Fox and DioGuardi made the news official Friday following weeks of widespread speculation that her time on the show had run out.
"I felt like I won the lottery when I joined American Idol two years ago, but I feel like now is the best time to leave Idol," DioGuardi said in a statement. "I am very proud to have been associated with [the show] — it has truly been an amazing experience. I am grateful to Fox, FremantleMedia and 19 Entertainment, as well as the cast, crew and contestants, for all they have given to me. I look forward to my next challenge, and want to thank everyone who has supported me. All the best to everyone on Season 10!"
Her departure comes weeks after Ellen DeGeneres called it quits, and amid other big creative changes to Idol.
The changes include new judges to replace Simon Cowell, DeGeneres and DioGuardi, allowing competitors as young as 15, and the return of executive producer Nigel Lythgoe. Lythgoe said in April, before rejoining the show, "I would replace the entire judging panel... They don't have a great deal of chemistry at the moment."
On Aug. 19, Lythgoe promised a new lineup would be announced in three weeks. And while no deals for next season have been signed, Randy Jackson is reportedly a lock. The other reported frontrunners are Jennifer Lopez and Steven Tyler.
DioGuardi's exit — whether voluntary or not -- was expected. Soon after DeGeneres signed off in late July, trade publications said producers were not planning to ask DioGuardi to renew her contract; she had always been signed to one-year deals.
DioGuardi's dad, former congressman Joe DioGuardi, in mid-August said his daughter had not heard from anyone involved in the decision-making process as to whether she'd be asked back. But she had not then made her own feelings clear to her dad: "Would she want to do it another year? I think so. But she just got married and she'd like to have a family, so maybe this is a good opening for her, too," he said.
In making the announcement, Fox sent a news release full of praise from the show's creative team, thanking DioGuardi for her contributions to the show while bidding her a fond farewell.
Fox president of alternative entertainment Mike Darnell said he has "always been amazed by her eye for talent and her commitment to developing and mentoring artists." Idol executive producer Simon Fuller said while he would miss having her on the show, he looks forward to working with her in music for many years to come.
Executive producer Cecile Frot-Coutaz called her "one of the most proclaimed songwriters in the U.S." who "brought a wealth of experience and unique perspective." And Ken Warwick, also an executive producer, said "anyone who knows Kara knows that she brings an unbelievable amount of passion, creativity and humility to everything she does."
Are you sorry to see Kara leave?