diff --git a/homeassistant/config_entries.py b/homeassistant/config_entries.py
index 6fb5595dac48..793e8be00456 100644
--- a/homeassistant/config_entries.py
+++ b/homeassistant/config_entries.py
@@ -817,13 +817,19 @@ class ConfigFlow(data_entry_flow.FlowHandler):
         raise data_entry_flow.UnknownHandler
 
     @callback
-    def _abort_if_unique_id_configured(self) -> None:
+    def _abort_if_unique_id_configured(self, updates: Dict[Any, Any] = None) -> None:
         """Abort if the unique ID is already configured."""
+        assert self.hass
         if self.unique_id is None:
             return
 
-        if self.unique_id in self._async_current_ids():
-            raise data_entry_flow.AbortFlow("already_configured")
+        for entry in self._async_current_entries():
+            if entry.unique_id == self.unique_id:
+                if updates is not None and not updates.items() <= entry.data.items():
+                    self.hass.config_entries.async_update_entry(
+                        entry, data={**entry.data, **updates}
+                    )
+                raise data_entry_flow.AbortFlow("already_configured")
 
     async def async_set_unique_id(
         self, unique_id: str, *, raise_on_progress: bool = True
diff --git a/tests/test_config_entries.py b/tests/test_config_entries.py
index d2519a495e26..da3fb7406949 100644
--- a/tests/test_config_entries.py
+++ b/tests/test_config_entries.py
@@ -1080,6 +1080,77 @@ async def test_unique_id_existing_entry(hass, manager):
     assert len(async_remove_entry.mock_calls) == 1
 
 
+async def test_unique_id_update_existing_entry(hass, manager):
+    """Test that we update an entry if there already is an entry with unique ID."""
+    hass.config.components.add("comp")
+    entry = MockConfigEntry(
+        domain="comp",
+        data={"additional": "data", "host": "0.0.0.0"},
+        unique_id="mock-unique-id",
+    )
+    entry.add_to_hass(hass)
+
+    mock_integration(
+        hass, MockModule("comp"),
+    )
+    mock_entity_platform(hass, "config_flow.comp", None)
+
+    class TestFlow(config_entries.ConfigFlow):
+
+        VERSION = 1
+
+        async def async_step_user(self, user_input=None):
+            await self.async_set_unique_id("mock-unique-id")
+            await self._abort_if_unique_id_configured(updates={"host": "1.1.1.1"})
+
+    with patch.dict(config_entries.HANDLERS, {"comp": TestFlow}):
+        result = await manager.flow.async_init(
+            "comp", context={"source": config_entries.SOURCE_USER}
+        )
+
+    assert result["type"] == "abort"
+    assert result["reason"] == "already_configured"
+    assert entry.data["host"] == "1.1.1.1"
+    assert entry.data["additional"] == "data"
+
+
+async def test_unique_id_not_update_existing_entry(hass, manager):
+    """Test that we do not update an entry if existing entry has the data."""
+    hass.config.components.add("comp")
+    entry = MockConfigEntry(
+        domain="comp",
+        data={"additional": "data", "host": "0.0.0.0"},
+        unique_id="mock-unique-id",
+    )
+    entry.add_to_hass(hass)
+
+    mock_integration(
+        hass, MockModule("comp"),
+    )
+    mock_entity_platform(hass, "config_flow.comp", None)
+
+    class TestFlow(config_entries.ConfigFlow):
+
+        VERSION = 1
+
+        async def async_step_user(self, user_input=None):
+            await self.async_set_unique_id("mock-unique-id")
+            await self._abort_if_unique_id_configured(updates={"host": "0.0.0.0"})
+
+    with patch.dict(config_entries.HANDLERS, {"comp": TestFlow}), patch(
+        "homeassistant.config_entries.ConfigEntries.async_update_entry"
+    ) as async_update_entry:
+        result = await manager.flow.async_init(
+            "comp", context={"source": config_entries.SOURCE_USER}
+        )
+
+    assert result["type"] == "abort"
+    assert result["reason"] == "already_configured"
+    assert entry.data["host"] == "0.0.0.0"
+    assert entry.data["additional"] == "data"
+    assert len(async_update_entry.mock_calls) == 0
+
+
 async def test_unique_id_in_progress(hass, manager):
     """Test that we abort if there is already a flow in progress with same unique id."""
     mock_integration(hass, MockModule("comp"))