Cowell, who appeared on the judging panel between 2004-2010, will be seen giving Gary Barlow, Tulisa Contostavlos, Nicole Scherzinger and Louis Walsh the category that they will be mentoring over the remainder of the competition, after the contestants are narrowed down to the final 24 for the Judges’ Houses stage.
However, Cowell will only be seen delivering the news to each of the judges by phone, as he was filming The X Factor USA in Miami at the time.
It marks the first time Cowell has appeared on the show since his departure at the end of Series 7.
Last night’s Boot Camp episode saw over 70 acts culled before having a chance to sing, and one singer admitting to drinking during rehearsals.
The X Factor airs tonight at 7.30pm on ITV1.