Christensen rose to prominence in the 1990s, becoming one of the most popular models of her time. In 1990, she starred in the music video for Chris Isaak's song "Wicked Game". The video was later featured on MTV's "Sexiest Video of All-Time", voted #4 on VH1's "50 Sexiest Video Moments", and voted #13 on VH1's "100 Greatest Videos". She became a spokesmodel for Revlon cosmetics in 1992. She appeared on magazine covers including Vogue, Elle, Harper’s Bazaar, and W, and in fashion campaigns including Revlon, Chanel, Versace, Lanvin, Prada, Sonia Rykiel, Hermès, Valentino and Karl Lagerfeld. One noted campaign featured her in a billboard in Times Square, naked, "except for a strategically placed banana leaf." She was in the Victoria's Secret catalog and in their television commercials as one of the original "Angels", along with Tyra Banks, Karen Mulder, Daniela Peštová, and Stephanie Seymour.
