After her father's death at the age of 26 from tuberculosis in 1940, when Hanrahan was just a year old,[1]  she lived with her mother (a commercial artist), her grandmother, and her great aunt (who had Down syndrome).

[4] She began writing her first book, The Scent of Eucalyptus (1973), a semi-autobiographical consideration of her childhood in the 1940s and 1950s in Thebarton, shortly after the death of her grandmother in 1968.

[8] Hanrahan's work is personal and private yet its themes are universal, portraying relationships between girlfriends, women and men, and the struggle against societal structures.

These themes are constantly repeated throughout her oeuvre in prints, such as in Wedding night (1977)[8] and Dear Miss Ethel Barringer (1975).

By the 1960s many women were not virgins at the time of marriage, and Hanrahan's Wedding Night depicts the outdated assumption that for consummation to happen the woman must be pure.

[2] Hanrahan’s work is described as exploring the “themes of society and its norms, its expectations and its conventions and how the individual fares therein - buffeted and withstanding, weak and strong.

The subjects are clearly chosen, gleaned from a lifetime of careful looking, listening, reading, digesting and remembering.”[1] Critic and art historian Alison Carroll draws parallels between the simplicity of Hanrahan's scenes and David Hockney's pop art; “Hanrahan uses Hockney, but, in her best work of the periods, she moves on considerably from him; she achieves a high emotional pitch, working with uncomfortable themes of love, family and relationships and using awkward childlike form.

The process goes far beyond the easy, self-controlled world of Pop art.”[2] Carroll implies that the simplicity in both Hanrahan and Hockney's drawings are similar.

Hanrahan exhibited her artwork internationally, including in London, Italy, Japan, New Zealand, Sweden, Scotland, the United States and Canada.

Her work Generations (1991) was used as the cover art for Mixed matches : interracial marriage in Australia, by June Duncan Owen.

“Confusion between reality and the imagination was key to barbara writing, lending it a particular and distinctive atmosphere.”[1] Hanrahan's book, Sea Green features a narrator, Virginia and her move from Adelaide, South Australia to London.

[19] Hanrahan concludes: “What we want now in Adelaide are writers and artists who work from the heart of those commonplace suburban streets, who recognise the weirdness of the ordinary, who record it before the version of it we have now is swept away.

We want passion and intensity, an art that comes from places like Port Adelaide and Thebarton and Holden Hill; that stays unofficially weird.“[19][20] The column was republished in the 1989 anthology Eight Voices of the Eighties : Stories, Journalism and Criticism by Australian Women, edited by Gillian Whitlock.