Swift lit up the stage with her overwhelmingly joyous new single, which she performed amid a veritable pastel wonderland that beautifully mirrored the technicolor glory of her song's stunning music video.
Kicking the number off with a pink-clad drum corps and marching band, Swift took the stage in a shimmering, rainbow fringe-colored outfit, and danced around with a bunch of suit-wearing back-up dancers.
Swift was pitch perfect for her performance of the super cute single, and even changed one key lyric to celebrate the awards show, switching the line, "Spelling is fun" to "Vegas is fun" for the occasion.
As Swift and Urie ended the song while floating above the audience in a rain of glitter, fans couldn't get enough as they cheered for the vibrant performance.
Swift's performance at the MGM Grand Garden Arena in Las Vegas marked the first live, televised performance of the catchy new song, and was the singer's first return to the BBMAs stage since 2013, when she performed her single, "22," off her album, Red.
Before performing, Swift walked the red carpet rocking a stunning, ruffled purple Raisa & Vanessa dress which she paired with silver Casadei heels and earrings by Stefere Jewelry and Graziela Gems.
Swift was one of several A-listers who are slated to perform at this year's star-studded show, including BTS, Paula Abdul, Jonas Brothers, Madonna, Khalid, Halsey and Mariah Carey, who will be honored with this year's ICON Award.
Before "ME!" and its wild, rainbow-colored, magically surreal video were released into the world, Swift explained the song's meaning and message to Good Morning America's Robin Roberts.
"[It's] about embracing your individuality," she said. "With a pop song, we have the ability to get a melody stuck in people's heads. I just want it to be one that makes them feel better about themselves."