| Year | Title | Role | Notes |
| 1967 | NET Playhouse | Boy | Episode: "An Evening Journey to Conway Massachusetts" |
| 1969 | The Good Guys | Mike Butterworth | Episode: "Take a Computer to Lunch" |
| 1970 | The Name of the Game | Watson | Episode: "Man of the People" |
| 1972–79 | M*A*S*H | Cpl. Walter "Radar" O'Reilly | 174 episodes (seasons 1-8) |
| 1973 | Love, American Style | Sydney Melvin Wimple / Wilbur Wright | Episodes: "Love and the Crisis Line", "Love and the Plane Fantasy" |
| 1974–75 | Insight | Milo / Mombo | Episodes: "Five Without Faces", "The Incredible Man" |
| 1974–81 | Match Game | Self | Episodes: 311-315, 331-335, 341-350, 356-365, 371-415, 417-470 (129 episodes, 1974-75). Recurring appearances afterwards from 1975 to 1981 |
| 1976 | Ellery Queen | Gerald Hacker | Episode: "The Adventure of the Disappearing Dagger" |
| 1977 | The Love Boat | Donald M. Flanders | Episode: "The Captain's Captain/Romance Roulette/Hounded (A Dog's Life)" |
| 1978 | America 2-Night | Himself | Episode: "Help Every Little Person" |
| 1978 | Fantasy Island | Richard C. Delaney | Episode: "Superstar/Salem" |
| 1978 | The New Adventures of Wonder Woman | Alan | Episode: "The Man Who Wouldn't Tell" |
| 1979 | $weepstake$ | Roscoe Fuller | Episode: "Roscoe, Elizabeth, and the M.C." |
| 1980 | Fantasy Island | Gordon Hughes | Episode: "The Love Doctor/Pleasure Palace/Possessed" |
| 1981 | The Love Boat | Eddie Martin | Episode: "Maid for Each Other/Lost and Found/Then There Were Two" |
| 1981 | Tales of the Unexpected | Harry Flock | Episode: "The Best Policy" |
| 1984 | AfterMASH | Walter "Radar" O'Reilly | Episodes: "Yours Truly, Max Klinger", "It Had to Be You" |
| 1984 | W*A*L*T*E*R | Unsold pilot |
| 1984 | Carnival of the Animals | himself/host | TV special featuring music of Camille Saint-Saëns |
| 1995 | Burke's Law | Patrick Noyes | Episode: "Who Killed the Hollywood Headshrinker?" |
