In addition to continuing to co-host Xtra Factor, the 33-year-old will present from backstage at the live shows, chatting with contestants before and after their performances.
Caroline told The Mirror: "I can't wait to help out Dermot O'Leary on The X Factor and share all the backstage antics with people at home. Live shows this year are going to be the best yet."
News of her appointment came following false rumours at the weekend she would be co-hosting the live shows with Dermot.
Dermot said of her new role: "It's a big family at The X Factor and I'm thrilled to have Caroline on board on the main show. She's my TV little sister and she'll be great."
Viewers saw judges Nicole Scherzinger, Gary Barlow, Louis Walsh and Sharon Osbourne choosing their acts for the live shows at the weekend, following a judges' houses round at glamorous locations LA, New York, St. Tropez and Antigua.
The live shows will kick off this weekend.
It's already been revealed the first live show will have an 80s theme and, in a new twist for 2013, a concept called the Flash Vote has been introduced.
Once all the twelve acts have performed, the phone lines will open to the public for just ten minutes. Viewers can vote to save and once the lines have closed, the two acts with the least number of votes will learn there and then they have to face a sing-off the following night.
Check out this year's top twelve for the live shows below:
Copyright: ITV Tom Dymond/Thames TV