Finally Official: Khloe Kardashian & Mario Lopez are the X Factor Hosts

It's official ... Khloe Kardashian and Mario Lopez will be the new co-hosts of "X Factor" ... TMZ has confirmed with sources connected to the show.

We broke the story ... Khloe and Mario had been thiiiiiiis close to a deal for months ... but now we've confirmed they've both signed on the dotted line ... it's a done deal.

We're told the duo's salaries will add millions to the budget -- on top of an already enormous talent budget.

"I've always wanted to do hosting or talk-show hosting, so it's definitely something that I would love to do and would be honored to do," Kardashian told E! News in August. "To be on such a huge show like that with those judges, I would have so much fun doing that." Kardashian had long been rumored to fill the position. Her friendship with new X Factor judge Demi Lovato helped seal her deal, a source said.

Kardashian and Lopez screen-tested separately. It's unclear whether they've been on camera together yet.

Lopez is no stranger to hosting gigs, as he anchors the entertainment news show "Extra" as well as MTV's "America's Best Dance Crew." Kardashian, on the other hand, is known in the reality TV world with her family's hit series "Keeping Up With the Kardashians," but has limited on-camera hosting experience. Kardashian has hosted two radio programs in the past, one in Miami and one in Dallas, but according to Simon Cowell, her lack of experience is what he likes most about her.

K&M are expected to debut on the show in November.

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