diff --git a/homeassistant/components/bme280/sensor.py b/homeassistant/components/bme280/sensor.py
index 2c3ab0303b0..6a54432d190 100644
--- a/homeassistant/components/bme280/sensor.py
+++ b/homeassistant/components/bme280/sensor.py
@@ -12,6 +12,9 @@ from homeassistant.components.sensor import PLATFORM_SCHEMA, SensorEntity
 from homeassistant.const import (
     CONF_MONITORED_CONDITIONS,
     CONF_NAME,
+    DEVICE_CLASS_HUMIDITY,
+    DEVICE_CLASS_PRESSURE,
+    DEVICE_CLASS_TEMPERATURE,
     PERCENTAGE,
     TEMP_FAHRENHEIT,
 )
@@ -48,9 +51,9 @@ SENSOR_TEMP = "temperature"
 SENSOR_HUMID = "humidity"
 SENSOR_PRESS = "pressure"
 SENSOR_TYPES = {
-    SENSOR_TEMP: ["Temperature", None],
-    SENSOR_HUMID: ["Humidity", PERCENTAGE],
-    SENSOR_PRESS: ["Pressure", "mb"],
+    SENSOR_TEMP: ["Temperature", None, DEVICE_CLASS_TEMPERATURE],
+    SENSOR_HUMID: ["Humidity", PERCENTAGE, DEVICE_CLASS_HUMIDITY],
+    SENSOR_PRESS: ["Pressure", "mb", DEVICE_CLASS_PRESSURE],
 }
 DEFAULT_MONITORED = [SENSOR_TEMP, SENSOR_HUMID, SENSOR_PRESS]
 
@@ -146,6 +149,7 @@ class BME280Sensor(SensorEntity):
         self.type = sensor_type
         self._state = None
         self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]
+        self._attr_device_class = SENSOR_TYPES[sensor_type][2]
 
     @property
     def name(self):
diff --git a/homeassistant/components/bme680/sensor.py b/homeassistant/components/bme680/sensor.py
index f3d6b9428ea..6e4e2de79b9 100644
--- a/homeassistant/components/bme680/sensor.py
+++ b/homeassistant/components/bme680/sensor.py
@@ -11,6 +11,9 @@ from homeassistant.components.sensor import PLATFORM_SCHEMA, SensorEntity
 from homeassistant.const import (
     CONF_MONITORED_CONDITIONS,
     CONF_NAME,
+    DEVICE_CLASS_HUMIDITY,
+    DEVICE_CLASS_PRESSURE,
+    DEVICE_CLASS_TEMPERATURE,
     PERCENTAGE,
     TEMP_FAHRENHEIT,
 )
@@ -53,11 +56,11 @@ SENSOR_PRESS = "pressure"
 SENSOR_GAS = "gas"
 SENSOR_AQ = "airquality"
 SENSOR_TYPES = {
-    SENSOR_TEMP: ["Temperature", None],
-    SENSOR_HUMID: ["Humidity", PERCENTAGE],
-    SENSOR_PRESS: ["Pressure", "mb"],
-    SENSOR_GAS: ["Gas Resistance", "Ohms"],
-    SENSOR_AQ: ["Air Quality", PERCENTAGE],
+    SENSOR_TEMP: ["Temperature", None, DEVICE_CLASS_TEMPERATURE],
+    SENSOR_HUMID: ["Humidity", PERCENTAGE, DEVICE_CLASS_HUMIDITY],
+    SENSOR_PRESS: ["Pressure", "mb", DEVICE_CLASS_PRESSURE],
+    SENSOR_GAS: ["Gas Resistance", "Ohms", None],
+    SENSOR_AQ: ["Air Quality", PERCENTAGE, None],
 }
 DEFAULT_MONITORED = [SENSOR_TEMP, SENSOR_HUMID, SENSOR_PRESS, SENSOR_AQ]
 OVERSAMPLING_VALUES = {0, 1, 2, 4, 8, 16}
@@ -327,6 +330,7 @@ class BME680Sensor(SensorEntity):
         self.type = sensor_type
         self._state = None
         self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]
+        self._attr_device_class = SENSOR_TYPES[sensor_type][2]
 
