Steinfeld made his film debut in the 1979 film Americathon. He had the lead role of the killer in the early slasher film Home Sweet Home (1981). Other film roles include Cheech and Chong's Next Movie (1980), Into the Night (1985), The Money Pit (1986), and Coming to America (1988). He supplied the voice of Git, a lab rat in the Disney animated feature Ratatouille and as the Fish Teller in the 2011 English version of From Up On Poppy Hill.
Steinfeld founded Major League Lacrosse (MLL), the first professional outdoor lacrosse league, in 2001. MLL has nine franchises in North America; the championship trophy, is named the Steinfeld Cup.
