The actor - best know for his character disappearing and nearly missing his wedding after a particularly raucous bachelor party in the film series - tied the knot with Pilates instructor Lia Smith in Hawaii yesterday (04.01.14).
The couple were wed just before sunset on the island of Oahu at a historic fishing pond with an altar made of sticks. A reception was then held at the nearby Kualoa Ranch venue.
Among guests were Jesse Eisenberg, Reese Witherspoon and her husband, Jim Toth, who is Justin's agent, and 'The Hangover' co-star Ken Jeong.
A source told UsMagazine.com: "Lia wore a white dress with thin spaghetti straps and jeweled sandals. Justin wore a dark colored suit and burgundy socks. They were sweet together and looked very in love. He was holding her bouquet for her and walked with his arm around her after the vows.
"She had a big smile on her face and nuzzled her face up to his neck. Their family and friends seemed so happy for them and had an incredible time hanging out in Hawaii leading up to the wedding. It was a destination wedding for all."
Justin, 35, and Lia - who hails from Hawaii - were first linked in January last year when they celebrated the start of 2013 together on a Maui beach.
The actor then proposed in May when they made a romantic trip to Big Sur, California.
An insider said at the time: "The trip to Big Sur, the engagement, the ring, everything. So cute."