Fans have quickly taken the band to task for ignoring their roots as a hard rock act.
"Heavy? I didn't know this was opposite day," wrote one YouTube viewer.
"This is not just a bad song - this is a disgrace to what was once my favourite band.," wrote another.
Fans quickly took to Twitter complaining about the band's new sound, comparing Heavy to a Taylor Swift ballad.
There's more bad news for fans: Mike Shonoda explained to Billboard that the single perfectly represents the band's new album.
"One of the reasons why we chose Heavy as the first single is because it is really the core sound of the album," Shinoda said.
"This wasn't a scenario where the whole album sounds one way and the single sounds different. This is how the album sounds. So we wanted to go out with a song like that, where everybody can get a sense of the direction of this body of work."
The album art for One More Light has also been revealed, featured a group of children playing in the surf.