     @property
     def name(self):
diff --git a/homeassistant/components/dht/sensor.py b/homeassistant/components/dht/sensor.py
index 72780832960..1300c165b37 100644
--- a/homeassistant/components/dht/sensor.py
+++ b/homeassistant/components/dht/sensor.py
@@ -12,6 +12,8 @@ from homeassistant.const import (
     CONF_MONITORED_CONDITIONS,
     CONF_NAME,
     CONF_PIN,
+    DEVICE_CLASS_HUMIDITY,
+    DEVICE_CLASS_TEMPERATURE,
     PERCENTAGE,
     TEMP_FAHRENHEIT,
 )
@@ -33,8 +35,8 @@ MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=30)
 SENSOR_TEMPERATURE = "temperature"
 SENSOR_HUMIDITY = "humidity"
 SENSOR_TYPES = {
-    SENSOR_TEMPERATURE: ["Temperature", None],
-    SENSOR_HUMIDITY: ["Humidity", PERCENTAGE],
+    SENSOR_TEMPERATURE: ["Temperature", None, DEVICE_CLASS_TEMPERATURE],
+    SENSOR_HUMIDITY: ["Humidity", PERCENTAGE, DEVICE_CLASS_HUMIDITY],
 }
 
 
@@ -124,6 +126,7 @@ class DHTSensor(SensorEntity):
         self.humidity_offset = humidity_offset
         self._state = None
         self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]
+        self._attr_device_class = SENSOR_TYPES[sensor_type][2]
 
     @property
     def name(self):
diff --git a/homeassistant/components/ecobee/sensor.py b/homeassistant/components/ecobee/sensor.py
index 275db46ab0a..24ba36bedd8 100644
--- a/homeassistant/components/ecobee/sensor.py
+++ b/homeassistant/components/ecobee/sensor.py
@@ -12,8 +12,8 @@ from homeassistant.const import (
 from .const import DOMAIN, ECOBEE_MODEL_TO_NAME, MANUFACTURER
 
 SENSOR_TYPES = {
-    "temperature": ["Temperature", TEMP_FAHRENHEIT],
-    "humidity": ["Humidity", PERCENTAGE],
+    "temperature": ["Temperature", TEMP_FAHRENHEIT, DEVICE_CLASS_TEMPERATURE],
+    "humidity": ["Humidity", PERCENTAGE, DEVICE_CLASS_HUMIDITY],
 }
 
 
@@ -44,6 +44,7 @@ class EcobeeSensor(SensorEntity):
         self.index = sensor_index
         self._state = None
         self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]
+        self._attr_device_class = SENSOR_TYPES[sensor_type][2]
 
     @property
     def name(self):
diff --git a/homeassistant/components/greeneye_monitor/sensor.py b/homeassistant/components/greeneye_monitor/sensor.py
index 337a471eb2b..0aa106e6801 100644
--- a/homeassistant/components/greeneye_monitor/sensor.py
+++ b/homeassistant/components/greeneye_monitor/sensor.py
@@ -4,6 +4,7 @@ from homeassistant.const import (
     CONF_NAME,
     CONF_SENSOR_TYPE,
     CONF_TEMPERATURE_UNIT,
+    DEVICE_CLASS_TEMPERATURE,
     POWER_WATT,
     TIME_HOURS,
     TIME_MINUTES,
@@ -240,6 +241,7 @@ class PulseCounter(GEMSensor):
 class TemperatureSensor(GEMSensor):
     """Entity showing temperature from one temperature sensor."""
 
+    _attr_device_class = DEVICE_CLASS_TEMPERATURE
     _attr_icon = TEMPERATURE_ICON
 
     def __init__(self, monitor_serial_number, number, name, unit):
diff --git a/homeassistant/components/htu21d/sensor.py b/homeassistant/components/htu21d/sensor.py
index d32eebf6d5f..ccbe6a31de2 100644
--- a/homeassistant/components/htu21d/sensor.py
+++ b/homeassistant/components/htu21d/sensor.py
@@ -8,7 +8,13 @@ import smbus
 import voluptuous as vol
 
 from homeassistant.components.sensor import PLATFORM_SCHEMA, SensorEntity
-from homeassistant.const import CONF_NAME, PERCENTAGE, TEMP_FAHRENHEIT
+from homeassistant.const import (
+    CONF_NAME,
+    DEVICE_CLASS_HUMIDITY,
+    DEVICE_CLASS_TEMPERATURE,
+    PERCENTAGE,
+    TEMP_FAHRENHEIT,
+)
 import homeassistant.helpers.config_validation as cv
 from homeassistant.util import Throttle
 from homeassistant.util.temperature import celsius_to_fahrenheit
@@ -32,6 +38,11 @@ PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
     }
 )
 
