He was born in Ranheim in Strinden Municipality as a son of estate owner and politician Lauritz Jenssen (1837–1899) and Jørgine Wilhelmine Darre (1842–1910).

[2] In July 1895 in Lillehammer he married Sigrid Støren (1871–1935), a daughter of a lieutenant colonel.

He then stayed a few years abroad, returning to Norway to build railway lines.

[1] Darre-Jenssen had entered politics in 1904, when he was elected to the executive committee of Kristiania city council.

He left in 1919 after a conflict with Knudsen's Second Cabinet, to become CEO of the tramway company Akersbanerne from 1919 to 1935.