Duniway was born Abigail Jane Scott near Groveland, Illinois, one of eleven children of John Tucker Scott and Anne Roelofson. She grew up on the family farm, and in 1852 she traveled the Oregon Trail with her family. As a young woman, she taught school in Cincinnati (now Eola), Oregon before marrying Benjamin C. Duniway on August 2, 1853. They had six children: Clara, Willis, Hubert, Wilkie, Clyde and Ralph.
After her husband's severe injury in 1862, Duniway supported the family by teaching and running a millinery in Albany, Oregon. She moved the family to Portland in May 1871 and began publishing a weekly newspaper The New Northwest. The paper was promoted as a human rights advocate, supporting education and women's suffrage. The National Women's Suffrage Association recognized Duniway as a leading women's advocate in the American West in 1886.
Duniway encountered personal setbacks such as poor health, money problems, and opposition from her brother Harvey W. Scott, who also edited a local paper, The Portland Oregonian. She persisted despite political opposition in the form of local resistance, the consistent failure of women's suffrage referendums on state ballots, and divisions with Eastern suffrage organizations. She and her newspaper actively supported the Sole Trader Bill and the Married Women's Property Act which, when passed, gave Oregon women the right to own and control property. Her persistence paid off in 1912 when Oregon became the seventh state in the Union to pass a women's suffrage amendment. Governor Oswald West asked her to write the proclamation for his signature. She was the first woman to register to vote in Multnomah County.
Duniway is buried at River View Cemetery in Portland.