Responding to suggestions by X Factor judge Louis Walsh that she would return to the panel this series, the Girls Aloud star insisted on Twitter that the ITV contest was "now part of [her] past".
On persistent rumors of Cole's return, a close friend told The Mirror: "Enough is enough. Cheryl's no pushover and she does not want people to think she will go running back to X Factor after the way she was treated by Simon Cowell.
"She is a strong girl and is moving on. She was dumped from X Factor USA and she's made up her mind [that] she is not going back.
"She doesn't need to do the show. Cheryl is all about her music now," the insider continued. "She lives, sleeps and breathes her new album - it's her passion."
Meanwhile, an X Factor insider added that Cole's refusal to return - allegedly as a replacement for Kelly Rowland - had come as a major blow to show bosses.
"We had hoped that Cheryl was going to be the missing piece of the puzzle for 2012 - she could have guaranteed the series was the biggest ever," the source said.
"She is friends with Gary [Barlow], Louis and Tulisa [Contostavlos], so it could have been the perfect mix but now we are back to square one. She was top of the list for Simon and ITV, so we have to look again at our options and move quickly."
It has also been reported that Cowell was prepared to offer Cole £2.5m to judge The X Factor - more than double her original fee.