The 'Bad Guy' singer celebrated her big day with a huge, festive party, perfect for the holidays.
Happy birthday and a marry Christmas! Billie Eilish celebrated her 21st birthday over the weekend with big, Christmas-themed festivities.
The songstress -- who technically turned 21 on Sunday -- partied the night away on Saturday with some of her most famous friends, including her boyfriend, Jesse Rutherford.
Many in attendance shared videos from the event, including clips of her blowing out her birthday candles while rocking a red Christmas gown with white fur trim.
One of the celeb guests who posted a number of pics from the party was Lil Nas X, who wore an on-brand torso-baring ensemble and posed with other friends and celebs at the event.
The Montero artist snapped selfies with Dove Cameron, Avril Lavigne, and Eric Andre, among others, and was all smiles as he rang in Eilish's big b-day.
Saturday's big birthday bash came one day after she performed at a sold-out show in Inglewood, California, where her boyfriend surprised her with a birthday cake on stage to celebrate the special occasion.
Happy birthday to the seven-time GRAMMY winner!