He was the son of Marshal of France Victor-Francois, Duc de Broglie, created, by Emperor Francis I, Prince of the Holy Roman Empire, a title which was to be hereditary in the family.

King Frederick William II of Prussia received the duke with marked distinction and granted to the young prince a provostship in the cathedral chapter of Posen.

Maurice returned to France in 1803, and the steps he took to recover some family property not yet sold brought him to the attention of Napoleon, who invited him to his court and named him his almoner.

At first only two, d'Aviau, Archbishop of Bordeaux, and de Broglie, Bishop of Ghent, rejected it; but subsequently, only four members were for the pure and simple acceptance of the decree.

Arrested on 12 July 1811, de Broglie was cast into the dungeon at Vincennes and kept in close confinement for more than four months, without outside communication, and without books or writing materials.

De Broglie also appealed to Pius VII, and the pontiff, on 16 May 1816, sent an official note to the minister of the Low Countries residing in Rome, stating that the Belgian Constitution contained statements contrary to Catholicism, that the opposition of the bishops could not in justice be reproved, and that no oath opposed to conscience should be imposed.