Born around 1665 to Antoine de Brouilly, Marquis de Piennes, and Françoise Godet, Marie-Rosalie was known as Mademoiselle de Brouilly before her marriage.
Not too much is known about the time before her marriage, but it appears that Mademoiselle de Brouilly became a short-time mistress of Louis XIV in 1682. He was in his early forties, she probably around seventeen. How long the affair lasted is not entirely clear.
On March 28 in 1685, Marie-Rosalie married Alexis-Henri de Châtillon, who was titled Marquis de Châtillon the same year. This gentleman served as premier gentilhomme and captain of the guards to Monsieur. The couple had five children, of which two died in infancy.
Now styled Marquise de Châtillon, Marie-Rosalie entered the service of Madame as dame d’atour in 1689 and the sky darkened a little. According to Saint-Simon, the Marquis, a former favourite of Monsieur, married her for love, but what Saint-Simon called the most beautiful pair of the court began to argue with each other. One of these arguments led to separation and not wanting to see each other again. Dangeau noted in his diary that Alexis-Henri kept his wives property, their shared apartment was divided and Marie-Rosalie was entirely dependant on what Monsieur and Madame granted her as income. Both saw each other nearly every day, since they both served in the same household, but it did not improve their relationship.
After seventeen years in service of Madame, Madame de Châtillon decided to retire and asked her mistress for permission to do so in 1706. It was granted, but the Marquise remained another two years at court, keeping her apartments at the Palais-Royal and Versailles, until the latter was given to the Princesse de l’Espinoy.
Marie-Rosalie died on September 12 in 1735.