The 16-year-old pop star and the 20-year-old model had been dating for nearly nine months.
The "Hannah Montana" star reportedly called things off last week, as she was preparing to head to Georgia to film her new movie, "The Last Song."
A source also confirmed the split to Us Weekly.
"They have been having trouble for a while," the source told Us Weekly. "It's been hard for a long time since Miley has been working so much and traveling a lot."
However, distance may not have been the only factor behind the breakup.
Miley has recently been spending time with her ex, Nick Jonas, which a friend of Justin's said put some strain on the relationship.
*So she's blowing Nick again?*