diff --git a/homeassistant/components/sensor/mqtt.py b/homeassistant/components/sensor/mqtt.py
index d7d66a3a145..997fd312a6a 100644
--- a/homeassistant/components/sensor/mqtt.py
+++ b/homeassistant/components/sensor/mqtt.py
@@ -15,9 +15,10 @@ from homeassistant.core import callback
 from homeassistant.components.mqtt import (
     CONF_AVAILABILITY_TOPIC, CONF_STATE_TOPIC, CONF_PAYLOAD_AVAILABLE,
     CONF_PAYLOAD_NOT_AVAILABLE, CONF_QOS, MqttAvailability)
+from homeassistant.components.sensor import DEVICE_CLASSES_SCHEMA
 from homeassistant.const import (
     CONF_FORCE_UPDATE, CONF_NAME, CONF_VALUE_TEMPLATE, STATE_UNKNOWN,
-    CONF_UNIT_OF_MEASUREMENT, CONF_ICON)
+    CONF_UNIT_OF_MEASUREMENT, CONF_ICON, CONF_DEVICE_CLASS)
 from homeassistant.helpers.entity import Entity
 import homeassistant.components.mqtt as mqtt
 import homeassistant.helpers.config_validation as cv
@@ -39,6 +40,7 @@ PLATFORM_SCHEMA = mqtt.MQTT_RO_PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
     vol.Optional(CONF_UNIT_OF_MEASUREMENT): cv.string,
     vol.Optional(CONF_ICON): cv.icon,
+    vol.Optional(CONF_DEVICE_CLASS): DEVICE_CLASSES_SCHEMA,
     vol.Optional(CONF_JSON_ATTRS, default=[]): cv.ensure_list_csv,
     vol.Optional(CONF_EXPIRE_AFTER): cv.positive_int,
     vol.Optional(CONF_FORCE_UPDATE, default=DEFAULT_FORCE_UPDATE): cv.boolean,
@@ -66,6 +68,7 @@ async def async_setup_platform(hass: HomeAssistantType, config: ConfigType,
         config.get(CONF_FORCE_UPDATE),
         config.get(CONF_EXPIRE_AFTER),
         config.get(CONF_ICON),
+        config.get(CONF_DEVICE_CLASS),
         value_template,
         config.get(CONF_JSON_ATTRS),
         config.get(CONF_UNIQUE_ID),
@@ -79,8 +82,8 @@ class MqttSensor(MqttAvailability, Entity):
     """Representation of a sensor that can be updated using MQTT."""
 
     def __init__(self, name, state_topic, qos, unit_of_measurement,
-                 force_update, expire_after, icon, value_template,
-                 json_attributes, unique_id: Optional[str],
+                 force_update, expire_after, icon, device_class: Optional[str],
+                 value_template, json_attributes, unique_id: Optional[str],
                  availability_topic, payload_available,
                  payload_not_available):
         """Initialize the sensor."""
@@ -95,6 +98,7 @@ class MqttSensor(MqttAvailability, Entity):
         self._template = value_template
         self._expire_after = expire_after
         self._icon = icon
+        self._device_class = device_class
         self._expiration_trigger = None
         self._json_attributes = set(json_attributes)
         self._unique_id = unique_id
@@ -190,3 +194,8 @@ class MqttSensor(MqttAvailability, Entity):
     def icon(self):
         """Return the icon."""
         return self._icon
+
+    @property
+    def device_class(self) -> Optional[str]:
+        """Return the device class of the sensor."""
+        return self._device_class
diff --git a/tests/components/sensor/test_mqtt.py b/tests/components/sensor/test_mqtt.py
index 88e74e11008..2583f52b3d2 100644
--- a/tests/components/sensor/test_mqtt.py
+++ b/tests/components/sensor/test_mqtt.py
@@ -10,7 +10,8 @@ import homeassistant.components.sensor as sensor
 from homeassistant.const import EVENT_STATE_CHANGED, STATE_UNAVAILABLE
 import homeassistant.util.dt as dt_util
 
-from tests.common import mock_mqtt_component, fire_mqtt_message
+from tests.common import mock_mqtt_component, fire_mqtt_message, \
+    assert_setup_component
 from tests.common import get_test_home_assistant, mock_component
 
 
@@ -350,3 +351,36 @@ class TestSensorMQTT(unittest.TestCase):
         self.hass.block_till_done()
 
         assert len(self.hass.states.all()) == 1
+
+    def test_invalid_device_class(self):
+        """Test device_class option with invalid value."""
+        with assert_setup_component(0):
+            assert setup_component(self.hass, 'sensor', {
+                'sensor': {
+                    'platform': 'mqtt',
+                    'name': 'Test 1',
+                    'state_topic': 'test-topic',
+                    'device_class': 'foobarnotreal'
+                }
+            })
+
+    def test_valid_device_class(self):
+        """Test device_class option with valid values."""
+        assert setup_component(self.hass, 'sensor', {
+            'sensor': [{
+                'platform': 'mqtt',
+                'name': 'Test 1',
+                'state_topic': 'test-topic',
+                'device_class': 'temperature'
+            }, {
+                'platform': 'mqtt',
+                'name': 'Test 2',
+                'state_topic': 'test-topic',
+            }]
+        })
+        self.hass.block_till_done()
+
+        state = self.hass.states.get('sensor.test_1')
+        assert state.attributes['device_class'] == 'temperature'
+        state = self.hass.states.get('sensor.test_2')
+        assert 'device_class' not in state.attributes