Mary Jean Cameron was born on 16 August 1865 at Cotta Walla near Goulburn, New South Wales. When Mary was one year old her parents, Donald and Mary Ann, decided to move to Wagga Wagga to join her maternal grandparents, the Beatties, who had moved there from Penrith, New South Wales in 1866.
Gilmore's father obtained a job as a station manager at a property, Cowabbie some 100 km north of Wagga. A year later, he left that job to become a carpenter, building homesteads on properties in Wagga Wagga, Coolamon, Junee, Temora and West Wyalong for the next 10 years. This itinerant existence allowed Mary only a spasmodic formal education; however she did receive some on their frequent returns to Wagga Wagga, either staying with the Beatties or in rented houses.
Eventually, Gilmore's father purchased land and built his own house at Brucedale on the Junee Road, where they had a permanent home. She was then to attend, albeit briefly, Colin Pentland's private Academy at North Wagga and, when the school closed, transferred to Wagga Wagga Public School for two and a half years. At 14, in preparation to become a teacher, Gilmore worked as an assistant at her Uncle's school at Yerong Creek.
After completing her teaching exams in 1882, Gilmore accepted a position as a teacher at Wagga Wagga Public School where she worked until December 1885. After a short teaching spell at Illabo she took up a teaching position at Silverton near the mining town of Broken Hill. There Gilmore developed her socialist views and began writing poetry.
By 1931 Gilmore's views had become too radical for the AWU, but she soon found other outlets for her writing. She later wrote a regular column for the Communist Party's newspaper Tribune, although she was never a party member herself. In spite of her somewhat controversial politics, Gilmore accepted appointment as a Dame of the Order of the British Empire in 1937, becoming Dame Mary Gilmore DBE. During World War II she wrote stirring patriotic verse such as No Foe Shall Gather Our Harvest.
In her later years, Gilmore, separated from her husband, moved to Sydney, and enjoyed her growing status as a national literary icon. Before 1940 she published six volumes of verse and three editions of prose. After the war Gilmore published volumes of memoirs and reminiscences of colonial Australia and the literary giants of 1890s Sydney, thus contributing much material to the mythologising of that period. Gilmore died aged 97 and was accorded a state funeral.
Gilmore's image appears on the Australian $10 note, along with an illustration inspired by No Foe Shall Gather Our Harvest and, as part of the copy-protection microprint, the text of the poem itself. The background of the illustration features a portrait of Gilmore by the well known Australian artist Sir William Dobell.