Sven Kai-Larsen studied at what today is Konstfack University of Arts, Crafts and Design in Stockholm from 1940-42. After graduation Kai-Larsen worked for a couple of years at the architectural office of KF (Coop) under Olof Tunström and later at the office of Ancker-Gate-Lindgren.
In 1953 Kai-Larsen founded his own interior architect studio in Stockholm, which also have offices in Gothenburg, Malmö, Linköping and Örebro, making it the largest in Sweden with over 70 employees. Kai-Larsen made interiors for several major projects during the 1950’s and 60’s, such as the Sheraton Hotel and the offices of the Swedish newspapers Dagens Nyheter and Expressen in Stockholm. He also designed the interior for hospitals in Stockholm, Gothenburg and Linköping and schools in Umeå and Karlskoga.
As a furniture designer Kai-Larsen worked mainly with interiors for offices and public space, for producers such as NK Verkstäder. In 1964 Kai-Larsen was the exhibition designer for Form Fantasi at Liljevalchs. For the exhibition he designed a connectable stool made of laminated birch or jacaranda which is one of his best known pieces.
Kai-Larsen worked with cabinetmakers Rälta Snickeri for whom he designed a modernistic chair in oak with a seat and back in leather, which is a part of the collection at the Museum of Furniture Studies. In the 1970’s Kai-Larsen’s studio was closed. Sven Kai-Larsen passed away at the age of 70 in 1990.