diff --git a/homeassistant/helpers/device_registry.py b/homeassistant/helpers/device_registry.py
index 96425b2ea93..cb009efeb07 100644
--- a/homeassistant/helpers/device_registry.py
+++ b/homeassistant/helpers/device_registry.py
@@ -11,7 +11,7 @@ import attr
 from homeassistant.backports.enum import StrEnum
 from homeassistant.const import EVENT_HOMEASSISTANT_STARTED
 from homeassistant.core import Event, HomeAssistant, callback
-from homeassistant.exceptions import RequiredParameterMissing
+from homeassistant.exceptions import HomeAssistantError, RequiredParameterMissing
 from homeassistant.loader import bind_hass
 import homeassistant.util.uuid as uuid_util
 
@@ -420,10 +420,14 @@ class DeviceRegistry:
         """Update device attributes."""
         old = self.devices[device_id]
 
-        changes: dict[str, Any] = {}
+        new_values: dict[str, Any] = {}  # Dict with new key/value pairs
+        old_values: dict[str, Any] = {}  # Dict with old key/value pairs
 
         config_entries = old.config_entries
 
+        if merge_identifiers is not UNDEFINED and new_identifiers is not UNDEFINED:
+            raise HomeAssistantError()
+
         if isinstance(disabled_by, str) and not isinstance(
             disabled_by, DeviceEntryDisabler
         ):
@@ -462,7 +466,8 @@ class DeviceRegistry:
             config_entries = config_entries - {remove_config_entry_id}
 
         if config_entries != old.config_entries:
-            changes["config_entries"] = config_entries
+            new_values["config_entries"] = config_entries
+            old_values["config_entries"] = old.config_entries
 
         for attr_name, setvalue in (
             ("connections", merge_connections),
@@ -471,10 +476,12 @@ class DeviceRegistry:
             old_value = getattr(old, attr_name)
             # If not undefined, check if `value` contains new items.
             if setvalue is not UNDEFINED and not setvalue.issubset(old_value):
-                changes[attr_name] = old_value | setvalue
+                new_values[attr_name] = old_value | setvalue
+                old_values[attr_name] = old_value
 
         if new_identifiers is not UNDEFINED:
-            changes["identifiers"] = new_identifiers
+            new_values["identifiers"] = new_identifiers
+            old_values["identifiers"] = old.identifiers
 
         for attr_name, value in (
             ("configuration_url", configuration_url),
@@ -491,25 +498,27 @@ class DeviceRegistry:
             ("via_device_id", via_device_id),
         ):
             if value is not UNDEFINED and value != getattr(old, attr_name):
-                changes[attr_name] = value
+                new_values[attr_name] = value
+                old_values[attr_name] = getattr(old, attr_name)
 
         if old.is_new:
-            changes["is_new"] = False
+            new_values["is_new"] = False
 
-        if not changes:
+        if not new_values:
             return old
 
-        new = attr.evolve(old, **changes)
+        new = attr.evolve(old, **new_values)
         self._update_device(old, new)
         self.async_schedule_save()
 
-        self.hass.bus.async_fire(
-            EVENT_DEVICE_REGISTRY_UPDATED,
-            {
-                "action": "create" if "is_new" in changes else "update",
-                "device_id": new.id,
-            },
-        )
+        data: dict[str, Any] = {
+            "action": "create" if old.is_new else "update",
+            "device_id": new.id,
+        }
+        if not old.is_new:
+            data["changes"] = old_values
+
+        self.hass.bus.async_fire(EVENT_DEVICE_REGISTRY_UPDATED, data)
 
         return new
 
diff --git a/tests/helpers/test_device_registry.py b/tests/helpers/test_device_registry.py
index a0949bad03c..4e4150fe504 100644
--- a/tests/helpers/test_device_registry.py
+++ b/tests/helpers/test_device_registry.py
@@ -96,8 +96,12 @@ async def test_get_or_create_returns_same_entry(
     assert len(update_events) == 2
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "update"
     assert update_events[1]["device_id"] == entry.id
+    assert update_events[1]["changes"] == {
+        "connections": {("mac", "12:34:56:ab:cd:ef")}
+    }
 
