diff --git a/homeassistant/components/esphome/__init__.py b/homeassistant/components/esphome/__init__.py
index 2a885ed90ec..07b6d3071f6 100644
--- a/homeassistant/components/esphome/__init__.py
+++ b/homeassistant/components/esphome/__init__.py
@@ -333,6 +333,10 @@ async def async_setup_entry(  # noqa: C901
     if entry_data.device_info is not None and entry_data.device_info.name:
         cli.expected_name = entry_data.device_info.name
         reconnect_logic.name = entry_data.device_info.name
+        if entry.unique_id is None:
+            hass.config_entries.async_update_entry(
+                entry, unique_id=entry_data.device_info.name
+            )
 
     await reconnect_logic.start()
     entry_data.cleanup_callbacks.append(reconnect_logic.stop_callback)
diff --git a/homeassistant/components/esphome/config_flow.py b/homeassistant/components/esphome/config_flow.py
index 9fd12634e43..ea64fb7fb7f 100644
--- a/homeassistant/components/esphome/config_flow.py
+++ b/homeassistant/components/esphome/config_flow.py
@@ -331,6 +331,8 @@ class EsphomeFlowHandler(ConfigFlow, domain=DOMAIN):
             await cli.disconnect(force=True)
 
         self._name = self._device_info.name
+        await self.async_set_unique_id(self._name, raise_on_progress=False)
+        self._abort_if_unique_id_configured(updates={CONF_HOST: self._host})
 
         return None
 
diff --git a/tests/components/esphome/test_config_flow.py b/tests/components/esphome/test_config_flow.py
index 43e2f916082..a4d1f416868 100644
--- a/tests/components/esphome/test_config_flow.py
+++ b/tests/components/esphome/test_config_flow.py
@@ -81,6 +81,7 @@ async def test_user_connection_works(hass, mock_client, mock_zeroconf):
         CONF_NOISE_PSK: "",
     }
     assert result["title"] == "test"
+    assert result["result"].unique_id == "test"
 
     assert len(mock_client.connect.mock_calls) == 1
     assert len(mock_client.device_info.mock_calls) == 1
@@ -91,6 +92,35 @@ async def test_user_connection_works(hass, mock_client, mock_zeroconf):
     assert mock_client.noise_psk is None
 
 
+async def test_user_connection_updates_host(hass, mock_client, mock_zeroconf):
+    """Test setup up the same name updates the host."""
+    entry = MockConfigEntry(
+        domain=DOMAIN,
+        data={CONF_HOST: "test.local", CONF_PORT: 6053, CONF_PASSWORD: ""},
+        unique_id="test",
+    )
+    entry.add_to_hass(hass)
+    result = await hass.config_entries.flow.async_init(
+        "esphome",
+        context={"source": config_entries.SOURCE_USER},
+        data=None,
+    )
+
+    assert result["type"] == FlowResultType.FORM
+    assert result["step_id"] == "user"
+
+    mock_client.device_info = AsyncMock(return_value=MockDeviceInfo(False, "test"))
+
+    result = await hass.config_entries.flow.async_init(
+        "esphome",
+        context={"source": config_entries.SOURCE_USER},
+        data={CONF_HOST: "127.0.0.1", CONF_PORT: 80},
+    )
+    assert result["type"] == FlowResultType.ABORT
+    assert result["reason"] == "already_configured"
+    assert entry.data[CONF_HOST] == "127.0.0.1"
+
+
 async def test_user_resolve_error(hass, mock_client, mock_zeroconf):
     """Test user step with IP resolve error."""