The deal was revealed in a blog last night by Friendfeed founder Bret Taylor, who stated that the firm 'accepts Facebook friend request'.
Terms of the deal have not been disclosed, but it could see the Facebook's 250m users benefit from its FriendFeed's ability to share content in real time.
The acquisition of FriendFeed follows Facebook's failed attempt last year to buy hot microblogging service Twitter.
FriendFeed has been described as a potential rival to Twitter in its ability to conduct real-time search, an area where Facebook has been seeking to expand.
FriendFeed sells itself as a service that makes it easy to share information with friends online.
It works as an instant aggregator of information from other services such as Facebook, Twitter and photo-sharing site Flickr.
Users get a customised feed of updates and contents put on the web from friends.
Announcing the sale to Facebook, Mr Taylor said: 'We've always been great admirers of Facebook and our companies share a common vision.
'Now we have the opportunity to bring many of the innovations we've developed at FriendFeed to Facebook's 250m users.'
Chris Cox, vice president of products at Facebook, said that both firms were working to help people better connect with each other.
He said: 'I think both companies start with the premise that the most valuable information in the world is the one that comes from the people you care about.
'Building technologies that leverage those relationships everywhere you go is where we're both starting from.'
