The 19-year-old pop star has been teasing about the song since June. Per its description, the track is thought to be about Bieber's ex-girlfriend Selena Gomez.
"It's a song for people going through a heartbreak -- like I was when I wrote it," the singer wrote. "It means so much to me to be able to share what I was, and still am going through, with my fans. I'm very proud of this song and I hope it give my fans some insight into my heart."
If the description isn't enough prove that the song is about Gomez, here's an Istagram picture of Bieber with his ex, that he posted in early July captioned "#heartbreaker."
According to Billboard, Bieber's "Music Mondays" will feature one new song every week for 10 straight weeks.