Us Weekly reported Thursday that Spears, who joined the Fox singing competition in May, will not have her contract renewed.
Spears, 31, whose most recent studio album "Femme Fatale" hit No. 1 on the Billboard Top 200 chart upon its release last year, was signed for a reported $15 million salary for the show's second season, which began in September and ended Dec. 20 with country singer Tate Stevens winning the $5 million record-contract prize.
A Fox spokeswoman said the network would have no statement. An "X Factor" spokeswoman said in a statement to Newsday, "No one has discussed next year's judging panel yet -- any reports otherwise are complete speculation."
Us said that Spears' perceived low level of energy and enthusiasm had made for lackluster television. Series creator Simon Cowell had said in October that Spears had proved "a lot better than everybody thought . . . She's very engaged . . . She has been, I think, a very, very good judge."
But in an interview with E! in mid-December, he conceded, "I don't know yet, to be honest with you," when asked if Spears would be returning. "I haven't had the conversation with her whether she'd want to, what other commitments she's got." When asked if he would like her back, he answered, "Yeah, I think I do, yeah."