He was elected to the Norwegian Parliament from Vest-Agder in 1945, and was re-elected on six occasions. He was President of the Lagting for three terms. During his seventh term, in December 1972, Røiseland joined the Liberal People's Party which split from the Liberal Party over disagreements of Norway's proposed entry to the European Economic Community.
On the local level, Røiseland was a member of Holummunicipal council between 1931 and 1940.