Knight was born Tadeusz Wladyslaw Konopka in the Terryville section of Plymouth in Litchfield County, Connecticut, to Polish-American parents, Sophia (Kavaleski) and Charles Walter Konopka, a bartender. Knight dropped out of high school to enlist in the United States Army in World War II. He was a member of A Company, 296th Combat Engineer Battalion, earning five battle stars while serving in the European Theatre.
During the postwar years, Knight studied acting in Hartford, Connecticut. He became proficient with puppets and ventriloquism, which led to steady work as a television kiddie-show host at WJAR-TV in Providence, Rhode Island, from 1950 to 1955. In 1955, he left Providence for Albany, New York, where he landed a job at station WROW-TV (now WTEN), hosting The Early Show, featuring MGM movies; and a kids’ variety show, playing a "Gabby Hayes" type character named "Windy Knight". He was also a radio announcer for sister station WROW radio. He left the station in 1957 after receiving advice from station manager (and future Capital Cities Chairman) Thomas Murphy that he should take his talents to Hollywood.
Knight spent most of the 1950s and 1960s doing commercial voice-overs and playing minor television and movie roles. He had a small part playing a police officer seen guarding the room where Norman Bates, now in custody, sat wrapped in a blanket at the end of Alfred Hitchcock's Psycho (1960). He also guest starred on the syndicated television series Sea Hunt with Lloyd Bridges, during the 1961 season in the episode titled "The Defector". In the 1962-1963 season, he appeared as "Haskell" in the short-lived drama and situation comedy The New Loretta Young Show on CBS. He played Phil Sterling on the ABC soap opera The Young Marrieds in the early 1960s. He appeared frequently in television shows such as The Invaders, Highway Patrol, How to Marry a Millionaire, Peter Gunn, Bourbon Street Beat, The Donna Reed Show (in the episode "April Fool" on April 1, 1959), Pete and Gladys, The Eleventh Hour, Bonanza, The Man and the Challenge, Combat!, McHale's Navy (including one episode as boy Admiral "Go Go" Granger), Get Smart, The Lieutenant, The Twilight Zone, Gunsmoke (as Mr. Rabb, esq.) and The Wild Wild West. His final movie role was in the golf comedy Caddyshack, where he played Judge Elihu Smails, who is fed up with the shenanigans of Al Czervik, a guest at his golf club (played by Rodney Dangerfield).
Knight's distinctive speaking voice brought him work as an announcer, notably as narrator of most of Filmation studio's superhero cartoons as well as voice of incidental characters. He was narrator of the first season of the Super Friends, while other animated television series featuring his work included the voices of the opening narrator and team leader Commander Jonathan Kidd in Fantastic Voyage.
His role as the vain and untalented WJM newscaster Ted Baxter on The Mary Tyler Moore Show brought Knight widespread recognition and his greatest success. He received six Emmy Award nominations for the role, winning the Emmy for "Outstanding Performance by an Actor in a Supporting Role in Comedy" in 1973 and 1976.
In 1975, Knight recorded an album of mostly novelty songs, "Hi Guys", on the Ranwood label (which was co-founded by Lawrence Welk and re-released many of his earlier albums). The title track, in which Knight tries to get out of various embarrassing situations by using his signature "Hi, Guy!" line, received some play on the Dr. Demento show.
Knight used some of this character's style for regional commercials. In the Cleveland area during the early to late 1970s, a newsman simply known as "Ted" would provide news of the events at a local shopping center known as Southgate USA, often finishing the 60-second spot with a comedic flair, including wearing a jacket that resembled his blue "WJM" blazer. The spots were produced by UAB Productions for Southgate USA. UAB Productions was the local production arm of United Artists Broadcasting, which owned WUAB-TV in the Cleveland area at that time. Knight also returned to Albany to do some hilarious promo spots for his former employer, WTEN's local news show.
