_id, _, content in pending_updates:
                     await self.store.update_remote_device_list_cache_entry(
                         user_id, device_id, content, stream_id
                     )
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 4b3730aa3b7d..dbdd7d2db327 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -2956,7 +2956,7 @@ async def _check_signature(self, event: EventBase, context: EventContext) -> Non
             try:
                 # for each sig on the third_party_invite block of the actual invite
                 for server, signature_block in signed["signatures"].items():
-                    for key_name, encoded_signature in signature_block.items():
+                    for key_name in signature_block.keys():
                         if not key_name.startswith("ed25519:"):
                             continue
 
diff --git a/synapse/logging/_remote.py b/synapse/logging/_remote.py
index 4e8b0f8d10f2..c515690b38f0 100644
--- a/synapse/logging/_remote.py
+++ b/synapse/logging/_remote.py
@@ -226,11 +226,11 @@ def _handle_pressure(self) -> None:
         old_buffer = self._buffer
         self._buffer = deque()
 
-        for i in range(buffer_split):
+        for _ in range(buffer_split):
             self._buffer.append(old_buffer.popleft())
 
         end_buffer = []
-        for i in range(buffer_split):
+        for _ in range(buffer_split):
             end_buffer.append(old_buffer.pop())
 
         self._buffer.extend(reversed(end_buffer))
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index c57ac22e5894..f648678b0903 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -144,7 +144,7 @@ async def query_keys(self, request, query, query_remote_on_cache_miss=False):
 
         # Note that the value is unused.
         cache_misses = {}  # type: Dict[str, Dict[str, int]]
-        for (server_name, key_id, from_server), results in cached.items():
+        for (server_name, key_id, _), results in cached.items():
             results = [(result["ts_added_ms"], result) for result in results]
 
             if not results and key_id is not None:
@@ -206,7 +206,7 @@ async def query_keys(self, request, query, query_remote_on_cache_miss=False):
                 # Cast to bytes since postgresql returns a memoryview.
                 json_results.add(bytes(most_recent_result["key_json"]))
             else:
-                for ts_added, result in results:
+                for _, result in results:
                     # Cast to bytes since postgresql returns a memoryview.
                     json_results.add(bytes(result["key_json"]))
 
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index a362521e20e7..fd25c8112d73 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -170,7 +170,7 @@ async def _persist_events_and_state_updates(
             )
 
         async with stream_ordering_manager as stream_orderings:
-            for (event, context), stream in zip(events_and_contexts, stream_orderings):
+            for (event, _), stream in zip(events_and_contexts, stream_orderings):
                 event.internal_metadata.stream_ordering = stream
 
             await self.db_pool.runInteraction(
@@ -297,7 +297,7 @@ def _get_prevs_before_rejected_txn(txn, batch):
                 txn.execute(sql + clause, args)
                 to_recursively_check = []
 
-                for event_id, prev_event_id, metadata, rejected in txn:
+                for _, prev_event_id, metadata, rejected in txn:
                     if prev_event_id in existing_prevs:
                         continue
 
@@ -1127,7 +1127,7 @@ def _upsert_room_version_txn(self, txn: LoggingTransaction, room_id: str):
     def _update_forward_extremities_txn(
         self, txn, new_forward_extremities, max_stream_order
     ):
-        for room_id, new_extrem in new_forward_extremities.items():
+        for room_id in new_forward_extremities.keys():
             self.db_pool.simple_delete_txn(
                 txn, table="event_forward_extremities", keyvalues={"room_id": room_id}
             )
@@ -1399,7 +1399,7 @@ def get_internal_metadata(event):
         ]
 
         state_values = []
-        for event, context in state_events_and_contexts:
+        for event, _ in state_events_and_contexts:
             vals = {
                 "event_id": event.event_id,
                 "room_id": event.room_id,
@@ -1468,7 +1468,7 @@ def _update_metadata_tables_txn(
             # nothing to do here
             return
 
-        for event, context in events_and_contexts:
+        for event, _ in events_and_contexts:
             if event.type == EventTypes.Redaction and event.redacts is not None:
                 # Remove the entries in the event_push_actions table for the
                 # redacted event.
diff --git a/tests/handlers/test_federation.py b/tests/handlers/test_federation.py
index c7b0975a19e5..8796af45edb4 100644
--- a/tests/handlers/test_federation.py
+++ b/tests/handlers/test_federation.py
@@ -222,7 +222,7 @@ def create_invite():
                 room_version,
             )
 
-        for i in range(3):
+        for _ in range(3):
             event = create_invite()
             self.get_success(
                 self.handler.on_invite_request(
diff --git a/tests/replication/tcp/streams/test_events.py b/tests/replication/tcp/streams/test_events.py
index 323237c1bb88..f51fa0a79e9e 100644
--- a/tests/replication/tcp/streams/test_events.py
+++ b/tests/replication/tcp/streams/test_events.py
@@ -239,7 +239,7 @@ def test_update_function_huge_state_change(self):
 
