US rapper Joey Bada$$ has been charged with assault after allegedly breaking a security guard's nose at the Falls Festival near Byron Bay in New South Wales.

The 19-year-old was about to go on stage on the closing night of the festival, on Friday, when he was stopped by a security guard checking his credentials.

Police have alleged the rapper then punched the security guard in the face before going on stage to perform.

The guard, 20, allegedly told police he thought Bada$$ was an unauthorised person.

Paramedics treated the guard for a broken nose and other facial injuries at the scene before he was taken to hospital.

The rapper was arrested by police after the show finished and taken to Byron Bay police station, where he spent the night in custody.

Bada$$, whose real name is Jo-Vaughn Virginie Scott, was charged with assault occasioning actual bodily harm.

He appeared in Lismore Local Court on Saturday and was granted bail.

He was ordered to face court again on March 19.

The Brooklyn rapper is currently touring Australia promoting his debut studio album B4.Da.$$, and is due to perform in Sydney and Melbourne this week.

The Falls Music and Arts Festival was held over the new year at three locations: Lorne in Victoria, Marion Bay in Tasmania and Byron Bay in New South Wales.