+DEVICE_CLASS_MAP = {
+    SENSOR_TEMPERATURE: DEVICE_CLASS_TEMPERATURE,
+    SENSOR_HUMIDITY: DEVICE_CLASS_HUMIDITY,
+}
+
 
 async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
     """Set up the HTU21D sensor."""
@@ -79,6 +90,7 @@ class HTU21DSensor(SensorEntity):
         self._unit_of_measurement = unit
         self._client = htu21d_client
         self._state = None
+        self._attr_device_class = DEVICE_CLASS_MAP[variable]
 
     @property
     def name(self) -> str:
diff --git a/homeassistant/components/mhz19/sensor.py b/homeassistant/components/mhz19/sensor.py
index 0f0735dd5da..63a1181f720 100644
--- a/homeassistant/components/mhz19/sensor.py
+++ b/homeassistant/components/mhz19/sensor.py
@@ -11,6 +11,8 @@ from homeassistant.const import (
     CONCENTRATION_PARTS_PER_MILLION,
     CONF_MONITORED_CONDITIONS,
     CONF_NAME,
+    DEVICE_CLASS_CO2,
+    DEVICE_CLASS_TEMPERATURE,
     TEMP_FAHRENHEIT,
 )
 import homeassistant.helpers.config_validation as cv
@@ -29,8 +31,8 @@ ATTR_CO2_CONCENTRATION = "co2_concentration"
 SENSOR_TEMPERATURE = "temperature"
 SENSOR_CO2 = "co2"
 SENSOR_TYPES = {
-    SENSOR_TEMPERATURE: ["Temperature", None],
-    SENSOR_CO2: ["CO2", CONCENTRATION_PARTS_PER_MILLION],
+    SENSOR_TEMPERATURE: ["Temperature", None, DEVICE_CLASS_TEMPERATURE],
+    SENSOR_CO2: ["CO2", CONCENTRATION_PARTS_PER_MILLION, DEVICE_CLASS_CO2],
 }
 PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
     {
@@ -80,6 +82,7 @@ class MHZ19Sensor(SensorEntity):
         self._unit_of_measurement = SENSOR_TYPES[sensor_type][1]
         self._ppm = None
         self._temperature = None
+        self._attr_device_class = SENSOR_TYPES[sensor_type][2]
 
     @property
     def name(self):
diff --git a/homeassistant/components/mysensors/sensor.py b/homeassistant/components/mysensors/sensor.py
index 6a5c80e1e8a..1cb2b632362 100644
--- a/homeassistant/components/mysensors/sensor.py
+++ b/homeassistant/components/mysensors/sensor.py
@@ -115,14 +115,12 @@ class MySensorsSensor(mysensors.device.MySensorsEntity, SensorEntity):
     @property
     def device_class(self) -> str | None:
         """Return the device class of this entity."""
-        icon = self._get_sensor_type()[2]
-        return icon
+        return self._get_sensor_type()[2]
 
     @property
     def icon(self) -> str | None:
         """Return the icon to use in the frontend, if any."""
-        icon = self._get_sensor_type()[1]
-        return icon
+        return self._get_sensor_type()[1]
 
     @property
     def unit_of_measurement(self) -> str | None:
diff --git a/homeassistant/components/temper/sensor.py b/homeassistant/components/temper/sensor.py
index 7edbd3ba812..7d447d3f9ea 100644
--- a/homeassistant/components/temper/sensor.py
+++ b/homeassistant/components/temper/sensor.py
@@ -8,6 +8,7 @@ from homeassistant.components.sensor import PLATFORM_SCHEMA, SensorEntity
 from homeassistant.const import (
     CONF_NAME,
     CONF_OFFSET,
+    DEVICE_CLASS_TEMPERATURE,
     DEVICE_DEFAULT_NAME,
     TEMP_FAHRENHEIT,
 )
@@ -68,6 +69,7 @@ class TemperSensor(SensorEntity):
         self.current_value = None
         self._name = name
         self.set_temper_device(temper_device)
+        self._attr_device_class = DEVICE_CLASS_TEMPERATURE
 
