The two stars exchanged vows at the Parrot Cay resort in the Caribbean islands of Turks and Caicos, E! Online reported.
The surprise nuptials were attended by Garner's "Alias" co-star, Victor Garber, who looked on as the white-clad bride kissed her new husband following a sunset ceremony.
Garner and Affleck were believed to be planning to spend the Fourth of July weekend in Charleston, W.Va., at Garner's family home.
The couple have been dating since last year. They met on the set of 2003's "Daredevil," in which they starred as superhero lovers, Daredevil and Elektra.
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