Billie Eilish Celebrates Her 21st Birthday in a Santa Micro Minidress

Billie Eilish celebrated her 21st birthday with a star-packed bash at Sunset at EDITION in West Hollywood, decked out in a holiday festive Santa costume. The pop star fit right in with the ambience in the party room, decorated with glowing Christmas trees, a red sleigh mounted for photos, shimmering disco balls, and mistletoe hung from the ceiling. The dress code was merry to fit the theme, and Eilish even blew out candles on a three-tier candy cane cake.

Her outfit consisted of a red velvet minidress cinched at the waist with a black leather belt and a matching glitter-dusted cape that was finished with the same white fur trim. Eilish wore a pair of sheer nude tights and accessorized with candy cane hoop earrings and opera-length Santa gloves. In a video re-shared to her Instagram Story, Eilish is seen smooching boyfriend Jesse Rutherford after a toast, who wore a bright red cardigan over a white button-down shirt to coordinate with his beau.

The guest list included plenty of celebrities beyond the expected, such as Dove Cameron, who wore a winterscape patterned cropped sweater; Lil Nas X, who showed up in a Santa bolero and metallic red pants; Hailey Bieber, who made an elegant statement in an emerald dress with a tie-front bustier top; and Kylie Jenner, who sported a 1017 Alyx 9Sm one-shoulder latex dress.

To the surprise of her fans, Eilish also released a limited edition Twenty One T-Shirt on her store to mark the occasion, which reads "been a good girl for 21 years" on the front.

Ahead, see additional shots from Eilish's soirée, re-create her look, and purchase her apparel that is still available for preorder.