And the 16-year-old also went home with three other awards.
Justin, who became the youngest artist to ever win the AMA Artist of the Year award, got the most awards on the night including T-Mobile breakthrough artist of the year, favourite album and favourite male pop/rock artist.
He later tweeted: 'Holy c***!!!! What is going on!?!?!? I love EVERYONE!!!!
'Can't stop smiling!! WE DID IT!!! #NEVERSAYNEVER!!!!!!'
Pop sensation Rihanna, 22, opened the ceremony with a medley of hits, including new single What's My Name and Only Girl (In the World), before taking home the Soul/R&B Female Artist award.
Other performers on the night included Miley Cyrus, The Black Eyed Peas, Katy Perry and a pregnant Pink.