Abdul, who has been without a contract since her previous deal expired at the end of the past season, the show's eighth, said in a post Tuesday night she will not return for another season, the Los Angeles Times reported.
"I'll miss nurturing all the new talent, but most of all being a part of a show that I helped from day1 become an international phenomenon," Abdul wrote.
Auditions for the upcoming season are set for Thursday in Denver. Fox has already announced that Kara DioGuardi, who was added as a judge for the most recent season of "American Idol," would be returning.
Fox issued a joint statement with FremantleMedia North America and 19 Entertainment, which produce the show, saying they wish Abdul "the best."
"Paula Abdul has been 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," the statement said.