diff --git a/homeassistant/components/websocket_api/commands.py b/homeassistant/components/websocket_api/commands.py
index 54539158148..0f52685ca2d 100644
--- a/homeassistant/components/websocket_api/commands.py
+++ b/homeassistant/components/websocket_api/commands.py
@@ -105,7 +105,7 @@ def pong_message(iden: int) -> dict[str, Any]:
 def _forward_events_check_permissions(
     send_message: Callable[[bytes | str | dict[str, Any] | Callable[[], str]], None],
     user: User,
-    msg_id: int,
+    message_id_as_bytes: bytes,
     event: Event,
 ) -> None:
     """Forward state changed events to websocket."""
@@ -118,17 +118,17 @@ def _forward_events_check_permissions(
         and not permissions.check_entity(event.data["entity_id"], POLICY_READ)
     ):
         return
-    send_message(messages.cached_event_message(msg_id, event))
+    send_message(messages.cached_event_message(message_id_as_bytes, event))
 
 
 @callback
 def _forward_events_unconditional(
     send_message: Callable[[bytes | str | dict[str, Any] | Callable[[], str]], None],
-    msg_id: int,
+    message_id_as_bytes: bytes,
     event: Event,
 ) -> None:
     """Forward events to websocket."""
-    send_message(messages.cached_event_message(msg_id, event))
+    send_message(messages.cached_event_message(message_id_as_bytes, event))
 
 
 @callback
@@ -152,16 +152,18 @@ def handle_subscribe_events(
         )
         raise Unauthorized(user_id=connection.user.id)
 
+    message_id_as_bytes = str(msg["id"]).encode()
+
     if event_type == EVENT_STATE_CHANGED:
         forward_events = partial(
             _forward_events_check_permissions,
             connection.send_message,
             connection.user,
-            msg["id"],
+            message_id_as_bytes,
         )
     else:
         forward_events = partial(
-            _forward_events_unconditional, connection.send_message, msg["id"]
+            _forward_events_unconditional, connection.send_message, message_id_as_bytes
         )
 
     connection.subscriptions[msg["id"]] = hass.bus.async_listen(
@@ -366,7 +368,7 @@ def _forward_entity_changes(
     send_message: Callable[[str | bytes | dict[str, Any] | Callable[[], str]], None],
     entity_ids: set[str],
     user: User,
-    msg_id: int,
+    message_id_as_bytes: bytes,
     event: Event[EventStateChangedData],
 ) -> None:
     """Forward entity state changed events to websocket."""
@@ -382,7 +384,7 @@ def _forward_entity_changes(
         and not permissions.check_entity(event.data["entity_id"], POLICY_READ)
     ):
         return
-    send_message(messages.cached_state_diff_message(msg_id, event))
+    send_message(messages.cached_state_diff_message(message_id_as_bytes, event))
 
 
 @callback
@@ -401,6 +403,7 @@ def handle_subscribe_entities(
     # state changed events or we will introduce a race condition
     # where some states are missed
     states = _async_get_allowed_states(hass, connection)
+    message_id_as_bytes = str(msg["id"]).encode()
     connection.subscriptions[msg["id"]] = hass.bus.async_listen(
         EVENT_STATE_CHANGED,
         partial(
@@ -408,7 +411,7 @@ def handle_subscribe_entities(
             connection.send_message,
             entity_ids,
             connection.user,
-            msg["id"],
+            message_id_as_bytes,
         ),
     )
     connection.send_result(msg["id"])
diff --git a/homeassistant/components/websocket_api/messages.py b/homeassistant/components/websocket_api/messages.py
index 75a9c9999d4..98db92dfef7 100644
--- a/homeassistant/components/websocket_api/messages.py
+++ b/homeassistant/components/websocket_api/messages.py
@@ -109,7 +109,7 @@ def event_message(iden: int, event: Any) -> dict[str, Any]:
     return {"id": iden, "type": "event", "event": event}
 
 
-def cached_event_message(iden: int, event: Event) -> bytes:
+def cached_event_message(message_id_as_bytes: bytes, event: Event) -> bytes:
     """Return an event message.
 
     Serialize to json once per message.
@@ -122,7 +122,7 @@ def cached_event_message(iden: int, event: Event) -> bytes:
         (
             _partial_cached_event_message(event)[:-1],
             b',"id":',
-            str(iden).encode(),
+            message_id_as_bytes,
             b"}",
         )
     )
@@ -141,7 +141,9 @@ def _partial_cached_event_message(event: Event) -> bytes:
     )
 
 
-def cached_state_diff_message(iden: int, event: Event[EventStateChangedData]) -> bytes:
+def cached_state_diff_message(
+    message_id_as_bytes: bytes, event: Event[EventStateChangedData]
+) -> bytes:
     """Return an event message.
 
     Serialize to json once per message.
@@ -154,7 +156,7 @@ def cached_state_diff_message(iden: int, event: Event[EventStateChangedData]) ->
         (
             _partial_cached_state_diff_message(event)[:-1],
             b',"id":',
-            str(iden).encode(),
+            message_id_as_bytes,
             b"}",
         )
     )
diff --git a/tests/components/websocket_api/test_messages.py b/tests/components/websocket_api/test_messages.py
index 350aed8b5f7..6294b6a2628 100644
--- a/tests/components/websocket_api/test_messages.py
+++ b/tests/components/websocket_api/test_messages.py
@@ -32,11 +32,11 @@ async def test_cached_event_message(hass: HomeAssistant) -> None:
     assert len(events) == 2
     lru_event_cache.cache_clear()
 
-    msg0 = cached_event_message(2, events[0])
-    assert msg0 == cached_event_message(2, events[0])
+    msg0 = cached_event_message(b"2", events[0])
+    assert msg0 == cached_event_message(b"2", events[0])
 
-    msg1 = cached_event_message(2, events[1])
-    assert msg1 == cached_event_message(2, events[1])
+    msg1 = cached_event_message(b"2", events[1])
+    assert msg1 == cached_event_message(b"2", events[1])
 
     assert msg0 != msg1
 
@@ -45,7 +45,7 @@ async def test_cached_event_message(hass: HomeAssistant) -> None:
     assert cache_info.misses == 2
     assert cache_info.currsize == 2
 
-    cached_event_message(2, events[1])
+    cached_event_message(b"2", events[1])
     cache_info = lru_event_cache.cache_info()
     assert cache_info.hits == 3
     assert cache_info.misses == 2
@@ -70,9 +70,9 @@ async def test_cached_event_message_with_different_idens(hass: HomeAssistant) ->
 
     lru_event_cache.cache_clear()
 
-    msg0 = cached_event_message(2, events[0])
-    msg1 = cached_event_message(3, events[0])
-    msg2 = cached_event_message(4, events[0])
+    msg0 = cached_event_message(b"2", events[0])
+    msg1 = cached_event_message(b"3", events[0])
+    msg2 = cached_event_message(b"4", events[0])
 
     assert msg0 != msg1
     assert msg0 != msg2