In 1999, at the age of 16, Isabeli fontana appeared in the Victoria's catalogue. The shoot caused controversy, as Victoria's Secret stated that they would not use girls younger than 18.Soon after the Victoria's shoot, she was signed by Versace, Ralph Lauren and Valentino.
Since 1999 she has modeled for Sports Illustrated Swimsuit Issue, Marie Claire, ELLE, Vogue, Harper's Bazaar, Numéro, i-D, Arena and many others.
Fontana has been the face of a variety of advertising campaigns including Armani Jeans, Dolce and Gabbana, Philips, Ralph Lauren, Revlon, Tommy Hilfiger, Versace and others.