According to a tweet from Heat magazine, the 22-year-old has been confirmed to join the panel of the show's eighth series, alongside Louis Walsh and previously-announced new judge Gary Barlow.
The tweet read: "BREAKING NEWS: Apparently Tulisa from N-Dubz has signed her X Factor deal! It's official, she's a judge!".
Former Destiny's Child star Kelly Rowland is also expected to be announced as part of the lineup before auditions begin in Birmingham on Wednesday.
A source told the News of the World: "We are happy with our female judges - Tulisa and Kelly.
"They will make up a strong panel with Louis Walsh and Gary Barlow. The auditions have to start on Wednesday because they have been scheduled to fit around the Take That tour."
The news of Tulisa's appointment comes after it was reported that Cheryl Cole will not return to The X Factor UK, after allegedly being axed from the US version of the show last week.
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