diff --git a/homeassistant/components/mqtt/discovery.py b/homeassistant/components/mqtt/discovery.py
index 29bb44d9e8f..43c07688a43 100644
--- a/homeassistant/components/mqtt/discovery.py
+++ b/homeassistant/components/mqtt/discovery.py
@@ -135,7 +135,7 @@ async def async_start(  # noqa: C901
     @callback
     def async_discovery_message_received(msg: ReceiveMessage) -> None:  # noqa: C901
         """Process the received message."""
-        mqtt_data.last_discovery = time.monotonic()
+        mqtt_data.last_discovery = msg.timestamp
         payload = msg.payload
         topic = msg.topic
         topic_trimmed = topic.replace(f"{discovery_topic}/", "", 1)