He was born in Stord, and was the older brother of politician and educationalist Johan David Haslund Gjøstein.
[2] An instrument maker by profession,[3] Gjøsteen became involved in the growing worker's movement in Norway.
[1] Although not a member of Parliament, he marked himself as a proponent of universal suffrage and dissolution of the personal union between Sweden and Norway.
[1] General suffrage would be introduced in 1898 for men, and 1913 for women, whereas the union was dissolved in 1905.
In the field of education, Gjøsteen served as a member of the school board in Kristiania from 1896 to 1923, chairing it from 1914 to 1919.