Anna Harriet Edwards was born in India to a British military family. The family traveled around the Middle East during her childhood. At the end of 1849, Anna returned with her family to India, where in Poona she married her childhood sweetheart, Thomas Leon Owens -- he later contracted his second and last names as Leonowens. The couple moved to Australia, where Leonowens worked in the British colonial administration. Later they moved to Penang, where Thomas Leonowens died. Mrs. Leonowens became a teacher to support herself and her two surviving children. In 1862, she accepted a job teaching the many wives and children of King Mongkut of Siam (today's Thailand). Mrs. Leonowens sent her daughter Avis to school in England, and took her son Louis with her to Bangkok.
Her experiences were fictionalized by Margaret Landon in the 1944 bestselling novel Anna and the King of Siam, which inspired films and a musical play.
Mrs. Leonowens wrote her own memoirs of her time at the royal court as well as travel articles and books, and advocated for women's rights and the abolition of slavery. She visited and gave popular lecture tours in Aden, Australia, Singapore, Europe, Russia, the USA and Canada. Among other achievements, she co-founded the Nova Scotia College of Art and Design.