Hailee Steinfeld is here to prove that one-piece swimsuits can be super sexy. The "Rock Bottom" singer showed off her svelte physique in Miami over the weekend, and she looked incredible in an on-trend black bathing suit as she soaked up the sun with pals.

For her day at the beach, Steinfeld complemented her simple low-neck one-piece with a charm necklace, stacked bracelets, and oversize black sunglasses. The Pitch Perfect 2 star kept her long, wavy brunette hair down.

The gorgeous 19-year-old singer and actress was in Florida for the iHeart Radio Pool Party, where she performed with DNCE's Joe Jonas, but she made sure she got in some quality R&R. Steinfeld was spotted frolicking in the ocean, taking a stroll on the beach, and laying out beachside while eating a hamburger.

Steinfeld took to Instagram to share snaps from her performance with Jonas, and she definitely embraced the city's vibrant style. She took the stage in a breezy, pleated color-block dress.