Born Warren Higgins in Dallas, Texas, Buetel moved to Los Angeles, California in the late 1930s with the intention of establishing a film career. Unable to find film work, he was employed as an insurance clerk when he was noticed by an agent who was impressed by his looks.

Introduced to Howard Hughes, who was about to begin filming The Outlaw, Buetel was signed to play the lead role as Billy the Kid, with the previously signed David Bacon being fired as a result. Hughes also signed another newcomer, Jane Russell, for the female lead, and realizing the inexperience of his two stars, also signed veteran actors Thomas Mitchell and Walter Huston. Buetel was signed to a standard seven year contract at $150 per week and was assured by Hughes that he would become a major star. Filmed in late 1940 and early 1941, The Outlaw officially premiered in 1943 but did was not widely seen until 1946. It was notable as one of the first major films to suggest the act of sexual intercourse, and was also controversial for allowing characters to commit sins on film, without a suitable punishment also being represented. Much of the publicity surrounding the release of the film focussed on Jane Russell, and she established a solid film career, despite critics giving her performance in The Outlaw poor reviews.

Buetel's performance was also highly criticised, and he languished with Hughes refusing to allow him to work. The director Howard Hawks tried to secure his services for the film Red River (1948), but after Hughes refused to allow Buetel to take part, Montgomery Clift was chosen and his career flourished. In 1951 Buetel appeared in Best of the Badmen, his first film appearance in eleven years. Over the next few years he appeared in five more films, and made infrequent appearances on television. His last acting role was in an episode of Wagon Train in 1961. He also appeared as himself in the 1982 Night of 100 Stars television special.

He died in Portland, Oregon and was buried at Portland Memorial Park.