Bjorvatn was elected to the Norwegian Parliament from Aust-Agder in 1965, and was re-elected on one occasion.
During his second term, in December 1972, Bjorvatn joined the Liberal People's Party which split from the Liberal Party over disagreements of Norway's proposed entry to the European Economic Community.
Bjorvatn was a member of Tvedestrand municipality council during the terms 1963–1967 and 1967–1971.
He wrote numerous books on local historical topics.
He died at the age of 83 on 9 February 2015[1] and will be buried at Holt Church in Tvedestrand.