He made his stage debut in an Off-Broadway production of Little Mary Sunshine and received a nomination for the Tony Award for Best Featured Actor in a Play for The National Health.

Other stage credits included revivals of The Time of Your Life (1969), Beggar on Horseback (1970), Twelfth Night (1972) and The Man Who Came to Dinner (1980).

Frey was nominated for the Academy Award for Best Supporting Actor for his performance as Motel the tailor in Norman Jewison's 1971 film Fiddler on the Roof (he had appeared in the original Broadway musical production as Mendel, the rabbi's son).

Other film credits included roles in The Magic Christian (1969), Tell Me That You Love Me, Junie Moon (1970), Where the Buffalo Roam (1980),[3] Up the Academy (1980),[3] and Tattoo (1981).

[3] Frey's television credits included appearances on Hallmark Hall of Fame; Medical Center; Mission Impossible; Eight Is Enough; Quincy, M.E.