Addie Walker was born in Charters Towers, Queensland, the daughter of James Walker and Emily Jane Meredith. Her father, a master builder in civil life, was a Boer War veteran and also served as lieutenant-colonel with 25 Battalion during World War I. Addie completed her secondary education at Kambala Church of England Girls' School, Rose Bay, and matriculated from there in 1920. She entered the faculty of medicine, Sydney University, in 1921 and, in 1926, graduated with second-class honours and the Dagmar Berne Prize for proficiency amongst women students. She subsequently held resident appointments at Royal Prince Alfred Hospital, the Royal Hospital for Women, Paddington, and the Children's Hospital, Camperdown. Postgraduate study in England followed.

In 1932, Addie was appointed honorary physician to Rachel Forster Hospital and, in that same year, established a general practice at 1 Waratah Street, Rushcutters Bay in an area which, however respectable in itself, lies adjacent to Kings Cross where, at that time, internecine strife between the notorious Razor Gang and other criminal groups produced frequent casualties. Addie could describe, with considerable humour, several extraordinary situations in which she had become involved when called to aid such casualties, all of which undoubtedly gave a unique spice to her practice but contributed nothing to the alleviation of her quite serious hypertension, of which she had first become aware in student days.

Her large practice, her duties as senior honorary physician at Rachel Forster and her work in the outpatients' departments at Crown Street Women's and Royal Prince Alfred Hospitals demanded much of her, while, on a personal level, she accepted responsibility for her ailing parents and her deceased brother's family, all of whom shared her home and, to some extent, her bounty.

An excellent physician, elegant, witty, widely read, a polished raconteuse, of a rare sincerity and, perhaps because of that, sometimes disturbingly forthright, Addie Walker ultimately succumbed, in 1954, to the severe and progressive hypertension which supra- and sub-diaphragmatic splanchnicectomy and sympathectomy in 1944-45 had failed to control.