After his debut role in the horror film "Clownhouse" in 1989, which he filmed while living in San Francisco, he moved to New York and trained at the William Esper Studios with teacher William Esper. His career slowly gained momentum in the early 1990s, when he alternated between small-screen guest spots in TV series like "The Equalizer", "NYPD Blue" and "Law & Order" and small roles in films such as "Last Exit to Brooklyn" and "Teenage Mutant Ninja Turtles". He also appeared as the title character in "The Search for One-eye Jimmy" (1994). During this time, Rockwell worked in restaurants as a busboy and delivered burritos by bicycle. At one point, Rockwell even worked as a private detective's assistant. "I tailed a chick who was having an affair and took pictures of her at this motel", he told "Rolling Stone" in 2002. "It was pretty sleazy." A well-paying Miller commercial in 1994 finally allowed him to pursue acting full-time.