He was scheduled to perform on "Shake It Up, Chicago!" and needed dancers to perform with him, choosing CeCe and Rocky after his manager rejected a handful of other hopefuls. His manager, Karen Thomas, tells CeCe and Rocky that he is 16-years-old and needs young dancers like them, but it was later revealed he is 24 and only said he was 16 to appeal to girls Rocky and CeCe's age. Rocky is very dejected by this, but relentlessly carries on loving him.
It was also revealed he is having a relationship with his manager after CeCe took a souvenir picture of Rocky in his hat, and in the background, Justin and Karen were kissing. Not knowing what to do, CeCe accidentally sent it to everyone on her contact list (after meaning to send it to her mom) and it ended up on the news, causing Justin to reveal the truth. He and Karen revealed that not only is she his manager, but she is his wife, too. He ended up thanking Rocky and CeCe for revealing it to the world, because now he could live a normal life like any 'young billionaire' instead of having to pretend.
It was stated by Tinka that he got discovered after posting videos of himself singing on the internet, like Justin Bieber.
Justin is revealed to be 24-years-old, not 16. ("Age It Up")
Justin likes to think of himself as a normal teen.