         # the state rows are unsorted
         state_rows = []  # type: List[EventsStreamCurrentStateRow]
-        for stream_name, token, row in received_rows:
+        for stream_name, _, row in received_rows:
             self.assertEqual("events", stream_name)
             self.assertIsInstance(row, EventsStreamRow)
             self.assertEqual(row.type, "state")
@@ -356,7 +356,7 @@ def test_update_function_state_row_limit(self):
 
             # the state rows are unsorted
             state_rows = []  # type: List[EventsStreamCurrentStateRow]
-            for j in range(STATES_PER_USER + 1):
+            for _ in range(STATES_PER_USER + 1):
                 stream_name, token, row = received_rows.pop(0)
                 self.assertEqual("events", stream_name)
                 self.assertIsInstance(row, EventsStreamRow)
diff --git a/tests/rest/admin/test_device.py b/tests/rest/admin/test_device.py
index ecbee30bb52f..120730b76417 100644
--- a/tests/rest/admin/test_device.py
+++ b/tests/rest/admin/test_device.py
@@ -430,7 +430,7 @@ def test_get_devices(self):
         """
         # Create devices
         number_devices = 5
-        for n in range(number_devices):
+        for _ in range(number_devices):
             self.login("user", "pass")
 
         # Get devices
@@ -547,7 +547,7 @@ def test_delete_devices(self):
 
         # Create devices
         number_devices = 5
-        for n in range(number_devices):
+        for _ in range(number_devices):
             self.login("user", "pass")
 
         # Get devices
diff --git a/tests/rest/admin/test_event_reports.py b/tests/rest/admin/test_event_reports.py
index 8c66da3af406..29341bc6e98f 100644
--- a/tests/rest/admin/test_event_reports.py
+++ b/tests/rest/admin/test_event_reports.py
@@ -48,22 +48,22 @@ def prepare(self, reactor, clock, hs):
         self.helper.join(self.room_id2, user=self.admin_user, tok=self.admin_user_tok)
 
         # Two rooms and two users. Every user sends and reports every room event
-        for i in range(5):
+        for _ in range(5):
             self._create_event_and_report(
                 room_id=self.room_id1,
                 user_tok=self.other_user_tok,
             )
-        for i in range(5):
+        for _ in range(5):
             self._create_event_and_report(
                 room_id=self.room_id2,
                 user_tok=self.other_user_tok,
             )
-        for i in range(5):
+        for _ in range(5):
             self._create_event_and_report(
                 room_id=self.room_id1,
                 user_tok=self.admin_user_tok,
             )
-        for i in range(5):
+        for _ in range(5):
             self._create_event_and_report(
                 room_id=self.room_id2,
                 user_tok=self.admin_user_tok,
diff --git a/tests/rest/admin/test_room.py b/tests/rest/admin/test_room.py
index 6bcd997085dd..6b841881200f 100644
--- a/tests/rest/admin/test_room.py
+++ b/tests/rest/admin/test_room.py
@@ -615,7 +615,7 @@ def test_list_rooms(self):
         # Create 3 test rooms
         total_rooms = 3
         room_ids = []
-        for x in range(total_rooms):
+        for _ in range(total_rooms):
             room_id = self.helper.create_room_as(
                 self.admin_user, tok=self.admin_user_tok
             )
@@ -679,7 +679,7 @@ def test_list_rooms_pagination(self):
         # Create 5 test rooms
         total_rooms = 5
         room_ids = []
-        for x in range(total_rooms):
+        for _ in range(total_rooms):
             room_id = self.helper.create_room_as(
                 self.admin_user, tok=self.admin_user_tok
             )
@@ -1577,7 +1577,7 @@ def test_context_as_admin(self):
             channel.json_body["event"]["event_id"], events[midway]["event_id"]
         )
 
-        for i, found_event in enumerate(channel.json_body["events_before"]):
+        for found_event in channel.json_body["events_before"]:
             for j, posted_event in enumerate(events):
                 if found_event["event_id"] == posted_event["event_id"]:
                     self.assertTrue(j < midway)
@@ -1585,7 +1585,7 @@ def test_context_as_admin(self):
             else:
                 self.fail("Event %s from events_before not found" % j)
 
