At the age of 16, Gabrielle was betrothed to Jules François Armand, comte de Polignac, marquis de Mancini (1746–1817), whom she married on 7 July 1767, a few months short of her 18th birthday. Polignac's family had a "well-bred" ancestry similar to Gabrielle's family, and was in equally uncomfortable financial straits. At the time of his marriage, Polignac was serving in the "Régiment de Royal Dragons" ("1er régiment de dragons"), on an annual salary of 4,000 livres. Within a few years of the marriage, Jules and Gabrielle had two children: a daughter Aglaé and a son. Two more sons followed several years later, including Jules, prince de Polignac, who became the prime minister of France in 1829, under Charles X.