Born in London, Ponsonby attended Harrow and Trinity College, Cambridge then went onto a career in law in 1903. On June 25, 1925, he married Roberte de Neuflize, the only daughter of Baron Jean de Neuflize of Paris. They had four children.
Lord Bessborough held public office prior to becoming Governor General. He held a seat in the London County Council from 1907 to 1910 and was elected to the British House of Commons as Member of Parliament for Cheltenham from January 1910 to December 1910, and for Dover from 1913 to 1920.
Upon the death of his father, he succeeded to the Earldom in the Irish peerage as 9th Earl of Bessborough and entered the House of Lords.
After World War I, he pursued a successful business career, holding directorships in several large commercial firms including deputy chairman of De Beers Consolidated Mines.
During the Second World War, he helped establish a department in the Foreign Office that looked after the welfare of French refugees in Britain. He made one last visit to Canada in 1956 and died in Stansted in 1957.