The pop singer and West End star appeared on Popstars in 2001, where he failed to make the final lineup of Hear'Say, and Pop Idol in 2002, when he finished third behind Gareth Gates and Will Young.
Campbell's latest musical venture is Popstar To Operastar, which will feature him competing with seven other singers learning the art of opera.
Speaking about the show, he told ITV: "I'd never have thought that the opportunity would arise to train with the world's greatest opera singers. It's an incredible privilege. I feel very humbled by it."
He joked: "I have had two opportunities before where I have auditioned on national television. Both times I lost. Third time lucky... I really don't want to lose this one!"
Popstar To Operastar airs tonight at 9pm on ITV1.