Dudley McCarthy graduated from the University of Sydney and worked in the bush during the depression years of the 1930s and as a patrol officer in New Guinea. In 1940 he enlisted in the Second A.I.F. as an infantry private; he fought in North Africa and was a Rat of Tobruk. He also fought in New Guinea, finishing the war as a major.
After World War II McCarthy worked in the then Australian Civil Service. In 1963 he was appointed the Australian Minister at the United Nations in New York, USA, and later as the first Australian Ambassador to Mexico and as the Ambassador to Spain.
He retired to Canberra, Australian Capital Territory, and was Chairman of the Film Board of Review. He wrote radio plays, television documentaries and South-West Pacific Area - First Year : Kokoda to Wau (1959), part of a series published by the Australian War Memorial. He also wrote Gallipoli to the Somme : the story of C.E.W. Bean (1983), and the children's information book, World War 1 Years (1986), part of the Hodder Australia Everyday Life in Australia series.