The couple said, “I do” in the backyard of Diaz’s L.A. home, reports Us Weekly.
Benji’s nephew Sparrow – the son of Joel Madden and Nicole Richie – served as ring bearer.
Bridesmaids included friends Nicole, Drew Barrymore and Jesse Lutz and sister Chimene.
Meanwhile, Reese Witherspoon, Gwyneth Paltrow, Samantha Ronson and Robin Antin were among the celebrity guests who attended. Wedding planners Yifat Oren and Stefanie Cove orchestrated the event, and flowers were provided by The Velvet Garden.
A source told UsWeekly.com after news of their engagement, "Everyone thinks it's wild, but are so happy for them. Benji tends to fall in love easily, but this time it's for real and he landed a great girl. They obviously both make each other incredibly happy, and there's nothing better than that."
Diaz, 42, and Madden, 35, reportedly began dating last May after being introduced by Madden’s sister-in-law, Nicole Richie.