Wearing her blonde tresses down in a natural wave, the 21-year-old caused quite a stir in a navy swimsuit in the beach photo.
However, Hailey's right breast remained fully out of the one-piece, thanks to its plunging and asymmetric design.
But, undeterred, the Californian happily cupped her assets, meaning only her ample cleavage was on show.
Many complimented the stunner, with two users cheekily replying: "I wish you didn't have your hand there," and: "What a great photo! xoxo."
Hailey had earlier uploaded a video of her working on the images, and it's safe to say, it left little to the imagination.
"I'm backkkk! So excited to be back for my 3rd year in @si_swimsuit. Can’t wait to see everyone at VIBES on the 17th and 18th in Houston," she added.