Louis spilled the beans about the hot US stars earlier today (7 October) during an appearance on ITV chat show Loose Women.
Clearly not meaning to let the cat out of the bag, he blurted out: "Pharrell and Taylor Swift will be guests this weekend - that's an exclusive!"
Irish star Louis appeared on Loose Women to talk about this year's X Factor and confirmed that there will be four wildcards added to the mix on the weekend.
The judges will be picking a wildcard for each other and Cheryl Fernandez-Versini has already chosen one for Louis - but he did keep quiet about who it is. Boo!
Meanwhile, it is also thought Louis' new boy band will be officially named during the first live show. Fans have been making suggestions for a moniker and Louis says they have been inundated.
"There is still no name," he said. "But 45,000 people have sent in names, so there will be a name!"
The boy band has a whopping eight members, which is a new challenge for Louis, but he is happy to mentor such a huge group.
He explained: "There are eight members, but in Korea they have all these big bands with 10, 12, even 20 people. It'll be good."
Louis, who has been the show's longest serving judge, then added: "It's the best job in the world.
"It's great that Simon and Cheryl are back and Mel B in great fun too. Give the show a chance this year, the music is going to be really, really good."