Christopher Polk/Getty Images Happy birthday, Brit!
Britney Spears turned 35 Friday and received a birthday surprise at KIIS-FM's iHeartRadio Jingle Ball 2016 concert at Staples Center in Los Angeles, where she performed nine songs, including "Toxic," "Stronger" and "I'm a Slave 4 U" before closing her set with "Slumber Party" with special guest Tinashe.
"Guess what? It's my birthday. You guys ready for a slumber party?" Britney told the crowd. "Everybody give it up for Tinashe."
"Give it up for this legend!" Tinashe told the crowd after they were finished.
Ryan Seacrest then came out on stage and led the audience to sing "Happy Birthday" to Spears.
A three-tier cake with black fondant, pink frosting, pink roses and sparkling embellishments, including a large "B" topper, from Los Angeles bakery Sweet Red Peach, was then brought out for her as the words "Happy Birthday Britney" flashed on a big screen.
"Awwww thank you so much!" Spears said.
Other performers included Fifth Harmony, Alessia Cara, Bruno Mars, Diplo, Meghan Trainor and Justin Bieber, who closed out the show.
Celebs spotted in the crowd included Lance Bass and husband Michael Turchin, Grey's Anatomy actress Camilla Luddington, Bachelor in Paradise season three couple Josh Murray and Amanda Stanton, their co-stars Nick Viall, Jared Haibon and twins Emily Ferguson and Haley Ferguson and Dancing with the Stars pro Witney Carson.