"Yes, it's confirmed," Pitt's manager Cynthia Pett-Dante tells PEOPLE. "It is a promise for the future and their kids are very happy. There’s no date set at this time."
Jeweler Robert Procop designed Jolie's engagement ring in collaboration with Pitt.
Jolie, 36, and Pitt, 48, have been together since 2005, and rumors that they planned to marry have circulated for years.
The chatter intensified earlier this year when Pitt told CBS News that they were "getting a lot of pressure from the kids."
The couple have six children together: Maddox, 10, Pax, 8, Zahara, 7, Shiloh, 5, and twins Knox and Viv, 3.
The Los Angeles County Museum of Art / PRNewsFoto