"DeGeneres will sit alongside Simon Cowell, Randy Jackson and Kara DioGuardi and offer her own unique perspective to the contestants throughout the competition," People.com quoted Fox Television as saying in a statement.
"I'm going to have a day job and a night job," DeGeneres said at Wednesday's taping of the Thursday edition of "The Ellen DeGeneres Show." "This is so exciting for me."
Abdul announced last month she was leaving the singing competition series because she and the show's producers were not able to agree on a new contract. The new season of "Idol" is set to begin in January.
"I've been dying to tell everyone," DeGeneres said. "It's just been so hard to keep it a secret and we just finally got the OK and I'm so excited. It is going to be so much fun."