Roberson was born near Shannon, Texas, the son of farmer Ollie W. Roberson and Jannie Hamm Roberson. Raised on cattle ranches in Shannon, Texas, and Roswell, New Mexico, he left school at 13 to become a cowhand and oilfield roughneck. He married and took his wife and daughter to California, where he joined the Culver City Police Department and guarded the gate at MGM studios. Following army Service in World War II, he returned to the police force. During duty at Warner Bros. studios during a labor strike, he met stuntman Fred Kennedy, who alerted him to a stunt job at Republic Pictures. Roberson got the job, due both to his expert horsemanship and his resemblance to John Carroll, whom Roberson doubled in his first picture, Wyoming (1947). His close physical resemblance to John Wayne led to nearly 30 years as Wayne's stunt double. He often played small roles and stunted in other roles in the same film, which frequently resulted in his "shooting" himself once the picture was cut together. He graduated to larger supporting roles in westerns for Wayne and John Ford, and to a parallel career as a second-unit Director.

Bob Dylan drew him as Long Tom in his Beaten Path series, the drawing is entitled "Untitled 1" and is based on a frame from the film Winchester '73 (1950).

In 1979 he published an autobiography entitled “The Fall Guy: 30 Years as the Duke's Double” (ISBN 088839036X). Roberson died of cancer in Bakersfield, California and is buried next to his brother, actor Lou Roberson in Los Angeles.

His television appearances include The Lone Ranger, The Adventures of Kit Carson, Lawman, Death Valley Days, Have Gun – Will Travel, Laramie, Gunsmoke, The Virginian, Laredo, Bonanza, Daniel Boone, and The Big Valley. Roberson also appeared in Disney's television Westerns The Swamp Fox and Texas John Slaughter. They were part of The Wonderful World of Color. Prior to that, he portrayed a Confederate Prison Captain in The Great Locomotive Chase.