Maria Jane McIntosh was born in 1803 in Sunbury, Georgia, to Mary Moore (Maxwell) and Lachlan McIntosh, the descendant of a prominent Scottish family and a wealthy plantation owner and lawyer who died when Maria was just a few years old. McIntosh was educated at home by her mother and at two schools: a coeducational academy in Sunbury and Baisden's Bluff Academy in McIntosh County. After her mother died in 1823, McIntosh began managing the plantation. In 1835 she sold the property and moved to New York to live with a half brother, naval Captain James McKay McIntosh. She invested her fortune in securities but lost it in the Panic of 1837.
McIntosh's financial crisis led her to attempt a writing career, beginning with a series of moral children's stories that were published using the pseudonym "Aunt Kitty." By the early 1840s she had turned to writing moral fiction for adults and novels that Nina Baym classifies as "woman's fiction," publishing anonymously until 1846. McIntosh was a prolific writer, and her novels were successful enough, appearing both in American and British editions, to afford her an independent living.
McIntosh spent 1859 living in Geneva, Switzerland, with the wife of a nephew, John Elliott Ward. After she returned to New York, she taught at a school run by Henrietta B. Haines. After publishing her final novel, Two Pictures; or, What We Think of Ourselves, and What the World Thinks of Us ( 1863), she held for a time a fashionable salon in New York. After suffering a yearlong illness, McIntosh died at the home of her niece and namesake, Maria McIntosh Cox (who was also a writer), in Morristown, New Jersey, on February 25, 1878.