     @property
     def name(self):
diff --git a/homeassistant/components/thermoworks_smoke/sensor.py b/homeassistant/components/thermoworks_smoke/sensor.py
index 86427349f31..1bdbbc5fcc3 100644
--- a/homeassistant/components/thermoworks_smoke/sensor.py
+++ b/homeassistant/components/thermoworks_smoke/sensor.py
@@ -18,6 +18,7 @@ from homeassistant.const import (
     CONF_EXCLUDE,
     CONF_MONITORED_CONDITIONS,
     CONF_PASSWORD,
+    DEVICE_CLASS_TEMPERATURE,
     TEMP_FAHRENHEIT,
 )
 import homeassistant.helpers.config_validation as cv
@@ -105,6 +106,7 @@ class ThermoworksSmokeSensor(SensorEntity):
         self._unique_id = f"{serial}-{sensor_type}"
         self.serial = serial
         self.mgr = mgr
+        self._attr_device_class = DEVICE_CLASS_TEMPERATURE
         self.update_unit()
 
     @property
diff --git a/homeassistant/components/waterfurnace/sensor.py b/homeassistant/components/waterfurnace/sensor.py
index fe7c94ed634..8691cc4ed02 100644
--- a/homeassistant/components/waterfurnace/sensor.py
+++ b/homeassistant/components/waterfurnace/sensor.py
@@ -1,7 +1,12 @@
 """Support for Waterfurnace."""
 
 from homeassistant.components.sensor import ENTITY_ID_FORMAT, SensorEntity
-from homeassistant.const import PERCENTAGE, POWER_WATT, TEMP_FAHRENHEIT
+from homeassistant.const import (
+    DEVICE_CLASS_TEMPERATURE,
+    PERCENTAGE,
+    POWER_WATT,
+    TEMP_FAHRENHEIT,
+)
 from homeassistant.core import callback
 from homeassistant.util import slugify
 
@@ -12,9 +17,15 @@ class WFSensorConfig:
     """Water Furnace Sensor configuration."""
 
     def __init__(
-        self, friendly_name, field, icon="mdi:gauge", unit_of_measurement=None
+        self,
+        friendly_name,
+        field,
+        icon="mdi:gauge",
+        unit_of_measurement=None,
+        device_class=None,
     ):
         """Initialize configuration."""
+        self.device_class = device_class
         self.friendly_name = friendly_name
         self.field = field
         self.icon = icon
@@ -25,13 +36,19 @@ SENSORS = [
     WFSensorConfig("Furnace Mode", "mode"),
     WFSensorConfig("Total Power", "totalunitpower", "mdi:flash", POWER_WATT),
     WFSensorConfig(
-        "Active Setpoint", "tstatactivesetpoint", "mdi:thermometer", TEMP_FAHRENHEIT
+        "Active Setpoint",
+        "tstatactivesetpoint",
+        None,
+        TEMP_FAHRENHEIT,
+        DEVICE_CLASS_TEMPERATURE,
     ),
-    WFSensorConfig("Leaving Air", "leavingairtemp", "mdi:thermometer", TEMP_FAHRENHEIT),
-    WFSensorConfig("Room Temp", "tstatroomtemp", "mdi:thermometer", TEMP_FAHRENHEIT),
     WFSensorConfig(
-        "Loop Temp", "enteringwatertemp", "mdi:thermometer", TEMP_FAHRENHEIT
+        "Leaving Air", "leavingairtemp", None, TEMP_FAHRENHEIT, DEVICE_CLASS_TEMPERATURE
     ),
+    WFSensorConfig(
+        "Room Temp", "tstatroomtemp", None, TEMP_FAHRENHEIT, DEVICE_CLASS_TEMPERATURE
+    ),
+    WFSensorConfig("Loop Temp", "enteringwatertemp", None, TEMP_FAHRENHEIT),
     WFSensorConfig(
         "Humidity Set Point", "tstathumidsetpoint", "mdi:water-percent", PERCENTAGE
     ),
@@ -71,6 +88,7 @@ class WaterFurnaceSensor(SensorEntity):
         self._state = None
         self._icon = config.icon
         self._unit_of_measurement = config.unit_of_measurement
+        self._attr_device_class = config.device_class
 
         # This ensures that the sensors are isolated per waterfurnace unit
         self.entity_id = ENTITY_ID_FORMAT.format(