Prince William and Taylor Swift joined Jon Bon Jovi to sing his '80s mega-hit 'Livin' on a Prayer.'
All three took the stage at the Centrepoint Winter White Gala at Kensington Palace in London Wednesday.
Centrepoint is a charity that helps the homeless.
Taylor Swift sang her hits 'Trouble', 'Love Story' and '15', but her impromptu performance with the Duke of Cambridge and Bon Jovi was the grand finale.
Swift said performing at the palace was, "Just amazing."