After The Mary Tyler Moore Show's run, Knight guest-starred in "Mr. Dennis Steps Out," the October 26, 1977, episode of the situation comedy Busting Loose, as Roger Dennis, the owner of an escort service in New York City. This episode was spun off into its own show, The Ted Knight Show, giving Knight his first starring role. The Ted Knight Show was a disappointment, lasting for only six episodes in the spring of 1978.
Knight appeared in a few episodes of The Love Boat, including one episode as a rival cruise captain, Captain Gunner Nordquist, versus Mary Tyler Moore Show co-star Gavin MacLeod's Captain Merrill Stubing. This was broadcast in March 1982 as Season 5, Episodes 24 and 25, of The Love Boat, whose segments were titled "Pride of the Pacific," "The Viking's Son," "Separate Vacations," "The Experiment," and "Getting to Know You."
Knight landed the lead role as the kind, curmudgeonly cartoonist Henry Rush in the series Too Close for Comfort in 1980. During scenes in which Henry draws in his bedroom, Knight used his earlier acquired ventriloquism talents for comical conversations with a hand-puppet version of his comic book's main character "Cosmic Cow." Throughout the run of the series, Knight would wear sweatshirts from various colleges and universities, which were often sent to him by students who were fans of the show. The show was cancelled by ABC after three seasons, but was revived in first-run syndication in 1984 and proved to still be popular. In 1986, the show became The Ted Knight Show and saw Henry Rush retire from cartooning and become part owner of a weekly newspaper. The new format allowed the show to remain a hit, and a second season had been planned until his health had become a factor.
In 1948, he married Dorothy Smith, and the couple had three children: Ted, Jr., Elyse, and Eric.
In January 1985, Knight was awarded a star on the Hollywood Walk of Fame for his contributions to the television industry. It is located at 6673 Hollywood Boulevard.
A few months after the end of the Mary Tyler Moore Show in 1977, Knight was diagnosed with cancer for which he received various forms of treatment over several years. In 1985, the cancer returned as colon cancer which, despite rigorous treatment, eventually began to spread to his bladder and throughout his lower gastrointestinal tract.
Knight continued to work, even after having surgery to remove a tumor from his urinary tract. However, he experienced complications from the surgery and was advised not to resume work on Too Close For Comfort until he recovered. Knight's condition continued to worsen and he died on August 26, 1986, at the age of 62.
Knight was interred in the Forest Lawn Memorial Park in Glendale, California. His grave marker bears the name Theodore C. Konopka (and, at the bottom, the words "Bye Guy", a reference to his Ted Baxter catchphrase "Hi, guy!")
His hometown of Terryville, Connecticut, dedicated the bridge on Canal Street over the Pequabuck River in his memory. There is a bronze plaque bearing his likeness on the bridge.Man on a String (1960) - Prof. Vasheen (uncredited)
13 Fighting Men (1960) - Samuel
Twelve Hours to Kill (1960) - Police Sgt. Denton
Psycho (1960) - Policeman in Hallway Opening Door (uncredited)
Cage of Evil (1960) - Lt. Dan Ivers (uncredited)
Key Witness (1960) - Cowboy's Lawyer (uncredited)
Swingin' Along (1961) - Priest
Cry for Happy (1961) - Lt. Glick
The Great Impostor (1961) - Reporter (uncredited)
13 West Street (1962) - Baldwin
Hitler (1962) - Maj. Buch
The Pigeon That Took Rome (1962) - Steve (uncredited)
The Interns (1962) - Photographer's Assistant at Fashion Shoot (uncredited)
The Candidate (1964) - Frank Carlton
Young Dillinger (1965) - Johnsyn
Blindfold (1965) - Dr. Bob Berford (uncredited)
Countdown (1967) - Walter Larson
MASH (1970) - Offstage Dialog (voice, uncredited)
Cold Turkey (1971) - Mr. Slick (uncredited)
Emilio and His Magical Bull (1975)
Caddyshack (1980) - Judge Elihu Smails