She was the eldest of the five famous Mancini sisters, who along with two of their female Martinozzi cousins, were known at the court of Louis XIV of France as the Mazarinettes.

Laura was the eldest daughter of Baron Lorenzo Mancini, brother-in-law of Cardinal Mazarin through his wife Girolama Mazzarini.

The family resided in the Palais Royal in Paris, home of Queen Anne and her sons Louis XIV and Philippe, Duke of Orléans.

Laura married Louis at the Palais Royal in the French capital on 4 February 1651 and was thus became Duchess of Mercœur.

Buried in Paris, her husband retired from public life to become a cardinal, ensuring his children's upbringing to Laura's sister the Duchess of Bouillon.