Zimmermann was discovered by a scouting agency in Porto Alegre, Brazil at the age of 14 and made her way to Japan and onto Paris. Shortly thereafter, Steven Meisel booked her for the cover of Italian Vogue, September 2000, and her modelling career began in earnest.

Zimmermann's friends at school conviced her to pursue modelling as a career. She is known for being very professional and polite to everyone. As for a plan after modelling, she says she would like to work with something creative.

Zimmermann has campaigned for such brands as: Balenciaga, Bloomingdales, Cavalli jeans, Cerruti, Chanel eyewear, Chloé, Christian Dior, CK by Calvin Klein, Clairol, Dolce & Gabbana, Dsquared, Emanuel Ungaro, Escada, Fendi, GAP, Gucci, Giorgio Armani, H&M, Hermes, Hugo Boss, Louis Vuitton, Lanvin, MAC Cosmetics, Max Mara, Neiman Marcus, Prada, Roberto Cavalli Valentino, Versace, and appears regularly in American Vogue, French Vogue, Italian Vogue, W, Harper's Bazaar, Visiona