The Russian model, who is dating Cristiano Ronaldo, was revealed as the cover star during Monday night's Late Night With David Letterman.
Shayk was among ten models appearing on the CBS show when she discovered that a photoshoot she did with Bjorn Iooss in Hawaii had been selected for the coveted cover.
Before the giant billboard in Times Square featuring her image was unveiled, Letterman had quipped: "I don't even want to do this because I don't want to disappoint anyone... All my life I've disappointed women. It's kind of my thing!"
Other models who have appeared on the magazine's cover include Brooklyn Decker, Marisa Miller, Petra Nemcova, Tyra Banks, Elle MacPherson and Heidi Klum.
The swimsuit edition is available now.