Personal life
On 12 May 1834, he was married to Marthe Augustine de Saint-Georges de Vérac (1812–1884), the youngest daughter of Euphémie de Noailles (a daughter of Louis Marc Antoine de Noailles, Viscount of Noailles) and Olivier de Saint-Georges de Vérac, Marquis de Vérac, a maréchal de camp who served as governor of the Château de Versailles. Together, they were the parents of eleven children, including:
Charles-Albert-Marie Costa, Marquis de Beauregard (1835–1909), who married Emilie Pourroy de l'Aubérivière de Quinsonas (1841–1929), a daughter of the Adolphe de Pourroy de l'Aubérivière, 4th Marquis de Quinsonas.
Camille-Josselin-Marie-Victor Costa, Marquis de Beauregard (1836–1916), who married Béatrix Marie Antoinette Budes de Guébriant (1840–1898) in 1864.
Count Armand-Marie-Henri-Olivier Costa de Beauregard (1838–1921), the former secretary of the embassy.
Count Gabriel-Marie-Paul Costa de Beauregard (1839–1901), who married his cousin Marie-Pauline Herminie de Rougé, a daughter of Count Adolphe de Rougé and Marie de Saint-Georges de Vérac, in 1869.
Count Camille-Jean-Adolphe-Marie Costa de Beauregard (1841–1910), Canon of Chambéry.
Élisabeth Gasparine Marie Costa de Beauregard (1842–1843), who died young.
François-Marie-Pantaléon Costa de Beauregard (1844–1844), who died young.
Félicie-Louise-Marie Costa de Beauregard (1845–1893), who married Henri Fernand Jules de Prunelé, Marquis de Prunelé (1836–1897) of the Château de Trécesson in 1866.
Alix-Fernande-Marie Costa de Beauregard (1847–1915), a member of the Daughters of Charity.
Count Charles-Albert-Marie-Olivier Costa de Beauregard (1848–1870), a Second Lt. with the Lancers who died at the Battle of Sedan during the Franco-Prussian War.
Marie-Antoinette-Charlotte-Stéphanie (1850–1875), who married Arthur-Ettiene de Lancrau, Count de Bréon (1843–1904), in 1872.
Beauregard died on 19 September 1864 at La Motte-Servolex. He was succeeded in the marquisate by his eldest son, Charles.
