The new policy will take effect Nov. 11. Google said it will give users the ability to limit or even opt out completely from the ads, and users under the age of 18 will be excluded from the new program.
Google's online rival, Facebook, has long promoted the idea of using "likes" and recommendations from friends as a useful service and a powerful advertising tool. But Facebook has run into criticism and lawsuits over its use of recommendations, with privacy advocates and other critics complaining that the social network's users never intended to have their names or personal endorsements used in advertising campaigns.
Anticipating that criticism, Google took pains Friday to portray its new policy as user-friendly.
"Feedback from people you know can save you time and improve results for you and your friends across all Google services, including Search, Maps, Play and in advertising," the company said in a statement posted online.
But it added, "On Google, you are in control of what you share."
Facebook allows users to limit the use of their comments and endorsements - so they can only be seen by friends, for example. But it doesn't allow them to completely opt out of having recommendations shared in commercial messages. Facebook has also been criticized for using endorsements made by teens under 18.
Google has previously used individuals' endorsements in advertising on a more limited scale, such as when users click "(plus) 1," which is similar to Facebook's "like" button. But the new policy allows the use of comments and ratings.
"Recommendations from people you know can really help. So your friends, family and others may see your Profile name and photo, and content like the reviews you share or the ads you (plus) 1'd," the company said. "For example, your friends might see that you rated an album 4 stars on the band's Google Play page. And the (plus) 1 you gave your favorite local bakery could be included in an ad that the bakery runs through Google."
Google announced the change Friday in a revision to its terms of service but did not indicate when it might actually begin showing such advertising.