New mom Kylie Jenner's ready to show off her post-baby bod ... and what a bod it is!

Jenner stepped out in New York Saturday night in a shockingly-Spandex Alexander Wang look, showcasing her flat stomach, large chest and skinny legs. The voluptuous 20-year-old, who gave birth to daughter Stormi Webster with baby daddy Travis Scott just three months ago, proved she's got the Kardashian genes as she strutted her stuff in a belly-baring crop top and leather parachute pants earlier in the night for dinner at Nobu with sis Kendall.

Kylie's in town ahead of the Met Costume Institute Gala set for Monday. This year's theme should be interesting -- and perhaps a bit Madonna-esque ... "Heavenly Bodies: Fashion and the Catholic Imagination." We can't wait to see how Kylie and other celebs interpret that!