She was initially educated at Brighton and Hove High School. Afterwards she studied Latin and Greek at Newnham College, Cambridge, on a government scholarship. In 1883 she moved to London, where she started work as a governess, and then as the librarian at the People's Palace Library. Through her sister, Clementina, she met Dr. Richard Garnett, then the Keeper of Printed Materials at the British Museum, and his son Edward Garnett, whom she married in Brighton on 31 August 1889. Edward, after working as a publisher's reader for T. Fisher Unwin, William Heinemann, and Duckworth, went on to become a distinguished reader for the publisher Jonathan Cape. In the summer of 1891, then pregnant with her only child, she was introduced by Edward to the Russian exile Feliks Volkhovsky, who began teaching her Russian. He also introduced her to his fellow exile and colleague Sergius Stepniak and his wife Fanny. Soon after, Garnett began working with Stepniak, translating Russian works for publication; her first published translations were "A Common Story" by Ivan Goncharov, and "The Kingdom of God is Within You" by Leo Tolstoy. The latter was published while she was making her first trip to Russia in early 1894. After visits to Moscow and Saint Petersburg, she travelled to Yasnaya Polyana where she met Tolstoy; although the latter expressed interest in having her translate more of his religious works, she had already begun working on the novels of Turgenev and continued with that on her return home. Initially she worked with Stepniak on her translations; after his untimely death in 1895, Stepniak's wife Fanny worked with her. From 1906, her favourite amanuensis was a Russian girl, Natalie Duddington whom she had met in Russia and in whom she found "real intellectual companionship".