And our own One Direction singer Niall Horan was at the centre of the fun.
He joined winner Tate Stevens and his mentor LA Reid, who was also marking his last night on Simon Cowell's show.
Country singer Tate went for a relaxed look, with a brown leather jacket, cowboy hat and jeans.
He posed for snaps on the red carpet with Cowell who went for the old reliable: black suit and crisp white shirt.
Despite his girlband, Fifth Harmony, losing out to Tate in the final, music mogul Cowell was all smiles.
Adding more glamour was American superstar and X Factor judge Britney Spears.
Britney went all-out with a floor-length, cleavage-enhancing black gown, with her blonde locks pinned back.
Fellow judge Demi Lovato opted for the gladiator look with a metallic gold mini-dress.
She themed the strappy number with large gold hoop earrings and wore her hair in long loose curls.
Show presenter Kourtney Kardashian showed off her tanned legs in a short glitzy number.
Fresh from performing at the X Factor finale night was heartthrob boy band One Direction.
The five lads look relaxed as they went for cool and casual in black and navy outfits.
Singer Liam Payne (19) led the way with a long white shirt under a black waistcoat, while Louis (20) and Harry (18) looked dapper in shiny black suit jackets.
The most casual of the group were Zayn Malik (19) who plumped for a leather jacket and Niall, all smiles in a T-shirt.
Mullingar native Niall was clearly enjoying the female attention after recent remarks about his happily single status.
The boyband performed their new single Kiss You for the first time on US television, taken from the album Take Me Home.