Nancy Bird was born in Kew, near Sydney in New South Wales. In her autobiography, she said she wanted to fly almost as soon as she could walk. During the Great Depression, she had to leave school at age 13 to go to work to assist her family, but began saving for flying lessons. In 1933, at age 17, against the opposition of her father, she began to take flying lessons from Sir Charles Kingsford Smith, the first man to fly across the mid-Pacific. In defiance of the traditional role of women of her time, she became a fully-qualified pilot at age 19 and the first female commercial aviator in Australia. With a small inheritance, she was able to buy her first aircraft, a de Havilland Gipsy Moth, and barnstormed around the country. In 1935, she was hired to operate an air ambulance service called the Royal Far West Children's Health Scheme. She had only basic navigation instruments and road maps, and often had to make hazardous landings in paddocks dotted with rabbit holes. In 1939, she married Charles Walton, an Englishman, and had two children. Her husband called her "Nancy-Bird" rather than "Nancy," and she became a household name as "Nancy-Bird Walton." At the outbreak of World War II, she began training women in piloting skills to assist the Royal Australian Air Force. In 1950, she founded the Australian Women Pilots' Association (AWPA) and served as its president for five years.
The National Trust of Australia declared her an Australian Living Treasure in 1997.
She appeared in the documentary film Flying Sheilas (2009) with seven other pioneering Australian female pilots. The title of her 2002 autobiography, My God, It's A Woman! was the response by a rancher, trapped on a remote property, when told that the pilot flying to his rescue was called Nancy.