Harriet Davidson was the eldest surviving daughter of Hugh Miller, a geologist and paleontologist, and his wife Lydia Falconer Fraser, both of whom were writers. Theirs was a literary household. Harriet read widely, and was educated in Edinburgh and in England. In Mr Oliphant's school in Edinburgh she won prizes for original poetry and elocution.

In 1856, when Davidson was seventeen, she was severely traumatised when her father shot himself. Her mother suffered a nervous breakdown, and Davidson stayed with her for a year while she recovered. She then attended Miss Taylor's school in London until she was twenty, learning riding, drawing and painting, singing and elocution.

In 1859 Davidson was holidaying with her mother in Germany when she met John Davidson, a minister of the Free Church; they were married in 1860. They came to South Australia in 1870 on the Carnaquheen, and John Davidson was pastor of Chalmer's Church, Adelaide for the next seven years. He was instrumental in the founding of the University of Adelaide in 1874, and in 1877 was appointed the first Hughes Professor of English Literature and Mental and Moral Philosophy. They lived at first at 'Fountain Villa' in East Terrace, Adelaide, where Davidson ran a school for her children and those of her friends, and following that, moved house a number of times.

Davidson had already published two religious and temperance novels before coming to Australia, and had contributed a poem, 'Summer' to Fraser's Magazine. She continued writing and reviewing after her arrival, contributing to the Register, the Evening Journal and the Adelaide Observer. Her daughter said of her, 'She was really an Intellectual. The joy of her life lay in the use of her wits. She was a fine talker, of the Victorian era, when talking was a fine art.' (Quoted in Margaret Allen, 'The Author's Daughter, the Professor's Wife', Jnl. of the Hist. Soc. of SA no. 27, 1999, p.120) She wrote across a number of genres: verse, fiction, essays, reviews and stories for children, her themes including religion, temperance and women's issues.

With two of her four children Davidson visited England in 1877-1878, partly to seek medical treatment. In 1880 she gave birth to a stillborn son, and from then her health began to deteriorate. John Davidson died at Glenelg in 1881 at the age of forty-seven, and Davidson died two years later at the age of forty-four.