Anatole Demidoff was a member of the Russian family that had acquired great wealth through mining and iron production in the 18th century. His date and place of birth cannot be determined with complete confidence, and published accounts provide conflicting information. His death certificate records his birthplace as St. Petersburg, and gives his age as 57. Other sources record the place of his birth as Florence.
Anatole was educated principally in Paris, where his father, Nicolas, had taken the family after Napoleon's defeat. After his father's death in 1828, Anatole returned to the villa in San Donato, near Florence, that Nicolas had begun building, and proceeded to enlarge it, eventually transforming most of it in 1836 into a workshop for the manufacture of silks. He continued to live mainly in Paris, travel widely, and enlarge the art collection begun by his father. In 1837 he organized an expedition to the Crimea and South Russia of French artists, journalists, scientists, and archaeologists, the result of which were various publications that appeared in the 1840s describing in detail the journey, and the area's cultural and natural history.
On 1 November 1840, Anatole married Contessa Mathilde Bonaparte de Monfort, daughter of Jérôme Bonaparte [1784-1860], King of Westphalia, by his second wife, Catherine of Württemburg [1782-1835], and niece of Napoleon I. The marriage, however, failed, and in 1848 Tsar Nicholas I arranged the terms of the separation. Demidoff spent much of the rest of his life traveling, but until he returned to Paris in around 1860, his life centered on the villa and collection in San Donato, for which he continued to purchase works of art. Like his father, he also established along the way numerous charitable institutions, and created a prize of 5,000 rubles at the Academy of Sciences in St. Petersburg for the best work published each year in the Russian language.
After Anatole's death in Paris in 1870, the art collection and title of Prince of San Donato was inherited by his nephew, Paul Demidoff [1839-1885], the son of his older brother, Paul Nikolayevich Demidov [1798-1840].