Bieber and a few friends rolled up unannounced at Chatsworth Charter High School's prom Saturday night.
According to the school, his entourage pushed past the school's security to gain access to the dance floor.
It took a few seconds for the teens to realize the pop star was dancing among them. When they did, the crowd went wild!
The 21-year-old singer was only there for three or four minutes, but students immediately took to social media, calling it the best prom ever.