Diaz, 42, and Madden, 35, had been dating since May and got engaged shortly before Christmas, People reported.
“We couldn’t be happier to begin our new journey together surrounded by our closest family and friends,” the couple told the magazine.
Diaz, a Golden Globe-nominated actress, most recently starred in the film “Annie,” a reworking of the Tony-winning 1977 Broadway musical of the same name.
Madden is best known for performing in the rock bands Good Charlotte and The Madden Brothers with his twin brother Joel Madden.
A representative for the couple told People that the two were married at “an intimate ceremony at their home in Los Angeles.”
Representatives for Diaz and Madden could not immediately be reached for comment.