Eliza Fletcher, née Dawson, was born at Oxton, near Tadcaster in Yorkshire, England. Her father Miles Dawson was a surveyor and small landowner and her mother Elizabeth Hill came from a Yorkshire gentry family. Her mother died 10 days after Eliza's birth. She grew into a beautiful and intelligent girl and later said she had a happy childhood. She was sent to the Manor School at York to be educated.
At age 17, she met Archibald Fletcher, a Scottish lawyer aged about 43, and carried on a literary correspondence with him for about a year. She married him in 1791 against her father's wishes, moved to Edinburgh, and had six children. She was part of a network of literary women that included Elizabeth Hamilton, Anne Grant, Joanna Baillie, Margaret Cullen, Mary Brunton, Anna Barbauld, and Catherine Cappe. She became active in philanthropy and social reform, and worked to improve the lives of the poor in Edinburgh. She also took a keen interest in politics and corresponded with Giuseppe Mazzini for years. Mrs. Fletcher's autobiography, originally printed in 1874 for private circulation, was edited by her daughter Mary, Lady Richardson, and published the following year.