He won two Emmy Awards for Outstanding Supporting Actor in a Drama Series for Hill Street Blues in 1981 and 1982.

In 1972, Conrad played Michael Stivic's conventional Polish-American Uncle Casimir on two episodes of All in the Family.

[2] The same year, he appeared, together with Richard Crenna and Alain Delon, in the French-language film Un flic, directed by Jean-Pierre Melville.

He also had a memorable role in the 1974 film The Longest Yard, playing Nate Scarboro, a retired NFL tight end (New York Giants) who was also the head coach for "the Mean Machine", the team of prisoners put together by Burt Reynolds's character Paul Crewe to play the team of guards.

Philip Freemason Esterhaus on the 1981–1987 police drama Hill Street Blues, a role he played for 71 episodes until his death.