Gunilla Hansson was born in Stockholm. She was a child who did not enjoy going to school: strong and independent, she struggled to function and meet academic demands. The only subject in which she consistently excelled was drawing.

After a poor secondary school performance, she attended art school at the age of 15 and felt as if she were floating on clouds. She began her studies in textiles in 1955 but soon switched to advertising and book design, where she received graphic training. From 1961, she worked as a graphic designer at Albert Bonniers Förlag in Stockholm. Since 1965, she has been a freelance artist and illustrator, illustrating books and designing book covers for various Swedish publishers.

She particularly enjoys drawing for young children. It is likely the memories of her wonderful preschool years and the time when her own children were small that are reflected in her images. Gunilla Hansson is married and has two children.