Mona Caird was born Alice Mona Alison in Ryde, a town on the British Isle of Wight, to a Scottish-German family. She began writing stories and plays in early childhood and was proficient in French and German.
In 1877, she married James Alexander Henryson-Caird, eight years her senior, a gentleman farmer with whom she had one son. He was supportive of her independence and lived at his homes in Scotland and Hampshire while she spent much of her time in London and travelling abroad. She participated in literary circles that included Thomas Hardy, and was active in the women's suffrage movement. She published her first two novels, Whom Nature Leadeth (1883) and One That Wins (1887), under the pseudonym G. Noel Hatton, but subsequent works were published under her own name. She rose rapidly to fame in 1888, after the Westminster Review printed her essay entitled "Marriage," and it became the focus of heated debate in the Daily Telegraph that drew a reported 27,000 letters from around the world. Mona Caird had called the institution of marriage a "vexatious failure," and advocated equality and autonomy for marriage partners. She continued to write essays on this radical idea and other women's issues that were collected into a volume called The Morality of Marriage and Other Essays on the Status and Destiny of Women (1897).
She also wrote fiction, much of which also focused on women's issues, then called the "New Woman" or "Modern Woman" type novel. Her most famous novel, The Daughters of Danaus (1894), became a feminist classic, as did her short story "The Yellow Drawing-Room" (1892). She was a member of the National Society for Women's Suffrage, the Women's Franchise League, the Women's Emancipation Union (WEU), and the London Society for Women's Suffrage, and participated in the Women’s Sunday march in Hyde Park in 1908 with 250,000 people. Among her later writings were an illustrated volume of travel essays, Romantic Cities of Provence (1906), and The Great Wave (1931), a science fiction novel.