Born in Ixelles, in the Brussels-Capital Region, he was the son of Gustave Saintenoy and Adele Cluysenaar. He is the grandson of the famous architect Jean-Pierre Cluysenaar. His residence in Brussels was the Hotel Saintenoy, that became a listed monument in 1992.
He married Louise Ponselet, who is the niece of Jan Verhas. The little Louise figured on several paintings of her uncle.
They had two children:
He began studying architecture in Antwerp in 1881 then returned home to complete his training in Brussels. With an interest in archaeology, for a time he served as the general secretary of the "Royal Society of Archaeology" in Brussels. In 1910 he embarked upon a teaching career at the Académie Royale des Beaux-Arts in Brussels.
At the end of World War I, Saintenoy was appointed a member of the "Royal Commission of Monuments and Sites" where he played an important role in the reconstruction of Belgium following the devastation of the war.