Gun Jacobson was born in Sundsvall. She was a social realist teenage fiction writer, who was a teacher and youth worker, directed a children's theatre group, and was active in the temperance movement. She was married and had children.
She made her debut with Fel spor, 1966, and is best known for her novel Peters baby, 1971, which became a type of manifesto for emancipated young men. She also wrote the fantasy-like Salamander, 1978, which is a pastiche of E. T. A. Hoffmann's The Golden Pot of 1814 – an attempt at renewal, which, however, was obstructed by uncomprehending critics.