When she was 13, Barros and her older sister, Patricia, were vacationing in Rio de Janeiro when they were spotted by a representative from Elite Model Management.[9] Barros was encouraged by the Rio Elite office to participate in the Elite Model Look 1996, which she was runner up to Diana Kovalchuk. Barros subsequently competed for international Elite Model Look and placed second worldwide.[6] Elite sent her portfolio and recent Polaroid shots to GUESS? which led her to do the Millennium GUESS? campaign along with her friend and fellow Brazilian model Alessandra Ambrosio.[10]
She has been on numerous covers of magazines such as Glamour, Vogue, Marie Claire, Allure; Brazilian magazines such as Capricho and Audi magazine, W, Elle to name a few.[11] Barros appeared seven times on Sports Illustrated in the Swimsuit Issue (2002, 2003, 2004, 2005, 2006, 2007, 2008).[9] Barros was named number 96 in FHM magazine's "100 Sexiest Women in the World" supplement in 2006.
Barros was the ambassador for Italian lingerie brand Intimissimi from 2005 to 2008. In August 2014 she was announced once again as the new face for Intimissimi.[16] In March 2014, she appeared in an ad campaign for Azzaro Fragrance with Ian Somerhalder.[17]