Maria Lang was born in Västerås. Daughter of a newspaper editor, she passed the upper secondary school leaving examination in 1933, studied at Stockholm University, and completed a PhD in literary history in 1946. From 1948 to 1974, she was director of studies and lecturer at the primary and lower secondary school for girls Nya Elementarskolan för Flickor in Stockholm. She never married.
A crime writer of English-style whodunnits, she made her debut in 1949 with Mördaren ljuger inte ensam, which caused a stir with its frank depiction of a secret lesbian relationship as the key to the murder mystery. Between 1950 and 1990, she brought out a new detective novel each year, in which the characters are largely driven by sexual motives and urges, such as in Kung Liljekonvalje av dungen, 1957, and Dubbelsäng i Danmark, 1975. Each time, the pipe-smoking detective Christer Wijk solves the crimes with his logical reasoning and cool intellect.
In ...att vara kvinna, published in 1961, there are references to the debate on women's rights at that time. Maria Lang also wrote detective novels for teenagers. Most of her forty or more detective novels have been republished and translated into various languages.