In television, Nicholas had recurring roles on Fox shows as Todd Marsh on Party of Five (2000) and Nick Hutchison on Red Band Society (2014–2015).

[3][4] Nicholas's early roles included appearances in the TV shows Who's the Boss?, Married... with Children and Dr. Quinn, Medicine Woman.

He became known for his roles in the films Rookie of the Year (1993), A Kid in King Arthur's Court (1995) and American Pie (1999).

He also played Nick Hutchison in Steven Spielberg's TV drama series Red Band Society (2014–2015), and had roles in Bilal: A New Breed of Hero (2015), and Sheep and Wolves (2016).

Nicholas is the lead actor in the Lionsgate film Adverse, opposite Mickey Rourke, Sean Astin, Lou Diamond Phillips and Penelope Ann Miller.

[citation needed] In March 2015, Nicholas appeared on Blues Traveler's album Blow Up the Moon, co-writing the song "All the Way.