After leaving office, Denney served as acting secretary of state for Delaware in 1931, commissioner of the State Motor Vehicle Commission in 1940, and was the state librarian from 1941 to 1948. He was also a member of the Republican State Committee from 1920 to 1953, and served as chair from 1926 to 1928. He was chair of the 1922 and 1928 Republican State Conventions, and served as a delegate to the 1908, 1924, and 1928 Republican National Conventions.