It's the end of (another "X-Factor") era.
Lovato, 21, was on the show for two seasons, but is now turning her attention to her music. On Feb. 9, she'll kick off an arena tour in Vancouver.
"X-Factor" producer Simon Cowell thanked Lovato after she made her announcement on Twitter.
She and I have had our ups and downs but now consider her a true friend. The door will always be open. And thank you Demi. Simon.x
— Simon Cowell (@SimonCowell) December 19, 2013
On Monday, Cowell, who is also a judge on the show, announced that he expects the singing competition to return next season, but with some changes. Among them: The series may be cut back to one night. (He did not specify whether judges Kelly Rowland and Paulina Rubio will return.)
Meanwhile, Lovato has been diversifying her resume lately. Not only did she have a story arc on "Glee," but she also wrote a book, "Staying Strong: 365 Days a Year," and she appeared on the soundtrack for the film "Frozen."