[1] His parents were Jeanne Marie Adélaïde Liégeard, and Louis Eugène Jules Doynel Count de Saint-Quentin (14 October 1850 - 18 April 1928).
De Saint-Quentin graduated from École libre des sciences politiques, and joined the Foreign Ministry in 1907.
[2] During World War I, he was drafted and wounded twice, he receiving several decorations; he was French military attaché in the British army in Egypt.
He was stationed at the General Secretariat of the Berlin Peace Conference, and to the Protectorate of Morocco, he became in 1926 deputy director of African-Levant.
De Saint-Quentin served as the ambassador to the United States from March 1938 to September 1940.