From 1949 to 1954, Lynch starred in The Plainclothesman on the DuMont Television Network. He appeared in numerous television series. He made three guest appearances on Perry Mason, including the role of Wallace Lang in "The Case of the Stuttering Bishop" in 1959, and Robert Hayden in "The Case of the Irate Inventor" in 1960. Some of the other series in which Lynch appeared are Peter Gunn, Zorro, Have Gun - Will Travel ("Love of a bad woman"), Checkmate ("Cyanide Touch"), The Asphalt Jungle, The Honeymooners, The Fugitive, The Andy Griffith Show, The Dick Van Dyke Show, Blue Light, Adam-12, Star Trek ("The Devil in the Dark"), Maverick, All In The Family, The Twilight Zone ("Mr. Denton on Doomsday"), The Rifleman, and The Wild Wild West. Between 1972 and 1977, he made 16 guest appearances on McCloud, performing as a police sergeant and later a detective named Grover on the series. He previously appeared in 12 episodes of Gunsmoke, 10 episodes of The F.B.I., nine episodes of Bonanza, and six episodes in both The Virginian and Gomer Pyle, USMC. Among the feature films in which he appeared are I Married a Monster from Outer Space, North By North West, The Lawbreakers, Pork Chop Hill, Anatomy of a Murder and Tora! Tora! Tora!. Lynch's last credited performance was in the role of Rear Admiral Talbot Gray in the 1983 seven-part miniseries The Winds of War.