He is perhaps best known for the collaborative work with his partner Maj Sjöwall on a series of ten novels about the exploits of Martin Beck, a police detective in Stockholm, published between 1965 and 1975.

In 1971, The Laughing Policeman (a translation of Den skrattande polisen, originally published in 1968) won an Edgar Award from the Mystery Writers of America for Best Novel.

Subsequently, he was involved in the New Left journal Tidsignal (Time Signal) (1965–1970) where he was part of the editorial board, among others including the writer Kurt Salomonson [sv].

[2] A leftist tendency and a dramatically effective narrative distinguished Wahlöö's early novels about power and the right, for example A Necessary Action from 1962, which depicts Franco's Spain, and his Dictatorship series.

Novels written by Per Wahlöö alone (see Martin Beck for joint collaboration with Sjöwall) He has been described as a part of "the couple who invented Nordic noir",[4] and he is credited as one of the main inspirations for the Norwegian writer Jo Nesbø.