The 'Never Say Never' hitmaker - who is dating Selena Gomez - invited 18-yer-old Cady Eimer to join him at the ceremony in Las Vegas last night (20.05.12) because he had been unable to attend her senior prom.
Cady, who hails from Virginia, had been asking the singer to be her date for the high school event for several years through her website, onelesslonelyprom.com but Justin had to decline the invite because of other commitments.
He said: ''I couldn't make it [to prom] so I said I need you to fly to the Billboard Awards and you can be my date.
''She's a big fan and I thought it would be fun.''
However, the 18-year-old singer forgot to give his date the traditional prom gift.
He admitted to People.com: ''I didn't get her a corsage.''
However, despite the lack of flowers, Cady - who was trending worldwide on social networking website twitter because of her invitation - had a wonderful time with her date.
She tweeted: ''@justinbieber @scooterbraun @kennyhamilton @allisonkaye thank you so much for an amazing night! I had the time of my life.
''Not gonna lie, I'm sad today's over. it was so much fun.''