Ordained in Paris, France in 1788, he joined the Society of Priests of Saint Sulpice on 20 March 1790. As superior of the seminary at Issy, France, he withdrew to Bordeaux, France during the French Revolution, and in 1794 went to the United States. He was president of Georgetown College from 1796 to 1799, and he founded Saint Mary’s College in Baltimore, Maryland, acting as its first president. On 18 August 1812 he was appointed Apostolic Administrator of Louisiana and the Floridas, which had been under the jurisdiction of Bishop Carroll after the accession of Louisiana to the United States in 1801, the first bishop having been the Spaniard, Right Reverend Louis Pefialver y Cardenas. In 1815 the administrator celebrated a Mass of thanksgiving for the victory of General Jackson over the British, greeting the general at the door of the New Orleans cathedral. Consecrated bishop of Louisiana and the Floridas on 18 September 1815 in Rome, Italy. He took up his residence in Saint Louis, Missouri, and having brought out several Vincentians from Rome he established a seminary under their charge at “The Barrens,” about 80 miles from Saint Louis. In 1818 the Religious of the Sacred Heart made their first foundation in America, at Saint Charles, moving soon after to Florissant, where the Jesuits also were established in 1823. Founded the Saint Louis Latin Academy, the nucleus of the present Saint Louis University. He had a share in the organization in 1822 of the Society for the Propagation of the Faith, founded, 1820, by Venerable Pauline-Marie Jaricot of Lyons. After the appointment of Right Reverend Joseph Rosati as coadjutor, with residence in Saint Louis, in 1823, Bishop Dubourg established himself at New Orleans. He resigned his difficult see on 1 February 1825, discouraged by the opposition of trustees. He had organized about twenty parishes. Vicar Apostolic of Mississippi on 19 August 1825. He was transferred to the Diocese of Montauban, France on 13 August 1826. Archbishop of Besancon, France on 3 February 1833.