He was a United Australia Party Member of the House of Representatives (1931–40). He was Australia’s first Minister to the USA (1940–42), joined the British war cabinet (1942–43), and was governor of Bengal (1944–46). On returning to the House of Representatives (1949–60), representing the Liberal Party, Casey held various portfolios including that of External Affairs (1951–60). He was governor-general of the Commonwealth of Australia (1965–69).