Kate Upton didn't quite step out in her birthday suit -- but she came close.
The supermodel -- who turns 24 on Friday -- had an early birthday celebration, organized and hosted by CR Fashion Book editor in chief Carine Roitfeld, at The Blond at 11 Howard Hotel in New York City on Wednesday night.
The Sports Illustrated Swimsuit cover girl bared her butt in a thong bodysuit that she wore under a sheer, star-embellished dress. While posing with her fiancé, 33-year-old MLB pro Justin Verlander, Upton got cheeky with photographers, flashing her bum.
Upton appeared to thoroughly enjoy her birthday celebration, which included cake, tequila shots, and truffle cheeseballs. "I'm so happy to have my friends and family with me today!" she captioned one of her fun Instagram snaps.
Bella Hadid and Nick Jonas also attended the soiree. The "Chains" singer even showed off the adorable photo booth pics he took with Upton.
Upton has lots to celebrate this year! Last month, ET confirmed that the model got engaged to Verlander just as she was flashing her engagement ring on the Met Gala red carpet. The two reportedly started dating on-and-off for three years after meeting on the set of a commercial for MLB 2K12.
"We're really happy right now and just continuing being happy," she told ET in January.
Check out her ring in the video below.