He was born in Trondhjem as a son of Albert Peter Severin Collett (1842–1896) and Nanna Høegh (1854–1921).
His second wife was director's daughter Kathleen Ragnhild Falsen, after dissolving this marriage as well he married Rosa Louise Martens in 1943.
The company was run under the name Firma Albert Collett, from 1909 with Johan's brothers Oscar and Axel as co-owners.
[1] He was a board member of Norsk Træmassekompani,[4] the Paper and Fibre Research Institute and the cartel Mechanical Pulp Suppliers.
He was a supervisory council member of Christiania Theater, Foreningen Norden[5] and Forsikringsselskapet Viking.