She and her husband the Duke of Cambridge, aka Prince William, followed the black tie dress code, he in a tuxedo and she in a black lace dress.
The maxi by Alexander McQueen featured a nude lining with intricate lace overlay, was was cinched in at the waist, with a scooped back and sweetheart neckline, a bold sartorial move for Catherine.
She accessorised with some statement earrings, which she has worn in the past, by British brand Erdem, also a favourite’s of Meghan Markle.
The detailed hoops featured some drop pearls, as well as black and grey crystals and burnt orange stones in the middle.
Kate previously wore them to attend an event at the V&A earlier this year, and we all know she’s a big fan of recycling her outfits.
She accessorised with a black clutch bag and her signature pumps, all in all serving up an elegant and timeless party season look.