Magnus Stephensen graduated from the Kunstakademiets Arkitektskole (Royal Danish Academy of Fine Arts, School of Architecture) in 1931 and set up his own design studio. In his early career he designed apartment buildings, schools and waterworks. Later he designed smaller objects to be used in the home. He designed silver serving pieces for the Kay Bojesen Silversmithy (1932 - 52), Ceramic pots and dishes for Royal Copenhagen (1950s) and silver ("Fregat/Argo" pattern) and stainless flatware ("Tuja" pattern) and hollowware pieces for Georg Jensen (1950 on). (Kay Bojesen was one of Georg Jensen's first apprentice's and became an important Danish silversmith and designer who believed in functionalist design. Stephensen's work reflected Bojesen's influence.)

Stephensen's hollowware designs for Jensen are characterised by subtle lines and unornamental forms. Many of the pieces draw on traditional Japanese design. In fact, Stephensen wrote a book called "Brugsting Fra Japan" ("Useful Things from Japan").

Stephensen work was included in many important exhibitions around the world and he received many prizes. He was awarded the Eckersberg medal (1948) and several medals at the Milan Triennale.