Halvorsen was born at
Ålesund in
Møre og Romsdal, Norway. He was a merchant by profession. He started his business career as a sales representative in
Vanylven Municipality in
Sunnmøre. In 1874 he became a director at Selje forbruksforening in
Nordfjord. He later worked as a representative for several factories and businesses in
Bergen. In 1881, he established himself as a merchant in
Trondheim with a fish wholesaler. Halvorsen was a member of the city council of Trondheim 1895-1904 and again from 1910. He represented the city in the
Norwegian Parliament 1898-1900 and 1903–12. He was
Minister of Finance from 1907 to 1908 in cabinet of Prime Minister
Jørgen Løvland. ==References==