Now, in order to use Google Assistant, you need to unlock your phone. Google Assistant, by default, does not work when the screen is turned off. This implies that saying “Ok Google” or “Hey Google” will not unlock your phone.
However, if security isn’t your priority and you would like to keep your Google Assistant on at all times, i.e. even when the screen is turned off.
1. Open Settings on your phone then tap on the Google option.
2. In here, click on Account Services.
3. Followed by the Search, Assistant, and Voice tab.
4. Next, click on the Voice option.
5. Under the Hey Google tab you will find the Voice Match option. Click on it.
6. Now, if you find the option to Unlock with voice match, then toggle on the switch next to it.
Once you enable this setting, you will be able to use Google Assistant when the screen is off. You can trigger Google Assistant by saying “Ok Google” or “Hey Google” as your phone will always be listening to you, even if the phone is locked.