diff --git a/homeassistant/components/flux/switch.py b/homeassistant/components/flux/switch.py
index 63f58ff64c4..fac31d445cc 100644
--- a/homeassistant/components/flux/switch.py
+++ b/homeassistant/components/flux/switch.py
@@ -50,6 +50,8 @@ from homeassistant.util.dt import as_local, utcnow as dt_utcnow
 
 _LOGGER = logging.getLogger(__name__)
 
+ATTR_UNIQUE_ID = "unique_id"
+
 CONF_START_TIME = "start_time"
 CONF_STOP_TIME = "stop_time"
 CONF_START_CT = "start_colortemp"
@@ -88,6 +90,7 @@ PLATFORM_SCHEMA = vol.Schema(
         ),
         vol.Optional(CONF_INTERVAL, default=30): cv.positive_int,
         vol.Optional(ATTR_TRANSITION, default=30): VALID_TRANSITION,
+        vol.Optional(ATTR_UNIQUE_ID): cv.string,
     }
 )
 
@@ -151,6 +154,7 @@ async def async_setup_platform(
     mode = config.get(CONF_MODE)
     interval = config.get(CONF_INTERVAL)
     transition = config.get(ATTR_TRANSITION)
+    unique_id = config.get(ATTR_UNIQUE_ID)
     flux = FluxSwitch(
         name,
         hass,
@@ -165,6 +169,7 @@ async def async_setup_platform(
         mode,
         interval,
         transition,
+        unique_id,
     )
     async_add_entities([flux])
 
@@ -194,6 +199,7 @@ class FluxSwitch(SwitchEntity, RestoreEntity):
         mode,
         interval,
         transition,
+        unique_id,
     ):
         """Initialize the Flux switch."""
         self._name = name
@@ -209,6 +215,7 @@ class FluxSwitch(SwitchEntity, RestoreEntity):
         self._mode = mode
         self._interval = interval
         self._transition = transition
+        self._attr_unique_id = unique_id
         self.unsub_tracker = None
 
     @property
diff --git a/tests/components/flux/test_switch.py b/tests/components/flux/test_switch.py
index baf568b79b4..ab85303584f 100644
--- a/tests/components/flux/test_switch.py
+++ b/tests/components/flux/test_switch.py
@@ -14,6 +14,7 @@ from homeassistant.const import (
     SUN_EVENT_SUNRISE,
 )
 from homeassistant.core import HomeAssistant, State
+from homeassistant.helpers import entity_registry as er
 from homeassistant.setup import async_setup_component
 import homeassistant.util.dt as dt_util
 
@@ -52,6 +53,31 @@ async def test_valid_config(hass: HomeAssistant) -> None:
     assert state.state == "off"
 
 
+async def test_unique_id(
+    hass: HomeAssistant, entity_registry: er.EntityRegistry
+) -> None:
+    """Test configuration with unique ID."""
+    assert await async_setup_component(
+        hass,
+        "switch",
+        {
+            "switch": {
+                "platform": "flux",
+                "name": "flux",
+                "lights": ["light.desk", "light.lamp"],
+                "unique_id": "zaphotbeeblebrox",
+            }
+        },
+    )
+    await hass.async_block_till_done()
+    state = hass.states.get("switch.flux")
+    assert state
+    assert state.state == "off"
+
+    assert len(entity_registry.entities) == 1
+    assert entity_registry.async_get_entity_id("switch", "flux", "zaphotbeeblebrox")
+
+
 async def test_restore_state_last_on(hass: HomeAssistant) -> None:
     """Test restoring state when the last state is on."""
     mock_restore_cache(hass, [State("switch.flux", "on")])