[citation needed] Tryon began his acting career appearing on stage in Wish You Were Here (1952), Cyrano de Bergerac (1953), and Richard III (1953).

He also guest-starred in 1955 as Antoine De Mores in the two-part episode "King of the Dakotas" of NBC's western anthology series Frontier.

His film debut was in The Scarlet Hour (1956) at Paramount, directed by Michael Curtiz, a crime drama about a man whose married lover persuades him to commit a robbery; Tryon received second billing.

He was top billed in a low budget war film at Allied Artists, Screaming Eagles (1956), then supported Charlton Heston and Anne Baxter in Three Violent People (1956) at Paramount.

Tryon appeared in the lead in "The Mark Hanford Story" (February 26, 1958) on NBC's Wagon Train with Onslow Stevens and Kathleen Crowley.

In 1962, Tryon was cast to play the role of Stephen Burkett ("Adam") in the unfinished Marilyn Monroe-Dean Martin comedy film, Something's Got to Give, directed by George Cukor, but lost that role after Monroe was fired from the movie; the picture was remade with Doris Day and James Garner as Move Over, Darling (1963) with Chuck Connors playing Tryon's part.

The film was a box office hit and Tryon received a nomination for a Golden Globe Award for Best Actor – Motion Picture Drama.

"[7] Tryon later guest-starred on Kraft Suspense Theatre and then was reunited with Preminger in In Harm's Way (1965) starring John Wayne and Kirk Douglas.

He also co-wrote a song, "I Wish I Was", which appeared on an obscure record by Dick Kallman, star of the short-lived 1965 television sitcom Hank.

Other television roles include episodes of The Big Valley, Bob Hope Presents the Chrysler Theatre, and the 1967 TV movie remake Winchester '73 in which Tryon played James Stewart's original role with a supporting cast featuring Dan Duryea, John Drew Barrymore, Joan Blondell, John Dehner and Paul Fix.

His best-known work is The Other (1971), about a boy whose evil twin brother may or may not be responsible for a series of deaths in a small rural community in the 1930s.

[9] Other novellas in the collection were based on the murder of former silent screen star Ramón Novarro and on the complicated relationship between actor Clifton Webb and his mother.

His novel The Night of the Moonbow (1989) tells the story of a boy driven to violent means by the constant harassment he receives at summer camp.

[13] During the 1970s, he was in a romantic relationship with Clive Clerk, one of the original cast members of A Chorus Line and an interior designer who decorated Tryon's apartment on Central Park West in New York City, which was featured in Architectural Digest.