Mendes at the 66th Venice International Film Festival in 2009
She attended California State University, Northridge to study marketing, but dropped out after wanting to begin an acting career. She studied acting under Ivana Chubbuck
She began acting in the late 1990s, and after a series of roles in B movies such as Children of the Corn V: Fields of Terror (1998) and Urban Legends: Final Cut (2000), she broke into the Hollywood mainstream with an appearance in Training Day (2001). She has since starred in many films including All About The Benjamins (2002); 2 Fast 2 Furious, Once Upon a Time in Mexico and Stuck on You (2003); Hitch (2005); Ghost Rider and We Own the Night (both 2007); The Spirit (2008); Bad Lieutenant: Port of Call New Orleans (2009); The Other Guys and Last Night (both 2010).
Mendes has worked as a spokesmodel for Cocio chocolate milk, Magnum ice cream, Revlon make-up, Calvin Klein underwear and perfume, Cartier jewelery, Thierry Mugler perfume, Reebok trainers, Campari apéritif, Pantene shampoo, Morgan clothes and Peek & Cloppenburg clothes. Mendes is the creator of a home decor line, Vida, sold exclusively at Macy's. She launched a bedding collection in 2008 and a dinnerware collection in 2010. Mendes is a singer: she has recorded a version of The Windmills of Your Mind and has collaborated with Cee Lo Green on a song entitled Pimps Don't Cry. She is dating Ryan Gosling and lives in the Los Feliz neighborhood of Los Angeles.
In 2011, Mendes visited Sierra Leone to speak with rape victims and raise awareness of the problems in the area.