In 1653 Laura, her older sister Anna Maria (1637 – 4 February 1672) and their widowed mother moved to Paris to live with her maternal uncle, Cardinal Mazarin.

[1][2] The Cardinal thought of marrying Laura with Charles Emmanuel II, Duke of Savoy, but then he began to plan her marriage to Alfonso d'Este, heir of the Duchy of Modena.

Finally, on 30 May the marriage per procura was concluded at the Château de Compiègne, in which the groom was represented by Prince Eugene Maurice of Savoy, Count of Soissons.

Her second child, a daughter, was born prematurely six months later, on 5 October, but survived: named Maria Beatrice Eleonora Anna Margherita Isabella, she later became Queen consort of England, Scotland and Ireland as the second wife of King James II and VII.

Nine days later, on 14 October, Laura's father-in-law died and her husband became Duke of Modena and Reggio under the name of Alfonso IV and with the rank of generalissimo led the army of the French kingdom in Italian lands.

The new Duchess consort gave birth her third and last child less than two years later, on 6 March 1660: a second son, also named Francesco after his paternal grandfather, who eventually succeeded his father as Duke of Modena and Reggio.

She had a firm and strong-willed character, which she showed not only in the fight against crime in her son's possessions, but also in relation to the local nobility, whose representatives tried to take advantage of the Duke's infancy for their own interests.

At the same time, she spent a lot of money on the repair of the ducal palace and the construction of the convent of the Visitation Sisters, in Modena, as well as for the reconstruction of the Church of St. Augustine.

During her absence, the Dowager Duchess entrusted her son to the care of ministers; however Marquess Cesare Ignazio d'Este, taking advantage of the situation, was able to win over the young duke and turn him against his mother.

Laura returned to Modena on 5 March 1674, and the next day, celebrating his fourteenth birthday, Francesco II dissolved the regency council and assumed his personal rule.

Cesare Ignazio d'Este persuaded Francesco II to not answer Laura's letters, who asked him to return the property bequeathed to her by her uncle, Cardinal Mazarin.