Her Cuban-American father Emilio Diaz worked as a foreman for an oil company, and her mother Billie Early (whose ancestry includes English, German, and Native American) worked as an exporting agent.

Cameron attended Long Beach Polytechnic High School. At age 16, she landed a modeling contract with the prestigious Elite Model Management. After graduating high school, she went to work in Japan and met video director Carlo de la Torre. On her return to America, she moved in with him. For the next few years, her modeling took her around the world, working for contracts with major companies.

At the age of 21, Diaz auditioned for Jim Carrey's The Mask. To her own surprise, and with no previous acting experience, she was cast as the female lead. Immediately after getting the part, she signed up for acting lessons.

Over the next three years, she won roles in low-budget, independent films, such as The Last Supper, Feeling Minnesota, and She's The One.

She then regained mainstream success with My Best Friend's Wedding and There's Something About Mary, and won critical acclaim for Being John Malkovich, which earned her Best Supporting Actress nominations at the Golden Globes, the BAFTA Awards and the SAG Awards.

Diaz has also starred in the hit adaptation of Charlie's Angels and its sequel, and she voiced a lead character in Shrek and its sequel, for which she earned $10 million. In 2001, she won nominations for Best Supporting Actress at the Golden Globes, the SAG Awards and the AFI Awards for Vanilla Sky. For Charlie's Angels: Full Throttle, she became the second actress (after Julia Roberts) to earn $20 million for a role; the film underperformed at the box office.