Gary, who has appeared on the judging panel for the past three years, has announced that he will leave the ITV1 programme after this series.
The Take That star's announcement comes a day after his friend, DJ and former TV presenter Chris Evans, let slip on Radio 2 that he is to bow out.
Chris had told listeners: "Apparently Gary Barlow is feeling the pressure ahead of the live shows.
"By the way, this will be Gary's last year on The X Factor... because he told me last week."
Tonight (12 October), during the first live show of the series, Gary confirmed Chris' comments about him leaving.
After his group Rough Copy had performed, Gary told them: "I've been here for three years and I'm so glad that for my last year on the show I get to mentor you guys."
Gary's subtle announcement was met with a smattering of boos from the audience.
All 12 finalists took to the stage to perform tonight, however following the new 'Flash Vote' twist, Shelley Smith was told she will definitely be in the bottom two sing-off tomorrow night.
Check out this year's 12 finalists in our gallery below:
Copyright: ITV Tom Dymond/Thames TV