Annie Keary was born in Bilton, near Wetherby in Yorkshire, England, to William Keary, an Irish clergyman and former army chaplain, and his wife Lucy Plumer. She was educated at home and her father gave her much of the information about Ireland that she would later use in her writing. Her younger sister Eliza Keary also became a writer and poet, and the two traveled together in Egypt and collaborated on several books. In 1848, Annie went to keep house for a widowed older brother with three children in Staffordshire, where she stayed for six years. Her first children's book appeared in 1856, a year after her father's death. Her third book, The Heroes of Asgard (1857), was the first of three that she co-wrote with Eliza. She also wrote educational books for children such as Early Egyptian History (1861) and The Nation Around (1870). In 1859, she began publishing fiction for adults with Through the Shadows (1859). Castle Daly: The Story of an Irish Home Thirty Years Ago (1875) was reprinted several times up to the 1880s. She worked with Eliza and their sister Maud on Enchanted Tulips and Other Verses for Children, which was not published until 1914. Her final novel, A Doubting Heart (1879), was left unfinished at her death and was completed by a friend, Mrs. K. Macquoid. She was in frail health for much of her life and died at age 54 in 1879. Her sister Eliza wrote a memoir about her.