While the actress has previously mentioned she wasn't an *NSYNC fan when she was younger, she dressed up as her former boy band husband, Justin Timberlake, to attend the annual Casamigos Halloween party on Friday night.
For the "Brought to You by Those Who Drink It" celebrations held at Casamigos co-founder Mike Meldman’s Beverly Hills home, Biel wore a teal metallic jumpsuit with white tennis shoes. She completed the look with a curly blonde wig and blue sunglasses. Timberlake, meanwhile, coordinated with his wife's '90s look by dressing up as a giant microphone.
And that's not all! Biel was joined by four others who dressed up as the rest of the *NSYNC members: JC Chasez, Chris Kirkpatrick, Joey Fatone and Lance Bass.
It was a fun night for Timberlake and Biel. An eyewitness tells ET the couple was seen in the home's backyard, dancing and holding on to each other, adding that they were "all over each other all night."
The two weren't the only celebs to go all out for the Halloween party. Lisa Rinna looked spectacular dressed as Jennifer Lopez in her iconic GRAMMYs Versace dress.
Casamigos co-founder Rande Gerber and wife Cindy Crawford opted for a fun '70s look, while Nina Dobrev channeled her inner Billie Eilish.
Patrick Schwarzenegger dressed as the International Man of Mystery, Austin Powers, with girlfriend Abby Champion being a sexy fembot.
The mansion was decked out in a psychedelic theme, with a number of custom neon features and graffiti backdrops displayed throughout the home. The entrance featured a dynamic pumpkin patch, complete with hundreds of hand painted neon pumpkins and black light visual effects. The guests were welcomed with a Casamigos ice shot, as well as treated to signature cocktails, including the Casa-delic, Magic Marg and Spicy Spirit.
During the night, partygoers munched on a variety of late-night bites on the back patio, including pizza, burgers, tacos, guacamole and chips and grilled cheese. There was also a photo booth station with a swing and D.J. group The Misshapes spun tunes all night.
Molly Sims and Scott Stuber, Gerard Butler, Laverne Cox, Paris Hilton, Eiza Gonzalez, Ryan Phillippe, Kaitlynn Carter, Linda Thompson and Dave Grohl, among others were also in attendance.