He was the son of parish priest (sogneprest) Simen Christoffersen Jønsberg and Karen Dorthea Thesen Arneberg.
He started his career as a chaplain at the church in Drøbak in Frogn Municipality in Akershus county.
[2][3] He was an elected to the Norwegian Parliament in 1842, representing the constituency of Finmarkens Amt,[4] which at that time consisted of both Finnmark and Troms.
Later he was parish priest in Skjerstad Municipality in Nordland county (1843-1855), where he also was elected the mayor of (1844-1848) and (1852-1856).
[5] His grandson Nils Erik Flakstad served as a member of Parliament representing the market towns of Hedmark and Oppland counties.