Cady Eimer, an 18-year-old high school student, accompanied the 'Boyfriend' musician to the ceremony in Las Vegas.
Eimer had originally asked Bieber to take her to her senior prom, but he was unable to attend because of his other commitments.
Instead, he asked Eimer if she would like to come to the Billboard Awards, where he took home the 'Top Social Artist' honour.
"I couldn't make it [to Eimer's prom] so I said I need you to fly to the Billboard Awards and you can be my date," Bieber told People. "She's a big fan and I thought it would be fun."
However, Bieber joked: "I didn't get her a corsage."
Bieber, who is currently dating Selena Gomez, also performed 'Boyfriend' at the Awards.
Photo gallery - Billboard Awards 2012:
Copyright: PA Images John Shearer/AP