Cheryl Fernandez-Versini is leaving the X Factor to focus on her music career.
The 32-year-old said in a statement: "I have had such an amazing experience being a judge on The X Factor.
"I have learnt so much and enjoyed nurturing talent but I've missed making music and am excited to be recording again.
"I want to thank everybody I have worked with along the way, especially Simon, who I love to bits. I hope the show continues to produce stars and I wish them all the best."
The show's boss, Simon Cowell, said: "Cheryl and myself spoke about this. I totally understand her commitment to making more records.
"She has been amazing on the show, and in the near future we will be working on other things together."
She has started working on a new album which is due for release later this year.
The former Girls Aloud singer joined the talent show in 2008 and two of her acts went on to win the show - Alexandra Burke and Joe McElderry.
She left the judging line-up in 2010 before returning again in 2014.
She mentored last year's runners-up, Reggie N Bollie, who finished behind 17-year-old Louisa Johnson.
Her exit follows the news that DJ Nick Grimshaw will not be returning as a judge.
The show's presenters, Caroline Flack and Olly Murs, also confirmed they would not return.
An X Factor spokesman said: " Cheryl has been a great judge and mentor during her time on the X Factor, from her early years of winning with two of her acts - Alexandra Burke and Joe McElderry - through to last year's series where she took Reggie N Bollie into the final.
"We'd like to thank Cheryl for her contribution to the show and wish her all the best with her return to music."
X Factor favourite Dermot O'Leary confirmed in March that he is returning "home" to the show, a year after he left the ITV talent series.
The 42-year-old said he is "excited to be back" as presenter.
O'Leary, who had been a mainstay of the show for eight years, left in 2015, saying it was "time for me to move on".
However, he has now said he is "really looking forward" to the forthcoming series.
"I'm very flattered to be asked back to the X Factor, and am currently dusting off my dancing shoes," he said.
"There is nothing more exciting than hosting live TV on a Saturday night. The show is naturally very close to my heart, after having hosted it for eight years."