Although active as an established author for nearly four decades, it was particularly after his Juloratoriet (The Christmas Oratorio) was adapted as a movie in 1996 that he became widely known to the (Swedish) public.

[1] Inspired by the example of Norwegian author Axel Jensen Tunström moved to the Greek island of Hydra, in late 1957 or early 1958 and rented a house.

In 1983, Tunström made his breakthrough with Juloratoriet which depicted the sufferings and tribulations of three generations of the Nordensson family in Sweden in the 20th century.

Tunström is considered a major writer of the Swedish literature of the late 20th century and is recognized for his complex exploration of interpersonal relationships through a style that is reminiscent of Gabriel García Márquez and which is sometimes compared to magical realism.

The cover paintings of his first two books about Sunne (De heliga geograferna and Guddöttrarna) are made by the painter Tage Åsén from the same town.