Roles in films like Safe Passage with Susan Sarandon and the Tim Blake Nelson directed Eye of God followed, but it was his role in the teen horror Disturbing Behavior that got him noticed by the public. Unfortunately, the film flopped, but Nick did an excellent job playing his character, going from outcast Gavin to Blue Ribbon Gavin.

Nick continued working with roles in Terrence Malick's The Thin Red Line and Sunset Strip alongside Jared Leto, in which he played a wannabe rock star. In 2001, Nick appeared in a supporting role in the Academy Award nominated drama In The Bedroom. He gained more notice and critical acclaim, and went on to appear in small projects like Bully with Brad Renfro. Bully is based on a true story in which he played Bobby Kent, who was murdered by his "friends" after tormenting them for years.

In 2003, Nick surprised a lot of people by starring in the blockbuster Terminator 3: Rise of the Machines, taking over the John Connor role from Edward Furlong. After that, he went on to star in the critically acclaimed HBO series Carnivàle for two seasons.

Most recently, Nick appeared as the Yellow Bastard in Frank Miller's Sin City. He can next be seen in A Cool Breeze on the Underground based on the mystery novel by Don Winslow. Nick plays Neal Carey, a 23-year-old graduate student whose college education is paid for by the Bank, an exclusive New England institution that keeps its wealthy clients happy and out of trouble. The Bank also teaches him how to be a private investigator.