Lebrun was made Third Consul following Napoleon Bonaparte's 18 Brumaire coup in the Year VIII (9–10 November 1799; "see French Consulate"). In this capacity, he took an active part in Napoleon's reorganization of the national finances and in the administration of France's "départements". He was made a member of the Académie des Inscriptions et Belles-Lettres in 1803, and in 1804, he was appointed Arch-Treasurer of the French Empire. From 1805 to 1806, he was governor-general of Liguria, during which time he completed its annexation by France.