The 32-year-old reached back into her musical and sartorial repertoire for much of the performance, which included hits like "Toxic," "Everytime" and "Gimme More," and her notorious sparkly nude bodysuit.
Celebs like Katy Perry, Selena Gomez, Sia and Adam Lambert attended the event, while friends Miley Cyrus and Mario Lopez were on hand for brief appearances. Cyrus, who was doing "a lot of grinding" from her seat at the front of the stage, got close to one of the backup dancers. When it was "time to find a hottie," Spears pulled Lopez onstage to don a harness and crawl around.
"Dreams do come true!" Cyrus captioned an Instagram photo of Spears onstage.
Gomez Instagramed a photo of herself with songwriter Sia.
"The demographic of Vegas has been sliding in the last two years, much younger and the emphasis now is not so much on gaming," he said. "When you look at the landscape of pop stars, pop princesses, pop queens, there's nobody other than Britney who has the depth of a career and the number of albums. She has a huge repertoire to go to."