Tore Ahlsén grew up in Gröndal, a suburb of Stockholm. Since Ahlsén’s father was a carpenter he and his brother Erik got an insight in the building industry from an early age. In 1926 Tore began studying at Tekniska Skolan (later Konstfack), in Stockholm and after a few years of internships, he went on to study engineering at the KTH, Royal Institute of Technology. After graduating, Tore Ahlsén worked at KFAI (The Swedish Cooperative Union architectural and engineering office) for more than 20 year.
Ahlsén also worked with the architects Erik Lallerstedt and Gunnar Asplund. From 1937 and onwards Tore Ahlsén ran an architectural studio together with his brother Erik. In 1938 they got a commission from the City of Stockholm to create furniture for an exhibition. Their work led up to the foundation of KF´s own furniture department, with the aim of producing simple and functional furniture of good quality and at a low price.
As architects the Ahlsén brothers created Sweden’s first district center, in the suburb of Årsta (1943-63), the residential area Henriksdalsberget in Nacka (1964-69) and the department store Kringlan in Södertälje which opened in 1965. The brother’s style of architecture was a kind of modified functionalism, with a strong sense for material, colour and volumes. For the annex to the department store PUB in Stockholm and the community center in Örebro, the Ahlsén brothers received the Kasper Sahlin architectural award in 1963 and 1965.
In 1942 Tore Ahlsén created the garden chair Pia, with a frame made of galvanized steel tubes and a foldable seat made of oiled teak. He also constructed a lamp with the same name, made of crosswise taut metal wires. Both Pia pieces were originally produced by KF but are since 1960s a part of the collection at the furniture manufacturer Gärsnäs.
Tore Ahlsén was also active as a glassware designer, connected to the glasswork Målerås, and he is represented at the Swedish National Museum of Fine Arts. In 1983 Ahlsén was promoted honorary doctor at KTH The Royal Institute of Technology. Five years later he died at the age of 85.