Though her parents were wary at first, they eventually supported their daughter’s sudden change in course, which Sims credited as being a key factor to her success. As her career progressed, Sims appeared in many of the top fashion magazines, including Elle, Vogue and Madame Figaro. Magazine covers soon turned into advertisements, as Sims appeared for Nautica, Armani, Chanel and Victoria’s Secret.

But Sims knew that she wouldn’t be a model forever, so she began to segue into acting, first by hosting the long-running MTV fashion series, “House of Style”. Since “House of Style” helped launch the on-air careers of famous supermodels Cindy Crawford and Rebecca Ramijn-Stamos, it was no wonder the still-unknown Sims was nervous about the prospect. A few months after what she thought was an awful screen test, Sims got a callback and eventually the job in 2000. Sims went on to other hosting gigs—mainly TV specials—including “Victoria’s Secret Fashion Show 2001”, “World’s Sexiest Athletes” (2002) and “MTV’s Mardi Gras 2002”. She also appeared in a series of popular commercials for Old Navy, and, as a former competitive swimmer, Sims posed for numerous Sport’s Illustrated swimsuit editions.

Sims’ transition into acting continued in 2002, when she appeared on an episode of the Fox sitcom “Andy Richter Controls the Universe" and in an episode of UPN's short-lived “The Twilight Zone” revival: in a remake of the original series' the “Eye of the Beholder” episode, Sims played a woman who discovers that beauty is, indeed, in the eye of the beholder. Next Sims landed a regular series role in “Las Vegas” (NBC, 2003 - ) playing the sexy, manipulative Delinda Deline, daughter of casino chief Big Ed Deline (James Caan), whose dalliances with her dad's top employee Danny McCoy (Josh Duhamel) strain relationships between the three.