Johnson was born in Columbus, Georgia. He began his career as a journalist, writing for the Columbus Enquirer Sun, the Savannah Press, the Brooklyn Daily Eagle, and the New York Herald Tribune. He also wrote short stories and a collection of these, There Ought To Be a Law, was published in 1930.
Johnson's first connection with film work was the sale of screen rights to one of his stories in 1927. Johnson asked his editor if he could write film criticism articles in 1932. When this request was denied, he decided to relocate to Hollywood and work directly in the film industry.
Quickly finding work as a scriptwriter, Johnson was hired fulltime as a writer by 20th Century-Fox in 1935. He soon began producing films as well and co-founded International Pictures in 1943 with William Goetz. Johnson also directed several films in the 1950s, including two starring Gregory Peck.
Johnson was nominated for the Academy Award for Best Screenplay in 1940 for The Grapes of Wrath and the Directors Guild of America Best Directors Award in 1956 for The Man in the Gray Flannel Suit.
Johnson died of pneumonia in Hollywood in 1977 and was interred in the Westwood Village Memorial Park Cemetery in Los Angeles.