There are more than 150,000 retailers that are currently supported in Google Manufacturer Center.
Google does not provide a list but you can always find out which retailers are supported by finding their products available on Google Shopping.
Watch our Google Manufacturer Center Webinar with Google.
Brian Roizen is the Cofounder and Chief Architect of Feedonomics, a full-service feed optimization platform that optimizes product data for hundreds of channels. He has been featured on numerous podcasts and eCommerce webinars, and regularly contributes to Search Engine Land and other industry-leading blogs. Brian graduated summa cum laude from UCLA with both a Bachelor’s and Master’s degree in Mechanical Engineering.