Helge Rognlien received his law degree in 1945. He was chairman of Unge Venstre, the youth organisation of the Liberal Party in 1946-1948. From 1952 until 1960 he was a teacher and in 1960, he became chief welfare officer in Bærum, a local community just outside Oslo. He held that position until 1967, when he became chairman of Trygderetten, the National Health Insurance Court. From 1972 he worked as a judge until his retirement.
Rognlien was engaged in local politics as a representative of the Liberal Party in 1956-1960 and in 1976-1979, and he was a member of the non-socialist coalition government in 1970-1971. He was a member of the Norwegian Nobel Committee from 1966. He resigned from the committee in 1973 after having opposed the award to Henry Kissinger and Le Duc Tho.