Buache was trained under the geographer Guillaume Delisle, whose daughter he married, and whom he succeeded in the Académie des sciences in 1730. Buache was nominated first geographer of the king in 1729. He established the division of the world by seas and river systems. He believed in a southern continent, an hypothesis which was confirmed by later discoveries. In 1754, he published an "Atlas physique." He also wrote several pamphlets.
His nephew, Jean Nicolas Buache (born La Neuville-au-Pont, 15 February 1741; died Paris, 21 November 1825), was also a geographer of the king.