Justin Bieber swept the American Music Awards in Los Angeles on Sunday night.

The 18-year-old Baby hitmaker fought off competition from Rihanna, Maroon 5, Drake and Katy Perry to win artist of the year.

Justin scored the first gong of the evening, beating out Flo Rida, Pitbull and Usher to be named favourite pop/rock male artist.

Taking the stage, Justin thanked his mother, Pattie Mallette, who accompanied him on the red carpet in lieu of his supposed ex-girlfriend, Selena Gomez.

Justin also thanked his manager, his “beautiful fans” and “the haters”.

"I want to say this is for all the haters who that I was just here for one or two years. I feel like I'm going to be here for a very long time," he said.

Justin later in the evening beat out Maroon 5, Nicki Minaj and One Direction to win favourite pop/rock album for Believe and took the stage mid-show to perform his new hit single Beauty and a Beat with the rapper.

Justin's mentor Usher won favourite male soul/R&B artist. The Yeah! hitmaker opened the show with a remix of his hits including Numb, Climax and Can’t Stop, Won’t Stop, joined by a team of backing dancers.

Other awards went to Taylor Swift, who won for favourite female country music artist; Nicki Minaj for favourite rap/hip hop album (Pink Friday: Roman Reloaded); and Linkin Park for the alternative rock award.

Carly Rae Jepsen, Carrie Underwood, Christina Aguilera, Kelly Clarkson, Ke$ha, Linkin Park, No Doubt, Pitbull, Chris Brown, Swizz Beatz, Ludacris, Taylor Swift, The Wanted and Psy also performed.

The American Music Awards are televised by US network ABC.