He was born in Trondhjem as a son of landowner and politician Christian Pierre Mathiesen (1870–1953) and Celina Ihlen (1874–1948).
[2] On the maternal side he was a grandson of Jacob Thurmann Ihlen and Belgian citizen Ambrosine Pauline Rouquet.
[1] After mergers and acquisitions through history, the company is now known as YX Energi.
He was a member of the board or supervisory council of many companies, including Wilh.
Olsen & Co, Forsikringsselskapet Norden, Den norske Creditbank, Arthur Mathiesen & Co, Elkem, Norsk Elektrisk & Brown Boveri, Tønsberg Margarinfabrik and Farmand Fabriker.