Kukkapuro fell asleep in his home outside Helsinki on Saturday, according to his daughter Isa Kukkapuro-Enbom.
"Almost all Finns have sat on a chair designed by him – at a metro station, in a bank, at school or at a library", writes Studio Kukkapuro in a press release.
"Yrjö Kukkapuro never stopped designing and coming up with new ideas. Right up to the end, he was pondering a concept for his new chair, whose plan was clear in his head."
His chairs are represented in the collections of the Museum of Modern Art in New York and the Victoria and Albert Museum in London.
Yrjö Kukkapuro was 91 years old.
