Oh baby, baby! At iHeartRadio's 102.7 KIIS FM 2019 Jingle Ball on Friday, Billie Eilish paid tribute to none other than Britney Spears.
The 17-year-old singer wore a T-shirt and basketball shorts bearing the teen pop princess-turned-queen's likeness and name while performing at the event, which took place at the Forum in Inglewood, California. Gen-Zer Billie may be unfamiliar with Van Halen and Hilary Duff, but she knows and loves her Britney.
Perhaps Billie was simply returning the favor; In June, Britney posted on Instagram a video of herself dancing to Billie's "Bad Guy" while recreating her iconic "I'm a Slave 4 U" choreography from the 2001 MTV VMAs. The teen, who was born three months after that ceremony, commented, "OMG."
The Jingle Ball took place less than two weeks before Billie turns 18.
"I think it's really hard to navigate your teens and let alone navigate them as a person with a lot on their plate, with a lot to do. I think she's done it incredibly well and I'm just really proud of her," her brother, fellow musician, songwriter and producer Finneas O'Connell told E! News exclusively at the show. "I couldn't imagine a person turning 18 with more to be proud of."
Billie was also jointed at the event by her parents.
Other performers at KIIS-FM's Jingle Ball included Camila Cabello, Lizzo, Katy Perry, BTS with special guest Halsey, Sam Smith with special guest Normani and Louis Tomlinson, who replaced French Montana, who was recently hospitalized over concerns for his cardiovascular health, and is now on bed rest.
Lizzo stepped on stage wearing a pair of Daisy Dukes and a Santa-like coat.
"Close your eyes and say, 'I love you, me,'" she told the crowd. "Now look at me and say, 'I love you, Lizzo. Now this is a very no judgment crowd, no shame in your game. If you want to wiggle, I want to see you wiggle. If you want to laugh, then laugh. If you want to scream, scream!"
Later in her set, she told the crowd, "Thank you for accepting me for who I am. I want to let you know that if 20,000 people can accept me for who I am, the whole world can fall in love with you."
Celebrity attendees included Jamie Foxx, former Real Housewives of Orange County star and newly single Meghan King Edmonds—who attended with a girlfriend, Real Housewives of Beverly Hills stars Kyle Richards and Teddi Mellencamp, The Bachelorette alum Hannah Brown, The Bachelor alum Chris Soules, Bachelor Nation couples Caelynn Miller-Keyes and Dean Unglert and Ashley Iaconetti and Jared Haibon, plus Jason Priestley and Sarah Michelle Gellar.
The singer celebrates her 30th birthday onstage at Z100's Jingle Ball at Madison Square Garden in NYC.
The singer performs at Z100's Jingle Ball at Madison Square Garden in NYC.
The star performs at Z100's Jingle Ball at Madison Square Garden in NYC.
The married couple appears at Z100's Jingle Ball at Madison Square Garden in NYC.
The trio performs at Z100's Jingle Ball at Madison Square Garden in NYC.
The singer performs at Z100's Jingle Ball at Madison Square Garden in NYC.
The actress appears at Z100's Jingle Ball at Madison Square Garden in NYC.
The two appear together at Z100's Jingle Ball at Madison Square Garden in NYC.
The two perform at Z100's Jingle Ball at Madison Square Garden in NYC.
While rocking the red carpet, the "Good as Hell" singer sported scünci's limited edition "Kira Kira" crystal headband.
The singer performs at Z100's Jingle Ball at Madison Square Garden in NYC.
The two appear onstage at Z100's Jingle Ball at Madison Square Garden in NYC.
The model arrives at Z100's Jingle Ball at Madison Square Garden in NYC.
The singer performs at Z100's Jingle Ball at Madison Square Garden in NYC.
The model arrives at Z100's Jingle Ball at Madison Square Garden in NYC.
One word: iconique.
Take a bow! The "Good as Hell" singer looks effortlessly elegant in her larger-than-life ensemble.
2020 vibes.
The singer performs at 101.3 KDWB's Jingle Ball 2019, presented by Capital One, at Xcel Energy Center in St. Paul/Minneapolis, Minnesota.
The "Bad Guy" songstress looks like she's enjoying herself!
Behind-the-scenes moment!
The "Shameless" songstress is looking red hot, hot, hot.
The pop princess makes everyone green with envy with her bright lime ensemble.
The 17-year-old star waves to the crowd.
Pretty in pink! The pop star is all smiles after her epic performance.
The songwriter makes his way to event.
The singer pays tribute to Britney Spears.
The singer walks the carpet.
The singer takes the stage.
The singer rocks the crowd.
The singers showed each other much support; Lizzo bopped her head to BTS' music. Halsey danced, sang along and air-drummed to Katy's performance of "Firework." Louis danced backstage to Camila's performance of "Havana."