Although born in Ohio, he grew up (from the age of 7) in Oklahoma and attended school only until he was 13. Thereafter, he held many odd jobs until, at the age of 20, he set out for California. Boyd began his film career in 1918 with a role in Cecil B. deMille's Old Wives for New, and he appeared throughout the 1920s in films made by deMille. He first played the role of the cowboy hero in 1935 in the film Hopalong Cassidy. With his tall stature and white hair, Boyd was a distinctive figure; wearing a black hat and costume and riding a white horse, he quickly became identified by the public with the screen hero. He played the role in subsequent films until the late 1940s and then reenacted it for a television series, also called Hopalong Cassidy (1952–54).