The 52-year-old won't be returning to the judging panel, but will instead be seen letting Gary Barlow, Louis Walsh, Tulisa Contostavlos and former Pussycat Doll Nicole Scherzinger know which category they will be mentoring this season, reported Daily Mail online.
Cowell called the quartet from Miami, where he is filming the US 'X Factor', to give them the news.
Barlow seemed delighted when he was told he will be in charge of the over-28s, with Contostavlos was equally positive about working with the girls.
While Walsh seemed pleased to be mentoring the groups, Scherzinger was somewhat surprised that she landed the boys category, but said that she was confident one of her contestants will win the competition.