When she was 14, Barros and her older sister, Patricia, were vacationing in Rio de Janeiro when they were spotted by a representative from Elite Model Management. Barros was encouraged by the Rio Elite office to participate in the Elite Model Look 1996, which she won. Barros subsequently competed for international Elite Model Look and placed second worldwide.2 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.

In addition to Guess?, Barros has done advertisements for Christian Dior, Armani Jeans, Oakley, L'Oréal, Naf Naf, Diesel, Ermanno Scervino, Victoria's Secret, Chanel cosmetics, and Jennifer Lopez's JLO fashion line, among others. In 2004 Jennifer Lopez selected Barros to be the face of her new lingerie line, JLO Lingerie. Lopez said, "I wanted someone young, sexy and urban, with a universal appeal". Barros has been in shows for the likes of Valentino, Missoni, Gucci, Christian Dior, Versace, Emporio Armani, BCBG, DKNY, Jean-Paul Gaultier, Dolce & Gabbana, Michael Kors ((Red Oak)), Elie Saab and many more prestigious fashion houses. She walked in the Victoria's Secret Fashion Show in 2002, 2003, 2005, 2006 and 2008.

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. Barros appeared seven times on Sports Illustrated in the Swimsuit Issue (2002, 2003, 2004, 2005, 2006, 2007, 2008). Barros was named #96 in FHM magazine's "100 Sexiest Women in the World" supplement in 2006.

• The Victoria's Secret Fashion Show (2006) (TV) .... Herself/Model
• The Victoria's Secret Fashion Show (2005) (TV) .... Herself (Model)
• Sports Illustrated 40th Anniversary Swimsuit Special: American Beauty (2004) (V) .... Model
• The Victoria's Secret Fashion Show (2003) (TV) .... Herself (Model)
• The Victoria's Secret Fashion Show (2002) (TV) .... Herself (Model)
• MTV Fashionably Loud: Sports Illustrated Edition (2002) (TV) .... Herself (Model)
• MTV Fashionably Loud: Spring Break, Cancun 2000 (2000) (TV) .... Herself (Model)