The evening, held at Kensington Palace, showcased some of the costumes from Jolie's new movie Maleficent.
While Pitt, 50, was there to provide red carpet support, the movie is very much a family affair – it is the first time Jolie has worked with her children on screen, and she told reporters it was "great to act" with them. (Their oldest child, Maddox, 12, also attended the event, wearing all-black, like his parents, with a red tie.)
Jolie, 38, dazzled onlookers in a floor-length black beaded backless dress, Louboutin heels and wore her long hair up in a chignon accessorized with diamond earrings.
The actress, filmmaker and UNHCR Special Envoy also used the occasion to raise awareness of the kidnapped Nigerian schoolgirls, saying, "We should attack [the kidnappers] from all sides."
Also at the event was Elle Fanning who said of her Oscar-winning costar, "The first time I met her at the studio, she gave me a great big hug and said, 'We're going to have so much fun doing this.' "
And even though a former PEOPLE Sexiest Man Alive was standing nearby, when asked who her Prince Charming would be, Fanning, 16, told reporters, "I've always had a crush on Ryan Gosling."
Actor Sam Riley was asked what it was like to be Jolie's minion. "There are worse jobs," he said. "It was fun being her lackey."
The World of Maleficent costume exhibit will be on display at Sky Studios in London's O2 arena from May 24 to June 14.