He was born in Vardal as the son of Hans Mustad and Marie Heyerdahl. On the maternal side he was a great-grandson of Hieronymus Heyerdahl, and on the paternal side he was a grandson of Ole Hovelsen Mustad, great-grandson of Hans Schikkelstad, nephew of Kristian Mauritz Mustad and cousin of Sigbjørn Mustad.
They settled at Lysaker in Bærum. The company had been passed from his great-grandfather through the generations, and grown significantly since its beginnings in Vardal. In 1875 the company had expanded with a new factory at Lilleaker in Kristiania, followed in 1889 by a foundry at the same place as well as a new margarine factory.
In addition, the company expanded abroad.
The expansion continued after 1918, and the company eventually became the world"s largest producer of fish hooks. Despite the ownership change, the name O. Mustad & Søn was kept.
After his death, O. Mustad & Søn was converted to a limited company (1970) and split into different branches (1977 and 1997).
