Although born in Sussex, Eardley always considered herself Scottish. She studied at Goldsmith's College of Art in London and the Glasgow School of Art. She divided her time between Glasgow (where she painted kitchen sink subjects, particularly street urchins) and the north-east fishing village of Catterline, just south of Aberdeen. The village and the sea, especially in stormy weather became her favourite subjects in her later years and the freely painted, often bleak and desolate works that resulted from this period are among the most powerful and individual landscapes in 20th-century British art.

After her early death from breast cancer, her ashes were scattered on the beach at Catterline. Her work is well represented in the Scottish National Gallery of Modern Art, Edinburgh and due to her early death, is sought keenly by collectors.