Ryan was born in Melbourne to surgeon Sir Charles Snodgrass Ryan and Alice Elfrida, née Sumner. He had one sister, Ethel Marian "Maie" Sumner, would later marry Richard Casey. Ryan attended Geelong Church of England Grammar School 1895–98 before travelling to England to complete his education at Harrow School and the Royal Military Academy, Woolwich.

In 1904, Ryan was commissioned in the Royal Artillery. At the outset of the First World War, he was stationed on the Western Front. At the end of the war (1918) he was a lieutenant colonel, and was awarded three foreign honours and the Distinguished Service Order in 1918, having been wounded in 1915 in the Battle of Festubert.

Ryan was the chief of staff to the governor of Cologne in 1919, and was shifted to the Inter-Allied Rhineland High Commission headquarters in 1920. He married Lady Rosemary Constance Hay, the daughter of the high commissioner the Earl of Erroll, at the British consulate on 29 May 1924. They had one child, Patrick Vincent Charles Ryan, and divorced in 1935, whereafter he returned to Victoria to Edrington, the property he had inherited near Berwick. He and his sister built the station into a very successful Romney Marsh stud; he also built a landing strip there in 1939.

Ryan was appointed a Companion of the Order of St Michael and St George in 1928, and acted as high commissioner following Erroll's death until the end of the occupation. At his retirement from the army in 1929, he became an arms salesman with Vickers Ltd, in which capacity he travelled to Moscow and Bangkok. He resigned in 1934. At the outbreak of the Second World War, Ryan joined the Australian Military Forces, holding administrative posts until 1940, when he was elected to the Australian House of Representatives for Flinders as a member of the United Australia Party.

Ryan was not particularly prominent in Parliament, serving on joint committees on social security (1941–46) and foreign affairs (1952), the latter of which he was the chairman. He was described by Enid Lyons as "a doughty champion of women". Ryan remained in Parliament until his sudden death of cardiac failure on 25 August 1952; he was cremated, and survived by his son.

• Langmore, Diane (2002). "Ryan, Rupert Sumner (1884–1952)". Australian Dictionary of Biography. National Centre of Biography, Australian National University. ISSN 1833-7538. Retrieved 16 March 2008.