Jonsson, in Lom, Oppland, grew up in a poor family in a small rural community in eastern Norway, and was very attached to his mother. After his mother's death, in June 1950, he moved to Oslo, where he committed suicide on New Year's Day, six months later.

His poems reveal a split presonality. The poet admits that he is a man no one knows, because there is another living inside him, a man who never owned his proper words.

Jonsson had at last one close friend, the poet Jan-Magnus Bruheim. They planned to build a cabin together in the mountains, a cabib Bruheim had to build alone. He called it Torbu ("Tor's cottage") after his friend. Brunheim's poem Venetape (Friend's Loss) is a love poem written after the death of Tor Jonsson.