 In 1947, O'Boyle was hired as head football coach and athletic director at Southwest Missouri State College.He led the Southwest Missouri State Bears football team for two seasons, compiling a record of 16–4–1 and winning the Missouri Intercollegiate Athletic Association title in 1948.O'Boyle worked as an assistant football coach at Kansas State University from 1949 to 1950, at Duke University from 1951 to 1958, and at the University of Miami from 1959 to 1960, before returning once more to his alma mater, in 1961.