The "Umbrella" singer's breasts and tattooed midsection were easily visible through the sheep black top.
The Barbadian beauty, 27, rounded out the stylish outfit with silk pants and black Louboutin heels.
The Caribbean Queen hosted the celeb-laden bash, which was attended by stars such as Justin Bieber, Selena Gomez and Jennifer Lawrence.
The "You Da One" singer's light auburn mane was pinned down by hair clips as she confidently strolled into the hopping venue.
The 5-foot-8 beauty stole the show hours before at the annual costume gala, in a dress with a giant furry yellow cape.
The eye-popping outfit immediately inspired thousands of social media punchlines and memes, with some comparing the brash yellow outfit to Sesame Street alum Big Bird, or an omelette.
The "Diamonds" singer's hands shine bright like a set of diamonds, for good reason, as her fingers and wrists were decked out in priceless jewels.
Fans and paps were out in full force on the hopping New York City evening, where RiRi was the belle of the ball.