Confirming the tie-up this afternoon, Reuters said financial terms of the deal were not disclosed, though earlier reports indicated the partnership would last two years. Google will also supply search functionality to the site later this year.
The Mountain View, California, search giant already provides search and advertising to MySpace, the social networking leader.
Friendster kicked off the phenomenon when it launched in 2002, but has since become a fringer player, with almost half of its users originating in southeast Asia.
Nevertheless, the deal will come as a blow to Yahoo!, which last month rolled out its Panama ad platform with greater contextual advertising functionality.
"As a top-25 global web brand with 19m monthly unique visitors and 6bn page views per month, this agreement with Google allows Friendster to leverage the best industry platform to monetize our high-growth business," said Friendster business development VP Aaron Barnes in a statement.