diff --git a/homeassistant/components/rachio/config_flow.py b/homeassistant/components/rachio/config_flow.py
index 2f5835ad614..df9ead463f7 100644
--- a/homeassistant/components/rachio/config_flow.py
+++ b/homeassistant/components/rachio/config_flow.py
@@ -89,6 +89,10 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
             # they already have one configured as they can always
             # add a new one via "+"
             return self.async_abort(reason="already_configured")
+        properties = {
+            key.lower(): value for (key, value) in homekit_info["properties"].items()
+        }
+        await self.async_set_unique_id(properties["id"])
         return await self.async_step_user()
 
     async def async_step_import(self, user_input):
diff --git a/tests/components/rachio/test_config_flow.py b/tests/components/rachio/test_config_flow.py
index 57575fe5501..cadc346e403 100644
--- a/tests/components/rachio/test_config_flow.py
+++ b/tests/components/rachio/test_config_flow.py
@@ -111,16 +111,26 @@ async def test_form_homekit(hass):
     await setup.async_setup_component(hass, "persistent_notification", {})
 
     result = await hass.config_entries.flow.async_init(
-        DOMAIN, context={"source": "homekit"}
+        DOMAIN,
+        context={"source": "homekit"},
+        data={"properties": {"id": "AA:BB:CC:DD:EE:FF"}},
     )
     assert result["type"] == "form"
     assert result["errors"] == {}
+    flow = next(
+        flow
+        for flow in hass.config_entries.flow.async_progress()
+        if flow["flow_id"] == result["flow_id"]
+    )
+    assert flow["context"]["unique_id"] == "AA:BB:CC:DD:EE:FF"
 
     entry = MockConfigEntry(domain=DOMAIN, data={CONF_API_KEY: "api_key"})
     entry.add_to_hass(hass)
 
     result = await hass.config_entries.flow.async_init(
-        DOMAIN, context={"source": "homekit"}
+        DOMAIN,
+        context={"source": "homekit"},
+        data={"properties": {"id": "AA:BB:CC:DD:EE:FF"}},
     )
     assert result["type"] == "abort"
     assert result["reason"] == "already_configured"