In 1993, aged 19, Rex began his career, responding to a modeling advertisement in a Los Angeles magazine and agreed to be photographed nude for photographer Brad Posey and his Club 1821 studio. The following year, under the alias Sebastian, he appeared in solo masturbation scenes for three Club 1821 pornographic films: "Young, Hard & Solo #2", "Young, Hard & Solo #3", and "Hot Sessions III". Archive footage was used in the 2000 films "Hot Sessions 11" and "Hot Sessions 12". In 1994 Rex went on a modeling tour for Tommy Hilfiger, before going on to appear in mainstream modeling gigs for Calvin Klein, Versace, and Levi’s.