Born in Paris, he was in the retinue of the comte d'Artois (future King Charles X), and became an officer in a cuirassier regiment. He served in the American War of Independence, was deputy to the Estates-General of 1789, which subsequently became the National Assembly and National Constituent Assembly. As the Assembly began to divide into factions, Lameth, a constitutional monarchist, was identified with the Feuillants. Since the French Revolution moved toward a Republic, he emigrated.
He returned to France under the Consulate, and was appointed governor of Würzburg (in the Duchy of Würzburg) under the First Empire. In 1814, he rose to the rank of Lieutenant General. Like his brother Alexandre Lameth (but unlike his other one, Théodore de Lameth), after the Bourbon Restoration, Charles joined the Bourbon camp, succeeding Alexandre as deputy in 1829. In the final years of his life, he was nonetheless a noted supporter of the July Monarchy.