The Vogue cover girl will serve as a judge and mentor on the upcoming U.S. competition, which will give undiscovered talent the chance to land a modelling job.
The catwalk queen is determined not to be upstaged by a new batch of beauties, and admits she has been eating egg whites and fruit so she can flaunt her trim figure on the small screen.
She says, "I eat very healthy. I didn't always, but I do now. Listen, I'm doing The Face now so for me... I know that TV is supposed to make you look bigger, so I'm very disciplined in this period!"
Campbell, who is also an executive producer on the show, admits she is surprised by how "gruelling" her new venture is.
She tells TV personality Joan Rivers, "It's hard work, Joan. I don't know how you do it and you've done it for many years!
"Television's hard work. It's not like we go and do the shoot and we leave. It's, like, many gruelling hours... (but) I am enjoying it. I would love girls to be empowered by the show so that they find things - whether they make it as a model or not - that implement in their life (to help with) self-esteem issues."
The Face is due to begin airing next year (13).