diff --git a/homeassistant/components/switch/mqtt.py b/homeassistant/components/switch/mqtt.py
index 69f12536c5f..1075888e199 100644
--- a/homeassistant/components/switch/mqtt.py
+++ b/homeassistant/components/switch/mqtt.py
@@ -5,6 +5,7 @@ For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/switch.mqtt/
 """
 import logging
+from typing import Optional
 
 import voluptuous as vol
 
@@ -29,12 +30,14 @@ DEFAULT_NAME = 'MQTT Switch'
 DEFAULT_PAYLOAD_ON = 'ON'
 DEFAULT_PAYLOAD_OFF = 'OFF'
 DEFAULT_OPTIMISTIC = False
+CONF_UNIQUE_ID = 'unique_id'
 
 PLATFORM_SCHEMA = mqtt.MQTT_RW_PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
     vol.Optional(CONF_ICON): cv.icon,
     vol.Optional(CONF_PAYLOAD_ON, default=DEFAULT_PAYLOAD_ON): cv.string,
     vol.Optional(CONF_PAYLOAD_OFF, default=DEFAULT_PAYLOAD_OFF): cv.string,
+    vol.Optional(CONF_UNIQUE_ID): cv.string,
     vol.Optional(CONF_OPTIMISTIC, default=DEFAULT_OPTIMISTIC): cv.boolean,
 }).extend(mqtt.MQTT_AVAILABILITY_SCHEMA.schema)
 
@@ -62,6 +65,7 @@ async def async_setup_platform(hass, config, async_add_devices,
         config.get(CONF_OPTIMISTIC),
         config.get(CONF_PAYLOAD_AVAILABLE),
         config.get(CONF_PAYLOAD_NOT_AVAILABLE),
+        config.get(CONF_UNIQUE_ID),
         value_template,
     )])
 
@@ -72,7 +76,8 @@ class MqttSwitch(MqttAvailability, SwitchDevice):
     def __init__(self, name, icon,
                  state_topic, command_topic, availability_topic,
                  qos, retain, payload_on, payload_off, optimistic,
-                 payload_available, payload_not_available, value_template):
+                 payload_available, payload_not_available,
+                 unique_id: Optional[str], value_template):
         """Initialize the MQTT switch."""
         super().__init__(availability_topic, qos, payload_available,
                          payload_not_available)
@@ -87,6 +92,7 @@ class MqttSwitch(MqttAvailability, SwitchDevice):
         self._payload_off = payload_off
         self._optimistic = optimistic
         self._template = value_template
+        self._unique_id = unique_id
 
     async def async_added_to_hass(self):
         """Subscribe to MQTT events."""
@@ -139,6 +145,11 @@ class MqttSwitch(MqttAvailability, SwitchDevice):
         """Return true if we do optimistic updates."""
         return self._optimistic
 
+    @property
+    def unique_id(self):
+        """Return a unique ID."""
+        return self._unique_id
+
     @property
     def icon(self):
         """Return the icon."""
diff --git a/tests/components/switch/test_mqtt.py b/tests/components/switch/test_mqtt.py
index b5e2a0b0395..24db0540012 100644
--- a/tests/components/switch/test_mqtt.py
+++ b/tests/components/switch/test_mqtt.py
@@ -248,3 +248,26 @@ class TestSwitchMQTT(unittest.TestCase):
 
         state = self.hass.states.get('switch.test')
         self.assertEqual(STATE_ON, state.state)
+
+    def test_unique_id(self):
+        """Test unique id option only creates one switch per unique_id."""
+        assert setup_component(self.hass, switch.DOMAIN, {
+            switch.DOMAIN: [{
+                'platform': 'mqtt',
+                'name': 'Test 1',
+                'state_topic': 'test-topic',
+                'command_topic': 'command-topic',
+                'unique_id': 'TOTALLY_UNIQUE'
+            }, {
+                'platform': 'mqtt',
+                'name': 'Test 2',
+                'state_topic': 'test-topic',
+                'command_topic': 'command-topic',
+                'unique_id': 'TOTALLY_UNIQUE'
+            }]
+        })
+
+        fire_mqtt_message(self.hass, 'test-topic', 'payload')
+        self.hass.block_till_done()
+        assert len(self.hass.states.async_entity_ids()) == 2
+        # all switches group is 1, unique id created is 1