The 48-year-old star joins Simon Cowell, L.A. Reid and Cheryl Cole on the panel of the pop star search show and admits she "couldn't be happier" to be working alongside 51-year-old music mogul Simon once again after the pair originally appeared together on American Idol.
She said: "I am excited beyond words to be a part of The X Factor. I couldn't be happier to bring my love for cultivating talent and performance to such a wildly anticipated show.
"I'm looking forward to being back with the FOX/FremantleMedia family and know that it will be an extraordinary journey - we're going to have a blast. I'm also delighted and grateful to be sitting next to Simon again... but you might want to check back with me in a week or two!"
Never be the same without Paula
Cowell - who began filming for The X Factor on May 8 - conceded the judging panel "would never have been the same" without Paula Abdul.
He added: "This show would never have been the same without Paula and I can't believe I am saying this, but I have missed her a lot, and I am thrilled she's on the show."
Meanwhile, Cheryl Cole is hoping Stateside fans will "embrace" her regional dialect, despite there being concerns American audiences won't understand her strong North East English accent.
The Fight for This Love singer - who is from Newcastle - said: "I'm hoping people are going to embrace it. I'm not worried about my accent. It's going to be interesting. I hear a lot of accents here too.
"I'm sure there will be words or phrases where people are like, 'Excuse me?'"