diff --git a/homeassistant/components/shelly/sensor.py b/homeassistant/components/shelly/sensor.py
index 6d41a42ad88..1f91cf4844b 100644
--- a/homeassistant/components/shelly/sensor.py
+++ b/homeassistant/components/shelly/sensor.py
@@ -318,7 +318,7 @@ RPC_SENSORS: Final = {
         sub_key="apower",
         name="Power",
         native_unit_of_measurement=UnitOfPower.WATT,
-        value=lambda status, _: round(float(status), 1),
+        value=lambda status, _: None if status is None else round(float(status), 1),
         device_class=SensorDeviceClass.POWER,
         state_class=SensorStateClass.MEASUREMENT,
     ),
@@ -327,7 +327,7 @@ RPC_SENSORS: Final = {
         sub_key="voltage",
         name="Voltage",
         native_unit_of_measurement=UnitOfElectricPotential.VOLT,
-        value=lambda status, _: round(float(status), 1),
+        value=lambda status, _: None if status is None else round(float(status), 1),
         device_class=SensorDeviceClass.VOLTAGE,
         state_class=SensorStateClass.MEASUREMENT,
         entity_registry_enabled_default=False,
diff --git a/tests/components/shelly/test_sensor.py b/tests/components/shelly/test_sensor.py
index 6dcd903219f..d62682df5a9 100644
--- a/tests/components/shelly/test_sensor.py
+++ b/tests/components/shelly/test_sensor.py
@@ -180,6 +180,11 @@ async def test_rpc_sensor(hass, mock_rpc_device, monkeypatch) -> None:
 
     assert hass.states.get(entity_id).state == "88.2"
 
+    mutate_rpc_device_status(monkeypatch, mock_rpc_device, "cover:0", "apower", None)
+    mock_rpc_device.mock_update()
+
+    assert hass.states.get(entity_id).state == STATE_UNKNOWN
+
 
 async def test_rpc_sensor_error(hass, mock_rpc_device, monkeypatch):
     """Test RPC sensor unavailable on sensor error."""