diff --git a/homeassistant/components/steamist/config_flow.py b/homeassistant/components/steamist/config_flow.py
index f182189a9c7..3d5fe000f35 100644
--- a/homeassistant/components/steamist/config_flow.py
+++ b/homeassistant/components/steamist/config_flow.py
@@ -170,6 +170,9 @@ class ConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
                 errors["base"] = "unknown"
             else:
                 if discovery := await async_discover_device(self.hass, host):
+                    await self.async_set_unique_id(
+                        dr.format_mac(discovery.mac), raise_on_progress=False
+                    )
                     return self._async_create_entry_from_device(discovery)
                 self._async_abort_entries_match({CONF_HOST: host})
                 return self.async_create_entry(title=host, data=user_input)
diff --git a/tests/components/steamist/test_config_flow.py b/tests/components/steamist/test_config_flow.py
index 63785b006e0..9664eb7323f 100644
--- a/tests/components/steamist/test_config_flow.py
+++ b/tests/components/steamist/test_config_flow.py
@@ -91,6 +91,7 @@ async def test_form_with_discovery(hass: HomeAssistant) -> None:
     assert result2["type"] == FlowResultType.CREATE_ENTRY
     assert result2["title"] == DEVICE_NAME
     assert result2["data"] == DEFAULT_ENTRY_DATA
+    assert result2["context"]["unique_id"] == FORMATTED_MAC_ADDRESS
     assert len(mock_setup_entry.mock_calls) == 1