diff --git a/homeassistant/helpers/device_registry.py b/homeassistant/helpers/device_registry.py
index 75fcda18eac..1f147a1884d 100644
--- a/homeassistant/helpers/device_registry.py
+++ b/homeassistant/helpers/device_registry.py
@@ -798,6 +798,7 @@ class DeviceRegistry(BaseRegistry[dict[str, list[dict[str, Any]]]]):
         model: str | None | UndefinedType = UNDEFINED,
         name_by_user: str | None | UndefinedType = UNDEFINED,
         name: str | None | UndefinedType = UNDEFINED,
+        new_connections: set[tuple[str, str]] | UndefinedType = UNDEFINED,
         new_identifiers: set[tuple[str, str]] | UndefinedType = UNDEFINED,
         remove_config_entry_id: str | UndefinedType = UNDEFINED,
         serial_number: str | None | UndefinedType = UNDEFINED,
@@ -813,6 +814,9 @@ class DeviceRegistry(BaseRegistry[dict[str, list[dict[str, Any]]]]):
 
         config_entries = old.config_entries
 
+        if merge_connections is not UNDEFINED and new_connections is not UNDEFINED:
+            raise HomeAssistantError("Cannot define both merge_connections and new_connections")
+
         if merge_identifiers is not UNDEFINED and new_identifiers is not UNDEFINED:
             raise HomeAssistantError
 
@@ -873,6 +877,10 @@ class DeviceRegistry(BaseRegistry[dict[str, list[dict[str, Any]]]]):
                 new_values[attr_name] = old_value | setvalue
                 old_values[attr_name] = old_value
 
+        if new_connections is not UNDEFINED:
+            new_values["connections"] = _normalize_connections(new_connections)
+            old_values["connections"] = old.connections
+
         if new_identifiers is not UNDEFINED:
             new_values["identifiers"] = new_identifiers
             old_values["identifiers"] = old.identifiers
diff --git a/tests/helpers/test_device_registry.py b/tests/helpers/test_device_registry.py
index e40b3ca0356..da99f176a3c 100644
--- a/tests/helpers/test_device_registry.py
+++ b/tests/helpers/test_device_registry.py
@@ -1257,6 +1257,7 @@ async def test_update(
         connections={(dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF")},
         identifiers={("hue", "456"), ("bla", "123")},
     )
+    new_connections = {(dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA")}
     new_identifiers = {("hue", "654"), ("bla", "321")}
     assert not entry.area_id
     assert not entry.labels
@@ -1275,6 +1276,7 @@ async def test_update(
             model="Test Model",
             name_by_user="Test Friendly Name",
             name="name",
+            new_connections=new_connections,
             new_identifiers=new_identifiers,
             serial_number="serial_no",
             suggested_area="suggested_area",
@@ -1288,7 +1290,7 @@ async def test_update(
         area_id="12345A",
         config_entries={mock_config_entry.entry_id},
         configuration_url="https://example.com/config",
-        connections={("mac", "12:34:56:ab:cd:ef")},
+        connections={("mac", "65:43:21:fe:dc:ba")},
         disabled_by=dr.DeviceEntryDisabler.USER,
         entry_type=dr.DeviceEntryType.SERVICE,
         hw_version="hw_version",
@@ -1319,6 +1321,12 @@ async def test_update(
         device_registry.async_get_device(
             connections={(dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF")}
         )
+        is None
+    )
+    assert (
+        device_registry.async_get_device(
+            connections={(dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA")}
+        )
         == updated_entry
     )
 
@@ -1336,6 +1344,7 @@ async def test_update(
         "device_id": entry.id,
         "changes": {
             "area_id": None,
+            "connections": {("mac", "12:34:56:ab:cd:ef")},
             "configuration_url": None,
             "disabled_by": None,
             "entry_type": None,
@@ -1352,6 +1361,105 @@ async def test_update(
             "via_device_id": None,
         },
     }
+    with pytest.raises(HomeAssistantError):
+        device_registry.async_update_device(
+            entry.id,
+            merge_connections=new_connections,
+            new_connections=new_connections,
+        )
+
+    with pytest.raises(HomeAssistantError):
+        device_registry.async_update_device(
+            entry.id,
+            merge_identifiers=new_identifiers,
+            new_identifiers=new_identifiers,
+        )
+
+
+@pytest.mark.parametrize(
+    ("initial_connections", "new_connections", "updated_connections"),
+    [
+        (  # No connection -> single connection
+            None,
+            {(dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF")},
+            {(dr.CONNECTION_NETWORK_MAC, "12:34:56:ab:cd:ef")},
+        ),
+        (  # No connection -> double connection
+            None,
+            {
+                (dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA"),
+                (dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF"),
+            },
+            {
+                (dr.CONNECTION_NETWORK_MAC, "65:43:21:fe:dc:ba"),
+                (dr.CONNECTION_NETWORK_MAC, "12:34:56:ab:cd:ef"),
+            },
+        ),
+        (  # single connection -> no connection
+            {(dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA")},
+            set(),
+            set(),
+        ),
+        (  # single connection -> single connection
+            {(dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA")},
+            {(dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF")},
+            {(dr.CONNECTION_NETWORK_MAC, "12:34:56:ab:cd:ef")},
+        ),
+        (  # single connection -> double connection
+            {(dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA")},
+            {
+                (dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA"),
+                (dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF"),
+            },
+            {
+                (dr.CONNECTION_NETWORK_MAC, "65:43:21:fe:dc:ba"),
+                (dr.CONNECTION_NETWORK_MAC, "12:34:56:ab:cd:ef"),
+            },
+        ),
+        (  # Double connection -> None
+            {
+                (dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF"),
+                (dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA"),
+            },
+            set(),
+            set(),
+        ),
+        (  # Double connection -> single connection
+            {
+                (dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA"),
+                (dr.CONNECTION_NETWORK_MAC, "12:34:56:AB:CD:EF"),
+            },
+            {(dr.CONNECTION_NETWORK_MAC, "65:43:21:FE:DC:BA")},
+            {(dr.CONNECTION_NETWORK_MAC, "65:43:21:fe:dc:ba")},
+        ),
+    ],
+)
+async def test_update_connection(
+    device_registry: dr.DeviceRegistry,
+    mock_config_entry: MockConfigEntry,
+    initial_connections: set[tuple[str, str]] | None,
+    new_connections: set[tuple[str, str]] | None,
+    updated_connections: set[tuple[str, str]] | None,
+) -> None:
+    """Verify that we can update some attributes of a device."""
+    entry = device_registry.async_get_or_create(
+        config_entry_id=mock_config_entry.entry_id,
+        connections=initial_connections,
+        identifiers={("hue", "456"), ("bla", "123")},
+    )
+
+    with patch.object(device_registry, "async_schedule_save") as mock_save:
+        updated_entry = device_registry.async_update_device(
+            entry.id,
+            new_connections=new_connections,
+        )
+
+    assert mock_save.call_count == 1
+    assert updated_entry != entry
+    assert updated_entry.connections == updated_connections
+    assert (
+        device_registry.async_get_device(identifiers={("bla", "123")}) == updated_entry
+    )
 
 
 async def test_update_remove_config_entries(