The couple, dubbed Brangelina, previously said they would not tie the knot until all couples were able to marry.
Speaking to Esquire magazine in October 2006, Pitt said: "Angie and I will consider tying the knot when everyone else in the country who wants to be married is legally able."
Jolie, the daughter of actor Jon Voight, was previously married to Trainspotting star Jonny Lee Miller and US actor Billy Bob Thornton.
Pitt was engaged to Gwyneth Paltrow before meeting Jennifer Aniston, whom he divorced in 2005 after five years of marriage.
Following the divorce, T-shirts bearing the slogans Team Aniston and Team Jolie became fashion must-haves in the US.
Pitt and Jolie announced their engagement in 2012, with Pitt's manager describing it as "a promise for the future" at the time.
Cynthia Pett-Dante, Pitt's manager, added: "Their kids are very happy."
Jeweller Robert Procop worked with Pitt for a year to design Jolie's diamond engagement ring.
The jeweller went on to design numerous pieces with Jolie, including a ring for the actress to wear during premiers of her film Maleficent this year.
However all proceeds from the ring will go to charity, a statement on Procop's website states.