It's official … Khloe Kardashian and Mario Lopez will be the new co-hosts of “X Factor'.

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

The duo's salaries will add millions to the budget — on top of an already enormous talent budget … with Britney Spears in the lead at $15 mil.

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