The entertainment news Web site described it as an intimate ceremony that came the day after a pre-wedding party.
E! News said several dozen guests had spent the night camping out in air-conditioned tents.
There also was a large white tent set up and a truck delivered orchids, E! News said.
McConaughey, 42, whose movie credits include 2009's "Ghosts of Girlfriends Past" and 2008's "Tropic Thunder," and Alves, a 30-year-old former model from Brazil who is now a handbag designer and TV host, met in 2007. They have two children together, Levi, nearly 4, and Vida, 2.