diff --git a/homeassistant/components/qnap/sensor.py b/homeassistant/components/qnap/sensor.py
index 4bf410c7f87..dfd03deca16 100644
--- a/homeassistant/components/qnap/sensor.py
+++ b/homeassistant/components/qnap/sensor.py
@@ -351,6 +351,7 @@ class QNAPSensor(CoordinatorEntity[QnapCoordinator], SensorEntity):
             self._attr_unique_id = f"{self._attr_unique_id}_{monitor_device}"
         self._attr_device_info = DeviceInfo(
             identifiers={(DOMAIN, unique_id)},
+            serial_number=unique_id,
             name=self.device_name,
             model=self.coordinator.data["system_stats"]["system"]["model"],
             sw_version=self.coordinator.data["system_stats"]["firmware"]["version"],