If not, she's potentially blown a hole in TV's top-rated show - and rejected an eight-figure deal that represented a 30 percent raise, according to a person familiar with the talks. The person, lacking authority to speak publicly, asked not to be identified.
Abdul dropped her online bombshell Tuesday evening, right before season-nine auditions begin Friday in Denver. That has the whiff of a pressure tactic on Abdul's part, although boycotting the early auditions that skip from city to city might have been a less dramatic way to negotiate.
Her tweets, however, seemed to have an air of finality.
"With sadness in my heart, I've decided not to return" to Fox's singing contest, Abdul said on her Twitter account. "I'll miss nurturing all the new talent, but most of all being a part of a show that I helped from day 1 become an international phenomenon."
There was a sense of closure, too, in a statement from Fox and producers FremantleMedia North America and 19 Entertainment.
The companies said Abdul was "an important part of the 'American Idol' family over the last eight seasons and we are saddened that she has decided not to return to the show."
They said she was "a tremendous talent" and wished her the best.
Abdul's banter and bickering with acerbic fellow judge Simon Cowell was as regular an "Idol" fixture as off-key contestants. So was her shimmying behind the judges' table when contestants sang uptempo songs.
Earlier this year, Fox entertainment president Kevin Reilly called Abdul "an integral part of the show."
Her announcement came the day after Fox said that Kara DioGuardi would return for a second season on the "American Idol" judging panel.
The addition of Grammy-nominated songwriter DioGuardi last year raised questions about Abdul's future on the show, which was based on the British series "Pop Idol."
Cowell, DioGuardi and Randy Jackson are signed through season nine. Ryan Seacrest just agreed to a new deal, reportedly worth $45 million, that keeps him on as "Idol" host through 2012 and provides the opportunity for new entertainment ventures.
Despite a decline in its ratings, "American Idol" remains the No. 1-rated show and a money machine for Fox, its producers and for the record labels and singers like Carrie Underwood that have benefited from its star-making power. Removing any part of a familiar and winning TV formula can be risky and makes the show's future an open question.
In July, Abdul told The Associated Press that she had been invited to stay with "Idol" as long as the show lasted and that she was optimistic that she'd be able to negotiate a new contract.
But the 47-year-old singer-dancer said the invitation to come back was subject to agreement on the details of a new deal.
Abdul began working with a new manager, David Sonenberg, in recent weeks, and he said last month that prospects for a deal looked dim.
"What I want to say most, is how much I appreciate the undying support and enormous love that you have showered upon me," Abdul said to followers on Twitter in making her announcement.
A onetime-Los Angeles Lakers cheerleader, Abdul became an award-winning choreographer and singer, didn't indicate her post-"Idol" career plans in her tweet.
DioGuardi didn't slip smoothly into her new job. She endured eye rolls from Cowell over her comments and criticism of her judging abilities and long-winded, earnest style from viewers. She admitted to suffering nerves and worrying about fitting in.
But DioGuardi provided one of the season's highlights: Her feud with Katrina "Bikini Girl" Darrell during the audition rounds, when the judge - a talented singer in her own right - told the scantily clad wannabe to bring a stripper pole next time.
Abdul, whom contestants regularly lauded for being warm and supportive, was unlikely to make such a cutting remark.
But she brought her own measure of interest to "Idol." She appeared on camera with several maladies, including a manicure-induced infection and injuries sustained tripping over her dog. Abdul could be meandering in her remarks and was at times inordinately giggly.
In 2005, an ex-contestant claimed he and Abdul had an affair in 2003, which Abdul denied. Fox, which said it investigated the man's claims, stood by her.
"American Idol" starts its ninth season in January.