Harrison worked as a portrait photographer and a builder of house trailers when he had his first story published in 1936. His first novel Boothill Trail was published in 1940. During his career, he wrote up to 1200 novels, non-fiction books and pulp and magazine stories.

Harrison's Collier's Weekly two part magazine story 'Petticoat Brigade' was adapted into the 1957 film The Guns of Fort Petticoat. Under the name Will Hickok he wrote three western novels: Web of Gunsmoke (1955), as well as two tie-ins to the television show, The Restless Gun (1959, 1960).

His non-fiction works include Conservation, the Challenge of Reclaiming our Plundered Land, Find a Career in Auto Mechanics, Here Is Your Career: The Building Trades and Here is Your Career, Auto Mechanic.