In December 1618, Louis XIII named her to the newly created post of surintendante of the queen's household, prompting the première dame du palais, the much older and now outranked widow of the Connétable de Montmorency, to resign in protest.

[7] On Christmas night 1620, attended by the queen, Marie de Rohan gave birth to Luynes' son and heir, Louis Charles, named after the king and his father.

Paris church bells were rung to celebrate the event, and cannon were fired at the medieval Château de Caen, where the king and the duke were staying.

Their son was baptised in Paris with Louis XIII as godfather and the king's mother, Marie de Médicis, as godmother.

His daughter Jeanne Baptiste, simultaneously Marie's granddaughter and niece, was the mistress of Victor Amadeus II of Sardinia and ancestress of the Savoy kings of Italy.

The now Dowager Duchess of Luynes inherited the Duke's Paris townhouse (hôtel particulier) on the rue Saint-Thomas-du-Louvre [fr].

In her attempts to regain her lost position, she provoked or encouraged the conspiracies of the court, such as the Buckingham affair (1623–24) that compromised the Queen, which she instigated with the connivance of her English lover, Henry Rich, later created Earl of Holland, and of the highest-ranking aristocrats against Richelieu, such as her complicity in the Chalais conspiracy involving her lover, the comte de Chalais, that she set up in 1626, with the unlikely intention of replacing Louis XIII with his brother, Gaston d'Orléans.

She was involved in the conspiracy of the comte de Soissons (1641) and at the death of the king, a clause in the testament of succession forbade the return to France of the duchesse; a decision of the Parlement of Paris was required to break the will.

Gaetano Donizetti's tragic opera Maria di Rohan, which debuted at the Kärntnertor theater in Vienna on 5 June 1843, followed by a success in Paris in November, was freely based on the conspiracy of Chalais.