Paula Abdul has signed on as the fourth and final judge of 'The X Factor,' the Hollywood Reporter has confirmed.

Sources say negotiations went down to the wire, due in part to her deal with CBS to appear on the dance-competition series 'Live to Dance.'

By joining 'The X Factor,' Abdul will be reunited with her 'American Idol' partner, Simon Cowell, along with judges Cheryl Cole and Antonio "L.A." Reid.

Meanwhile, PopCrush is reporting Pussycat Dolls singer Nicole Scherzinger will co-host 'The X Factor' with British TV personality Steve Jones.

[Hollywood Reporter]