diff --git a/homeassistant/components/ecowitt/sensor.py b/homeassistant/components/ecowitt/sensor.py
index 631910bde86..6990bf56099 100644
--- a/homeassistant/components/ecowitt/sensor.py
+++ b/homeassistant/components/ecowitt/sensor.py
@@ -253,6 +253,7 @@ ECOWITT_SENSORS_MAPPING: Final = {
     ),
     EcoWittSensorTypes.PM4: SensorEntityDescription(
         key="PM4",
+        device_class=SensorDeviceClass.PM4,
         native_unit_of_measurement=CONCENTRATION_MICROGRAMS_PER_CUBIC_METER,
         state_class=SensorStateClass.MEASUREMENT,
     ),