Before doing so, make sure you’re logged in to the same Google Account used for both, and own the domain and the listing.
- On your computer, sign in to Google My Business.
- Click Website.
- Your Google domain will show. Click Connect.
- To confirm, click Connect again.
- If you want to see your website, click Visit site.
For More Information Please Refer: https://support.google.com/business/answer/7032844?hl=en