In 2000, Roberts portrayed real-life environmental activist Erin Brockovich in her fight against the Pacific Gas and Electric Company (PG&E) of California in the film Erin Brockovich, for which she became the first actress to be paid $20 million for a film; Rolling Stone magazine's Peter Travers wrote, "Roberts shows the emotional toll on Erin as she tries to stay responsible to her children and to a job that has provided her with a first taste of self-esteem", while Entertainment Weekly critic Owen Gleiberman felt that it was a "delight to watch Roberts, with her flirtatious sparkle and undertow of melancholy". Erin Brockovich made $256.3 million worldwide, and Roberts won the Academy Award for Best Actress for her role. In December 2000, Roberts, who had been the highest-paid actress through the 1990s, became the first actress to make The Hollywood Reporter's list of the 50 most influential women in show business since the list had begun in 1992. In the same year, her Shoelace Productions company received a deal with Joe Roth.
Roberts and her husband, cameraman Daniel Moder, met on the set of her film The Mexican in 2000 while she was still dating Bratt. At the time, Moder was married to Vera Steimberg. He filed for divorce a little over a year later, and after it was finalized, he and Roberts wed on July 4, 2002, at her ranch in Taos, New Mexico. Together, they have three children: twins, a daughter and a son, born in November 2004, and another son born in June 2007.
In 2000, Roberts narrated Silent Angels, a documentary about Rett syndrome, a neurodevelopmental disorder. The documentary was designed to help raise public awareness about the disease. In July 2006, Roberts became a spokeswoman for Earth Biofuels, as well as chair of the company's newly formed Advisory Board promoting the use of renewable fuels. She supported Gucci's "Chime For Change" campaign that aims to spread female empowerment.