His older brothers Jens Nicolai and Hans Peter ran the family company Jenssen & Co; Jens Nicolai later founding a rivalling company Jenssen & Sønner in 1837.
Lauritz Dorenfeldt Jenssen enrolled as a student in 1821, and graduated with the cand.theol.
degree in 1831.
However, he did not become a priest.
In 1836 he bought the farm Ranheim in Strinden for 23,000 Norwegian speciedaler, and ran a "significant" industrial company here.
He also served as mayor of Strinden municipality, from 1844 to 1845 and 1850 to 1853.
In July 1836 Jenssen married Karen Amalie Hagerup (1811–1890), a daughter of Caspar Peter Hagerup and sister of Henrik Steffens Hagerup.
Their son Lauritz established the paper factory Ranheims Papirfabrik, and also served as a politician.
Through his son, Lauritz Dorenfeldt Jenssen was the grandfather of politicians Hans Jørgen and Worm Hirsch Darre-Jenssen.
Through his sister Nicoline, who married his wife's brother Henrik Steffens Hagerup, he was also the uncle of Prime Minister Francis Hagerup.