Gemma’s big break came when she was sent to casting director, Russell Marsh, who booked her exclusively for Prada’s Spring 2002 runway show in Milan. She went on to shoot two ad campaigns,Versus with “star-making” photographer Steven Meisel, and Jill Stuart with Mario Sorrenti. Since then, Gemma has appeared in campaigns for Prada, Dior, Valentino, Hermes, Karl Lagerfeld, Jil Sander, Y-3, Yves Saint Laurent, Calvin Klein, Balenciaga, Burberry, Louis Vuitton, Jean Paul Gaultier, Dolce & Gabbana, and Swarovski as well as being the face of Calvin Klein’s fragrance, Obsession Night, and Kose Cosmetics. In various other capacities, she has worked with Glosser, Tommy Hilfiger, JAG, Hardy
Brothers Jewellery, Zara and Zimmerman. She has appeared on the covers and pages of Vogue (Italian, American, British, French, Australian, Chinese, Japanese, Indian), W, Time, i-D, Numero, Harper’s Bazaar,V, and PoP. Gemma is the youngest model in history to appear on the cover of American Vogue, where she was featured in the special “Return of the Supermodel” issue. Gemma also starred on the cover of the premier issue of both Vogue China and Vogue India, and is the first model to ever appear on the cover of Teen Vogue. In addition to modeling, Gemma also enjoys acting. She made her feature film debut starring opposite Liv Tyler and Scott Speedman in the suspense thriller "The Strangers." She also starred in “Black Balloon,” a heart-warming drama, which co-stars actress Toni Collette. Gemma was nominated for an Inside Film Award, a prestigious Australian honor, for her role in “Black Balloon”. She appeared in the third installment of the Pirates of the Caribbean franchise, “Pirates of the Caribbean: On Stranger Tides,” alongside Johnny Depp as well as the film adaption of the classic novel “The Great Gatsby,” directed by Baz Luhrmann and co-starring Leonardo DiCaprio.