Making his feature film debut in William Wyler's 1956 film Friendly Persuasion, Richman was, by that time, a regularly employed television actor, as well as a member of New York's Actors Studio, a resource of which he would avail himself frequently until moving to Los Angeles in 1961.

[citation needed] His television credits include Hawaii Five-O, Justice, The Fall Guy, The DuPont Show with June Allyson, Stoney Burke, Breaking Point, The Fugitive, The Outer Limits, Blue Light, The Invaders, Alfred Hitchcock Presents, The Man from U.N.C.L.E., The Wild Wild West, Bonanza, Daniel Boone, The Silent Force, Get Christie Love!, The Bionic Woman, Knight Rider, The Incredible Hulk, Mission: Impossible, Combat!

He appeared as Ralph Offenhouse in Star Trek: The Next Generation's first season episode "The Neutral Zone".

Richman starred in the penultimate filmed episode of The Twilight Zone, titled "The Fear".

Capwell (1984), Longstreet as Duke Paige, on the soap opera Dynasty as Andrew Laird (1981–1984), and a recurring role on Three's Company (1978–1979) as Chrissy's father, Rev.