Until now only Facebook members have been able to find profiles, but from this evening, non-members will be able to scour the site. Search engines such as Google and Yahoo! will feature the listings from next month.
Facebook has defended the move, stressing that privacy rules are not changing, and that its 39m users can easily opt out of the public search listing, or restrict the listing to only include their name and photograph.
A statement was published on the site's news page today in an attempt to allay any concerns.
"Starting today, we are making limited public search listings available to people who are not logged in to Facebook.
"We're not exposing any new information, and you have complete control over your public search listing. We think this will help more people connect and find value from Facebook without exposing any actual profile information or data."
The statement may have been an attempt to pre-empt criticism, which has previously been levelled at the site. Critics accused it of paving the way for stalkers after the introduction of a news feed last year, leading to the nickname 'stalkbook'.