halvorsen was born in kristiania (now oslo) and he debuted in kristiania in 1908. he was a violinist with the national theater orchestra from 1904 to 1906, with the bergen philharmonic orchestra from 1906 to 1907, and in berlin and paris from 1908 to 1914. halvorsen was the concert master for the national theater orchestra from 1915 to 1917, and the conductor at oslo's opera comique from 1918 to 1921, where he conducted a number of opera performances. he was a music critic for the newspaper "tidens tegn" from 1917 to 1918. for a number of years he was the leader of the norwegian string quartet.