Simon Cowell's doing something right!

The head honcho at The X Factor just signed on Demi Lovato as the fourth and final judge on the talent show, according to an E! News source.

Lovato will join Simon, L.A. Reid and Britney Spears at the judges' table when the show returns in September.

Fox won't comment on the news, neither will X Factor peeps, but reports claim Spears will get $15 million for a single season.

Cowell fired his frenemy Paula Abdul and Pussycat Doll Nicole Scherzinger in January, after the show's ratings were considerably below American Idol.