Justin Bieber Performs 'Baby' At Kids' Choice Awards

Singer also fills in for an absent Ludacris by rapping the Atlanta MC's part.

Starry-eyed tweens and celebrities alike (we saw you, Tyra!) rocked out to [artist id="3187077"]Justin Bieber[/artist]'s single "Baby" during the 16-year-old's energetic performance Saturday (March 27) at the 23rd annual Nickelodeon Kids' Choice Awards.

Bieber kept his performance number a surprise for the fans, telling MTV News, "I do know what I'm performing, but I don't want to tell anyone."

Clad in his signature plaid shirt and Converse sneakers, Bieber bounded and bounced across the KCA stage, performing the My World 2.0 tune, even taking over collaborator Ludacris' rap portion to the delight of his gleeful fans.

The Canadian-born sensation was one of two singers to perform for the show, in addition to his crush, 22-year-old "Umbrella" singer Rihanna.

It's been a busy month for Bieber, who not only released his sophomore album on Tuesday, but recently announced his first headlining My World Tour, which kicks off June 23 in Hartford, Connecticut, and features guest performer Sean Kingston.

"It's going to be fun," Bieber told MTV News about the summer jaunt. "You can expect just to have a great time. It's somewhere that you can just have a blast. It's a place where hopefully you can relate to the songs and stuff. So hopefully you guys love it."

Bieber will also be hitting the broadcast airwaves next month, appearing as the musical guest on the April 10 Tina Fey-hosted episode of "Saturday Night Live."

"I'm really excited. I've watched it all my life," he said. "So it's amazing to be able to perform."