The couple were married just before sunset Saturday afternoon on Oahu, PEOPLE confirms.
Reese Witherspoon and her husband, agent Jim Toth, Jesse Eisenberg and Hangover costar Ken Jeong were among the guests who enjoyed a reception at Kualoa Ranch following the ceremony.
The actor, 35, and Smith, a fitness trainer, announced their engagement in May 2013.
They were first seen together in January 2013 when they celebrated New Year's Eve together, basking in the sun on a Maui beach as they kissed and cuddled on the sand.
Bartha, a Florida native who was raised in Michigan, had previously dated Ashley Olsen for two years before splitting in 2011. He has also been linked to Scarlett Johansson.
Pacific Coast News
Reporting by JENNIFER GARCIA