He pursued his university studies at the Sorbonne, in Paris, where he graduated as Licentiate in Law.
Bossy started his career as diplomat in 1918, after the end of World War I, being private secretary of the Minister of Foreign Affairs.
In 1923 he was recalled and worked as political advisor at the Prime Minister's Office under Ion I.C.
During the minority of King Michael of Romania (1927–30) he was appointed secretary general of the Regency, returning to his diplomatic career as counsellor of Romanian legation in Vienna (1931–34).
In 1934 he was promoted minister plenipotentiary, being assigned to head the legations in Helsinki (1934–36), Budapest (1936–39), Rome (1939–40), Bern (1940–41) and Berlin (1941–43).