Jonathan's most notable parts were in The Karate Kid, Part III playing Cobra Kai villain Snake and then in Rocky V as a drug addict. His father, John G. Avildsen directed both films. Avildsen's role as Snake – the cackling sidekick to "Karate's Bad Boy" Mike Barnes – in The Karate Kid, Part III marked the pinnacle of his career.
- The Karate Kid, Part III (1989) as Snake 
- Rocky V (1990) as Druggy
- Gone Fishin' (1997) as Parking Lot Valet
- Inferno as Petey Hogan
- Jane Bond (2001) as Operator
- White Boy (2002) as Cole
- 8 juli 2007. "Snake – LA's Bad Boy". YouTube. Retrieved 2010-03-22.