Jens Mogens Boyesen (9 October 1920 – 20 November 1996) was a Norwegian diplomat and politician for the Labour Party.
He was born in Kristiania as a son of deputy under-secretary of state Einar Theiste Boyesen (1888–1972) and Borghild Koppang (1888–1978). He had a younger brother Einar who was killed during the Second World War. Fleeing occupied Norway after his involvement in Milorg was discovered, Einar Boyesen enrolled in the Norwegian Independent Company 1 and was killed during a mission in Norway in March–April 1945.
From 1944 to 1947 Jens Boyesen was married to Alix Dorry Sophie Theslöf. She later married Erling Steen. In 1955 he married journalist Erle Sigrun Bryn, a daughter of Norwegian Maritime Director Erling Bryn.
At the time Norway was invaded by Germany in 1940, Boyesen was a law student and member of the Labour Party. He had also a member of the socialist organization Mot Dag. The Labour cabinet Nygaardsvold fled to London in order to avoid an early capitulation. Germany occupied Norway for five years, whereas Boyesen became a part of the resistance movement. He was a messenger for both the Norwegian government-in-exile and the , communicating on behalf of the so-called Kretsen, an inner circle of the resistance movement for which he was the secretary. Within Kretsen, he cooperated especially close with former Supreme Court Justice Ferdinand Schjelderup. Approaching the winter of 1944, Boyesen was no longer safe in Norway, and fled to Sweden. He worked as a secretary for the Norwegian legation in Stockholm until the liberation of Norway in 1945.
After the war Boyesen finished his law studies, graduating as cand.jur. in 1947. He worked as a deputy judge from 1948, and then as an advisor in the Ministry of Foreign Affairs from 1949. He then spent many years as a State Secretary in Torp's Cabinet, first in the Ministry of Foreign Affairs from 1951 to 1954 and in the Ministry of Defence from 1954 to 1955. He later returned as State Secretary in the Ministry of Foreign Affairs from 1963 to 1965, during Gerhardsen's Fourth Cabinet.