-        for i, found_event in enumerate(channel.json_body["events_after"]):
+        for found_event in channel.json_body["events_after"]:
             for j, posted_event in enumerate(events):
                 if found_event["event_id"] == posted_event["event_id"]:
                     self.assertTrue(j > midway)
diff --git a/tests/rest/admin/test_statistics.py b/tests/rest/admin/test_statistics.py
index 363bdeeb2dae..79cac4266bf1 100644
--- a/tests/rest/admin/test_statistics.py
+++ b/tests/rest/admin/test_statistics.py
@@ -467,7 +467,7 @@ def _create_media(self, user_token: str, number_media: int):
             number_media: Number of media to be created for the user
         """
         upload_resource = self.media_repo.children[b"upload"]
-        for i in range(number_media):
+        for _ in range(number_media):
             # file size is 67 Byte
             image_data = unhexlify(
                 b"89504e470d0a1a0a0000000d4948445200000001000000010806"
diff --git a/tests/rest/admin/test_user.py b/tests/rest/admin/test_user.py
index 2844c493fc0a..b3afd51522d6 100644
--- a/tests/rest/admin/test_user.py
+++ b/tests/rest/admin/test_user.py
@@ -1937,7 +1937,7 @@ def test_get_rooms(self):
         # Create rooms and join
         other_user_tok = self.login("user", "pass")
         number_rooms = 5
-        for n in range(number_rooms):
+        for _ in range(number_rooms):
             self.helper.create_room_as(self.other_user, tok=other_user_tok)
 
         # Get rooms
@@ -2517,7 +2517,7 @@ def _create_media_for_user(self, user_token: str, number_media: int):
             user_token: Access token of the user
             number_media: Number of media to be created for the user
         """
-        for i in range(number_media):
+        for _ in range(number_media):
             # file size is 67 Byte
             image_data = unhexlify(
                 b"89504e470d0a1a0a0000000d4948445200000001000000010806"
diff --git a/tests/rest/client/v1/test_rooms.py b/tests/rest/client/v1/test_rooms.py
index 92babf65e0f3..a3694f3d0200 100644
--- a/tests/rest/client/v1/test_rooms.py
+++ b/tests/rest/client/v1/test_rooms.py
@@ -646,7 +646,7 @@ def test_invites_by_rooms_ratelimit(self):
     def test_invites_by_users_ratelimit(self):
         """Tests that invites to a specific user are actually rate-limited."""
 
-        for i in range(3):
+        for _ in range(3):
             room_id = self.helper.create_room_as(self.user_id)
             self.helper.invite(room_id, self.user_id, "@other-users:red")
 
@@ -668,7 +668,7 @@ class RoomJoinRatelimitTestCase(RoomBase):
     )
     def test_join_local_ratelimit(self):
         """Tests that local joins are actually rate-limited."""
-        for i in range(3):
+        for _ in range(3):
             self.helper.create_room_as(self.user_id)
 
         self.helper.create_room_as(self.user_id, expect_code=429)
@@ -733,7 +733,7 @@ def test_join_local_ratelimit_idempotent(self):
         for path in paths_to_test:
             # Make sure we send more requests than the rate-limiting config would allow
             # if all of these requests ended up joining the user to a room.
-            for i in range(4):
+            for _ in range(4):
                 channel = self.make_request("POST", path % room_id, {})
                 self.assertEquals(channel.code, 200)
 
diff --git a/tests/storage/test_event_metrics.py b/tests/storage/test_event_metrics.py
index 397e68fe0ad3..088fbb247b50 100644
--- a/tests/storage/test_event_metrics.py
+++ b/tests/storage/test_event_metrics.py
@@ -38,12 +38,12 @@ def test_exposed_to_prometheus(self):
             last_event = None
 
             # Make a real event chain
-            for i in range(event_count):
+            for _ in range(event_count):
                 ev = self.create_and_send_event(room_id, user, False, last_event)
                 last_event = [ev]
 
             # Sprinkle in some extremities
-            for i in range(extrems):
+            for _ in range(extrems):
                 ev = self.create_and_send_event(room_id, user, False, last_event)
 
         # Let it run for a while, then pull out the statistics from the
diff --git a/tests/unittest.py b/tests/unittest.py
index d890ad981f26..ee22a5384935 100644
--- a/tests/unittest.py
+++ b/tests/unittest.py
@@ -133,7 +133,7 @@ def tearDown(orig):
     def assertObjectHasAttributes(self, attrs, obj):
         """Asserts that the given object has each of the attributes given, and
         that the value of each matches according to assertEquals."""
-        for (key, value) in attrs.items():
+        for key in attrs.keys():
             if not hasattr(obj, key):
                 raise AssertionError("Expected obj to have a '.%s'" % key)
             try:
diff --git a/tests/utils.py b/tests/utils.py
index af6b32fc66c2..63d52b91407a 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -303,7 +303,7 @@ def cleanup():
             # database for a few more seconds due to flakiness, preventing
             # us from dropping it when the test is over. If we can't drop
             # it, warn and move on.
-            for x in range(5):
+            for _ in range(5):
                 try:
                     cur.execute("DROP DATABASE IF EXISTS %s;" % (test_db,))
                     db_conn.commit()