The idea: multi-fabric (multi-admin)
Each Matter controller (Google Home, Home Assistant, Apple Home) has its own "fabric". A Matter device can join several at once. The Home Assistant docs say the standard expects devices to support at least five fabrics. That means a lamp can be controlled by Google Home voice and a Home Assistant automation at the same time, locally, without either app owning it exclusively.
What you need
- A Matter-certified device (check for the Matter logo on the box, plus Wi-Fi or Thread).
- A Google hub (Nest speaker or display) as Google's Matter controller. For Thread devices, a Thread border router: HA's docs name the Nest Hub (2nd Gen) or Nest Wi-Fi Pro, or Home Assistant with its OpenThread Border Router app.
- Home Assistant with the Matter integration, which installs the official Matter server (on Home Assistant OS the default option works) and the latest Home Assistant Companion app on your phone.
- Keep IPv6 and mDNS working on the network the phone, hub and device share while you commission.
Per the Home Assistant docs:
- Make sure the device is working in Google Home and the Matter integration is set up in Home Assistant.
- Open the Home Assistant Companion app, go to Settings, Connectivity, Matter, and select Add device.
- Choose "Yes. It's already in use." then pick Google Home as the controller it is connected to, and follow the prompts. These steps use Google's own sharing prompt on the phone.
- Android tips from the docs: set the Companion app's location permission to "Allow all the time" during commissioning (background apps cannot read the Wi-Fi network name otherwise), and keep Google Play Services up to date.
- Name it, pick an area and finish. It now appears in both.
- In Home Assistant go to Settings, Connectivity, Matter, Devices, and select the device.
- Select Share device, then Share device again. No need to press anything on the device itself.
- In the Google Home app, add a Matter device and scan the QR code or enter the sharing code.
- Back in Home Assistant, the three-dot menu next to Share device lists Manage fabrics. Google should appear as "Google LLC".
- Names and rooms are normally kept separately in each app, so expect to rename and assign rooms in both.
- Removing the device from one controller does not remove it from the others. Use Manage fabrics to see who has it.
- If you factory reset a device, you need its QR or numeric setup code to commission it again. Keep a photo of it.
- Troubleshooting commissioning: check that a Thread border router exists on the same network, that the phone is close to the device, and that nothing blocks mDNS.
- Hubs that are Matter bridges (the HA docs name SwitchBot Hub 2, Aqara Hub M2, IKEA Dirigera and the Philips Hue Bridge) can expose their devices over Matter. Support varies by device type, so check each hub.
- For Philips Hue specifically, the HA docs say the native Hue integration offers many more features than Matter. Use Matter only when you want to hand Hue to another ecosystem.
- Home Assistant itself is a Matter controller, not a bridge: it cannot turn its own entities into Matter devices. A community project, the Home Assistant Matter Hub (RiDDiX fork, the original by t0bst4r is archived), can publish HA entities to Google Home, Alexa or Apple Home. It is community software and not Matter-certified, and its docs mention that some controllers only accept certified products. Google can be fussy with uncertified bridges, so test before depending on it and read the project's Google notes.
Question for the group: has anyone got a reliable multi-admin setup between Google Home and Home Assistant, and which devices or Thread border routers gave you trouble when sharing?