[1] Andræ was born at Vena parish in Hultsfred Municipality in Kalmar County, Sweden.

As a historian of religion, his particular interest lay in the early history of Islam, particularly its Jewish and Christian origins, and in the psychology of religion, but he also combined these interests in the study of early Islamic mysticism.

Andræ was a student of Nathan Söderblom, whom he succeeded as member of the Swedish Academy in 1932.

[3] In 1985, Annemarie Schimmel remarked that until then only one study had "tried specifically to depict Muhammad's role in Islamic piety.

Even today Tor Andrae's Die person Muhammeds in lehre und glaube seiner Gemeinde (1918) remains the standard work in this area, unsuperseded by any other major study, though complemented by random remarks in numerous modern work on Sufism.