At age 16, she began her career as a fashion model. Diaz contracted with modeling agency Elite Model Management. For the next few years she worked around the world for contracts with major companies. She modeled for designers such as Calvin Klein and Levi's. When she was seventeen years old she was featured on the front cover of the July 1990 issue of the magazine Seventeen.
She returned to mainstream films with the major movie successes My Best Friend's Wedding (1997) and There's Something About Mary (1998), for which she was nominated for a Golden Globe Award for the category of Best Actress — Musical or Comedy. She received critical acclaim for her performance in Being John Malkovich (1999), which earned her Best Supporting Actress nominations at the Golden Globe Award, the British Academy of Film and Television Arts Awards, and the Screen Actors Guild Awards (SAG Awards). During 1990–2000, Diaz featured in many movies, such as Things You Can Tell Just by Looking at Her, Very Bad Things, Any Given Sunday, and the successful adaptation of Charlie's Angels. During 2001, she won nominations for Best Supporting Actress for the Golden Globe Awards, the SAG Awards, the Critics' Choice Awards, and the American Film Institute Awards for Vanilla Sky, and also voiced Princess Fiona in the movie Shrek, for which she earned $10 million.
During 2003, Diaz received another Golden Globe nomination for Martin Scorsese's epic Gangs of New York, and became the third actress (after Wedding costar Julia Roberts) to earn $20 million for a role, receiving the sum for Charlie's Angels: Full Throttle. Her next movies were In Her Shoes (2005), and The Holiday (2006). She was preparing to work again with The Mask co-star Jim Carrey for the film Fun with Dick and Jane, but resigned to feature in In Her Shoes. Diaz reportedly earned $50 million during the period of a year ending June 2008, for her roles in What Happens in Vegas opposite Ashton Kutcher, and the Shrek sequels. In 2009, she starred in My Sister's Keeper and The Box.