Lewis made her film debut as a teenager in the 1986 Roman Polanski film Pirates. She followed it that same year with the female lead in The Golden Child alongside Eddie Murphy. Later appearances include the film Tripwire (1990) and Storyville (1992, opposite James Spader). She had a co-starring role in Men of War (1995, alongside Dolph Lundgren) and in the 1995 film Decoy. Lewis appeared in the 2003 film Hey DJ.
Lewis also appeared in a cover-featured pictorial in the July 1993 issue of Playboy magazine.
On 14 May 2010, Lewis and her Los Angeles-based attorney Gloria Allred accused Polanski of sexually assaulting the Actress when she was 16 years old, before the two worked together on Pirates. Prosecutors in Los Angeles confirmed that they interviewed Lewis in connection with the allegations. According to Lewis, the alleged incident occurred at Polanski's apartment in Paris. In a 1999 interview, Lewis stated that she had been his girlfriend for six months after the shooting of Pirates.
Lewis attended Bishop Douglass School in Finchley. Her mother is of Irish-English extraction, while her father—a physician whom she never met—is half-Chilean and half-Iraqi.