Kai Krstiansen trained as a cabinet maker, finishing his apprenticeship in 1948. In 1950 he was accepted into the Academy of Fine Arts where he studied furniture design under Kaare Klint. In the mid fifties he opened his own design office where he collaborated with manufacturers such as Schou Andersen Mobelfabrik, Fritz Hansen, Magnus Olesen, Feldballes, Axel Kjaersgaard and Heltborg.
Over his career he designed many items representing the Danish Modern style - everything from writing desks, tables, sideboards, chairs, bar cabinets and TV-stands. His #42 chair designed for Schou Andersen is now an iconic piece of Danish modern furniture and still one of his most popular designs, sought after not only for it's striking and well-crafted frame but also for it's comfort and functionality.