 
 async def test_requirement_for_identifier_or_connection(registry):
@@ -518,14 +522,19 @@ async def test_removing_config_entries(hass, registry, update_events):
     assert len(update_events) == 5
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "update"
     assert update_events[1]["device_id"] == entry2.id
+    assert update_events[1]["changes"] == {"config_entries": {"123"}}
     assert update_events[2]["action"] == "create"
     assert update_events[2]["device_id"] == entry3.id
+    assert "changes" not in update_events[2]
     assert update_events[3]["action"] == "update"
     assert update_events[3]["device_id"] == entry.id
+    assert update_events[3]["changes"] == {"config_entries": {"456", "123"}}
     assert update_events[4]["action"] == "remove"
     assert update_events[4]["device_id"] == entry3.id
+    assert "changes" not in update_events[4]
 
 
 async def test_deleted_device_removing_config_entries(hass, registry, update_events):
@@ -568,14 +577,19 @@ async def test_deleted_device_removing_config_entries(hass, registry, update_eve
     assert len(update_events) == 5
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "update"
     assert update_events[1]["device_id"] == entry2.id
+    assert update_events[1]["changes"] == {"config_entries": {"123"}}
     assert update_events[2]["action"] == "create"
     assert update_events[2]["device_id"] == entry3.id
+    assert "changes" not in update_events[2]["device_id"]
     assert update_events[3]["action"] == "remove"
     assert update_events[3]["device_id"] == entry.id
+    assert "changes" not in update_events[3]
     assert update_events[4]["action"] == "remove"
     assert update_events[4]["device_id"] == entry3.id
+    assert "changes" not in update_events[4]
 
     registry.async_clear_config_entry("123")
     assert len(registry.devices) == 0
@@ -892,7 +906,7 @@ async def test_format_mac(registry):
         assert list(invalid_mac_entry.connections)[0][1] == invalid
 
 
-async def test_update(registry):
+async def test_update(hass, registry, update_events):
     """Verify that we can update some attributes of a device."""
     entry = registry.async_get_or_create(
         config_entry_id="1234",
@@ -940,6 +954,24 @@ async def test_update(registry):
 
     assert registry.async_get(updated_entry.id) is not None
 
+    await hass.async_block_till_done()
+
+    assert len(update_events) == 2
+    assert update_events[0]["action"] == "create"
+    assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
+    assert update_events[1]["action"] == "update"
+    assert update_events[1]["device_id"] == entry.id
+    assert update_events[1]["changes"] == {
+        "area_id": None,
+        "disabled_by": None,
+        "identifiers": {("bla", "123"), ("hue", "456")},
+        "manufacturer": None,
+        "model": None,
+        "name_by_user": None,
+        "via_device_id": None,
+    }
+
 
 async def test_update_remove_config_entries(hass, registry, update_events):
     """Make sure we do not get duplicate entries."""
@@ -989,17 +1021,22 @@ async def test_update_remove_config_entries(hass, registry, update_events):
     assert len(update_events) == 5
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "update"
     assert update_events[1]["device_id"] == entry2.id
+    assert update_events[1]["changes"] == {"config_entries": {"123"}}
     assert update_events[2]["action"] == "create"
     assert update_events[2]["device_id"] == entry3.id
+    assert "changes" not in update_events[2]
     assert update_events[3]["action"] == "update"
     assert update_events[3]["device_id"] == entry.id
+    assert update_events[3]["changes"] == {"config_entries": {"456", "123"}}
     assert update_events[4]["action"] == "remove"
     assert update_events[4]["device_id"] == entry3.id
+    assert "changes" not in update_events[4]
 
 
-async def test_update_sw_version(registry):
+async def test_update_sw_version(hass, registry, update_events):
     """Verify that we can update software version of a device."""
     entry = registry.async_get_or_create(
         config_entry_id="1234",
@@ -1016,8 +1053,18 @@ async def test_update_sw_version(registry):
     assert updated_entry != entry
     assert updated_entry.sw_version == sw_version
 
+    await hass.async_block_till_done()
 
