He was born in Kristiania as a son of genealogist Stian Herlofsen Finne-Grønn (1869–1953) and Margrethe Borchgrevink (1873–1963).
He started working in the Norwegian Ministry of Foreign Affairs in the same year, and he was stationed as a secretary at the consulate in Marseille from 1933 to 1934, the legation in Ankara from 1934 to 1936, in Norway from 1936 to 1937, in New York City in 1937, the legation in London from 1941 to 1946, and in Brussels from 1946.
He was the Norwegian ambassador to Czechoslovakia and Hungary from 1952 to 1958, to Chile, Peru and Bolivia from 1960 to 1966, and Portugal from 1966[1] to 1975.
Czechoslovak citizen Vladimír Veselý was convicted for spying for Norway, and sentenced to 25 years of prison.
Veselý had allegedly had contact with Norwegian intelligence officer Einar Nord Stenersen,[4] who had indeed been dispatched to the Norwegian embassy, officially to locate surveillance bugs (which he did), but Finne-Grønn was aware of the clandestine nature of Stenersen's work.