diff --git a/homeassistant/components/google_generative_ai_conversation/__init__.py b/homeassistant/components/google_generative_ai_conversation/__init__.py
index 3a7d160399d..4830e204654 100644
--- a/homeassistant/components/google_generative_ai_conversation/__init__.py
+++ b/homeassistant/components/google_generative_ai_conversation/__init__.py
@@ -267,6 +267,11 @@ async def async_migrate_integration(hass: HomeAssistant) -> None:
                 add_config_entry_id=parent_entry.entry_id,
             )
             if parent_entry.entry_id != entry.entry_id:
+                device_registry.async_update_device(
+                    device.id,
+                    add_config_subentry_id=subentry.subentry_id,
+                    add_config_entry_id=parent_entry.entry_id,
+                )
                 device_registry.async_update_device(
                     device.id,
                     remove_config_entry_id=entry.entry_id,