-async def test_update_hw_version(registry):
+    assert len(update_events) == 2
+    assert update_events[0]["action"] == "create"
+    assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
+    assert update_events[1]["action"] == "update"
+    assert update_events[1]["device_id"] == entry.id
+    assert update_events[1]["changes"] == {"sw_version": None}
+
+
+async def test_update_hw_version(hass, registry, update_events):
     """Verify that we can update hardware version of a device."""
     entry = registry.async_get_or_create(
         config_entry_id="1234",
@@ -1034,8 +1081,18 @@ async def test_update_hw_version(registry):
     assert updated_entry != entry
     assert updated_entry.hw_version == hw_version
 
+    await hass.async_block_till_done()
 
-async def test_update_suggested_area(registry, area_registry):
+    assert len(update_events) == 2
+    assert update_events[0]["action"] == "create"
+    assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
+    assert update_events[1]["action"] == "update"
+    assert update_events[1]["device_id"] == entry.id
+    assert update_events[1]["changes"] == {"hw_version": None}
+
+
+async def test_update_suggested_area(hass, registry, area_registry, update_events):
     """Verify that we can update the suggested area version of a device."""
     entry = registry.async_get_or_create(
         config_entry_id="1234",
@@ -1061,6 +1118,16 @@ async def test_update_suggested_area(registry, area_registry):
     assert updated_entry.area_id == pool_area.id
     assert len(area_registry.areas) == 1
 
+    await hass.async_block_till_done()
+
+    assert len(update_events) == 2
+    assert update_events[0]["action"] == "create"
+    assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
+    assert update_events[1]["action"] == "update"
+    assert update_events[1]["device_id"] == entry.id
+    assert update_events[1]["changes"] == {"area_id": None, "suggested_area": None}
+
 
 async def test_cleanup_device_registry(hass, registry):
     """Test cleanup works."""
@@ -1221,12 +1288,16 @@ async def test_restore_device(hass, registry, update_events):
     assert len(update_events) == 4
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "remove"
     assert update_events[1]["device_id"] == entry.id
+    assert "changes" not in update_events[1]
     assert update_events[2]["action"] == "create"
     assert update_events[2]["device_id"] == entry2.id
+    assert "changes" not in update_events[2]
     assert update_events[3]["action"] == "create"
     assert update_events[3]["device_id"] == entry3.id
+    assert "changes" not in update_events[3]
 
 
 async def test_restore_simple_device(hass, registry, update_events):
@@ -1266,12 +1337,16 @@ async def test_restore_simple_device(hass, registry, update_events):
     assert len(update_events) == 4
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "remove"
     assert update_events[1]["device_id"] == entry.id
+    assert "changes" not in update_events[1]
     assert update_events[2]["action"] == "create"
     assert update_events[2]["device_id"] == entry2.id
+    assert "changes" not in update_events[2]
     assert update_events[3]["action"] == "create"
     assert update_events[3]["device_id"] == entry3.id
+    assert "changes" not in update_events[3]
 
 
 async def test_restore_shared_device(hass, registry, update_events):
@@ -1358,18 +1433,31 @@ async def test_restore_shared_device(hass, registry, update_events):
     assert len(update_events) == 7
     assert update_events[0]["action"] == "create"
     assert update_events[0]["device_id"] == entry.id
+    assert "changes" not in update_events[0]
     assert update_events[1]["action"] == "update"
     assert update_events[1]["device_id"] == entry.id
+    assert update_events[1]["changes"] == {
+        "config_entries": {"123"},
+        "identifiers": {("entry_123", "0123")},
+    }
     assert update_events[2]["action"] == "remove"
     assert update_events[2]["device_id"] == entry.id
+    assert "changes" not in update_events[2]
     assert update_events[3]["action"] == "create"
     assert update_events[3]["device_id"] == entry.id
+    assert "changes" not in update_events[3]
     assert update_events[4]["action"] == "remove"
     assert update_events[4]["device_id"] == entry.id
+    assert "changes" not in update_events[4]
     assert update_events[5]["action"] == "create"
     assert update_events[5]["device_id"] == entry.id
-    assert update_events[1]["action"] == "update"
-    assert update_events[1]["device_id"] == entry.id
+    assert "changes" not in update_events[5]
+    assert update_events[6]["action"] == "update"
+    assert update_events[6]["device_id"] == entry.id
+    assert update_events[6]["changes"] == {
+        "config_entries": {"234"},
+        "identifiers": {("entry_234", "2345")},
+    }
 
 
 async def test_get_or_create_empty_then_set_default_values(hass, registry):