She excitedly tweeted the news, writing: "The rumours are true... I will be hosting @TheXFactorUSA this season! So excited!"
And, to show there's no hard feelings, sister Kim also took to Twitter to congratulate her sibling, writing: "OMG!! How exciting is this?! Khloe is joining The X Factor this November to co-host with Mario Lopez."
She added: "I'm so happy for Khloe and can't wait to watch her on the show. I can't think of anyone more perfect for the role!!! Xo."
And we can't wait for fashion watch to begin...