Mary Quirk was educated at Rozelle Superior Public School. She worked as a domestic servant, until she married John Kelly on 28 September 1898, in Balmain, Sydney. They had a son and three daughters before he died in 1926. She then worked as a shop assistant and joined the Shop Assistants' Union of NSW.

On 9 February 1927 she married John Quirk, Labor MLA for Rozelle (1917-20, 1927-30) and Balmain (1920-27 and 1930-38). After he died in 1938, she was elected at the by election for Balmain in 1939. She and John Quirk were strong supporters of Lang. She was the first Labor woman and the second woman to be elected to the Legislative Assembly, and the galleries were filled with women on the day she was sworn in. She was especially concerned with the interests of housewives and industrial workers.

She lost preselection after two contested ballots in 1950 and was defeated by the official ALP candidate when she stood as an independent in June 1950. She became a director of the Sunshine Home for children. When she died, the premier James McGirr said that she had 'added a special dignity to our Parliament'.

Sources used to compile this entry: 'HERstory: Australian Labor Women in Federal, State and Territory Parliaments 1925-1994', Townsville, Qld., 1994; Blackley, Leanne L., 'Quirk, Mary Lilly May (1880 - 1952)', in Australian Dictionary of Biography Online, Australian National University, 2006, http://www.adb.online.anu.edu.au/biogs/A160051b.htm.