The couple married at their home in Austin, Texas on Saturday (09.06.12) and the singer-songwriter performed a song for the pair based on a bible verse.
A witness said: ''He made it into a melody.''
The couple - who have son Levi, three, and two-year-old daughter Vida together - were joined by a number of stars including Woody Harrelson, Reese Witherspoon, Jim Toth and Meg Ryan as they tied the knot.
A wedding guest told Us magazine: ''You could definitely tell [Matthew] was in love. It was a great night for everyone.''
The reception took place in a big party tent where the couple and their guests ate rotisserie-style Brazilian meats and danced to a live band playing American pop and Brazilian rock songs, but the pair skipped the traditional wedding cake and first dance.
Matthew and Camila also whispered their wedding vows to one another, opting to keep their sentiments private, but the 42-year-old actor's words reduced the Brazilian beauty to tears.
The couple set up a high-end campground at their home for their guests to stay in luxury tents for the weekend, and they enjoyed a low-key celebration that included playing lawn games such as beanbag and ring toss.