Born in Le Havre, Ancelot became a clerk in the admiralty, and retained his position until the Revolution of 1830. In 1816 his play Warwick was accepted by the Théâtre Français, but never produced, and three years later a five-act tragedy, Louis IX, was staged. Three editions of the play were speedily exhausted; it had a run of fifty representations, and brought him a pension of 2000 francs from Louis XVIII. His next work, Le Maire du palais, was played in 1825 with less success; but for it he received the cross of the Légion d'honneur. In 1824 he produced Fiesque, a clever adaptation of Schiller's Fiesco. In 1828 appeared Olga, ou l'orpheline russe, the plot of which had been inspired by a voyage he made to Russia in 1826. About the same period he produced in succession Marie de Brabant (1825), a poem in six cantos; L'Homme du monde (1827), a novel in four volumes, afterwards dramatized with success; and in 1829 a play, Elisabeth d'Angleterre.
By the Revolution of July 1830 he lost at once his royal pension and his office as librarian at Meudon; and he was chiefly employed during the next ten years in writing vaudevilles and light dramas and comedies. A tragedy, Maria Padilla (1838), gained him admission to the Académie française in 1841. Ancelot was sent by the French government in 1849 to Turin, Florence, Brussels and other capitals, to negotiate on the subject of international copyright; and the treaties which were concluded soon after were the result, in a great measure, of his tact and intelligence.