Stig Lönngren studied cabinet making in Västervik before moving to Stockholm and what today is Konstfack University of Art, Craft and Design from where he graduated in 1951. During the 1950’s Lönngren worked as interior architect for Carl-Axel Acking and Sven Hesselgren as well as for Arne Rudberger and Gösta Åbergh.
From 1961 Lönngren worked in the architectural office of KF and four years later he joined the office of Peter Celsing where he stayed until 1968. Lönngren worked for architect Kempe & Ljunglöf until 1974 when he founded his own studio.
Stig Lönngren was the initiator of the HI-group that was founded in 1959, consisting of cabinetmakers (sv. Hantverkare) and interior architects (sv. Inredningsarkitekter) working closely together to re-new the Swedish furniture industry form mass-production to craftmanship. The aim was to show that Swedish design could measure up to the Danish, which was the most successful both national and international. While in the group, Lönngren designed a.o. the children's high chair HI 56 that was made in orange painted birch plywood by carpenter Lars Larsson and was shown at the HI-Group’s exhibition in 1963. The HI 65 was acquired by the Swedish National Museum of Fine Arts in 2020.
As a furniture designer Lönngren is also known for the chair Pampas that he designed together with Jerry Zetterman for Bröderna Zetterman AB in 1975 and that is a part of the collections at both the Swedish National Museum of Fine Arts and the Museum of Furniture Studies in Stockholm.
