Born in 1876 in Port Adelaide, Australia, Amy Eleanor Mack was the daughter of the Rev. Hans Hamilton Mack, and his wife Jemima James, both of whom immigrated to Australia from Ireland. Mack was one of seven children, and her sister Louise Mack was also to become a writer. She was educated at the Sydney Girls' High School, and went to work as a journalist after graduation.

Mack was editor of the 'Women's Page' of the Sydney Morning Herald from 1907-14, publishing her first book, a collection of essays entitled A Bush Calendar, in 1909. Her first children's book, Bushland Stories, was published in 1910. She married zoologist Launcelot Harrison in 1908, and the two traveled to England in 1914, where he did his postgraduate work at Cambridge. Mack worked in London as a publicity officer for the ministries of munitions and food during WWI.

In 1919, the couple returned to Australia, where Harrison worked as a professor of zoology at the University of Sydney from 1922. Mack published her book, The Wilderness, that same year, and continued to contribute to the literary page of the Sydney Morning Herald. She was honorary secretary of the National Council of Women of New South Wales from 1920-23, and accompanied her husband on scientific expeditions until his death in 1928. Mack herself died in 1938.