The 'R.I.P.' singer will join the panel for tomorrow's (May 28) auditions in London, as had previously been rumoured.
"Or-some news! We can officially reveal that Brit babe and RIP singer Rita Ora will be guest Judging tomorrow in London. #GuestJudgesRule," the X Factor Twitter account confirmed.
Ora follows Geri Halliwell and former winner Leona Lewis, who guest judged in Liverpool and London respectively.
X Factor bosses are still searching for a permanent replacement for Kelly Rowland, who confirmed her exit in April.
Simon Cowell reportedly wants Ora to join the panel full-time, while current judges Louis Walsh, Tulisa Contostavlos and Gary Barlow have called for Sharon Osbourne to return.
A source close to Ora said that the job is "hers to lose" after she impressed producers during meetings.
Mel B and Tinie Tempah are also rumoured to have signed up to guest judge The X Factor.
Photo gallery - The X Factor auditions in Liverpool:
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