Left an orphan in her early years, she was cared for by her maternal uncle, Philippe de Coulanges, Abbot of Livry. She studied Italian and Spanish and acquired a classical education. In 1644 she married the Marquis Henri de Sévigné, by whom she had two children: in 1646 Françoise, who married in 1669 the Count of Grignan, later lieutenant-general of the King in Provence; and in 1648 Charles, who gave her some distress through his dissolute life. Widowed in 1651, she settled in Paris, where she devoted herself to the care of her children without neglecting society, with some attendance at court. Some disagreements of a personal nature with her daughter and a few hints of scandal, quickly suppressed, constituted the major misfortunes of her life, which was that typical of noble Frenchwomen of the 17th century, accompanied by the practice of the Catholic faith with sincerity and assiduity.
Her literary sensibility was formed essentially on Corneille, Molière, and La Fontaine. She held Ariosto and Tasso in high esteem, as well as St. Augustine and Pascal. Her work, consisting of a vast epistolary corpus (over 1,500 letters, mostly addressed to her daughter), is of exceptional interest for the history of the customs of the aristocratic society of her time and for its intrinsic artistic merits, thanks to a keen psychological insight and a lively, sometimes finely humorous, portrayal of situations and figures. For her exemplary style she was considered, almost on a par with La Fontaine and Molière, among the greatest French writers of the 17th century. Endowed with a firm morality, she was not, however, entirely free from a certain hardness of heart, a lack of human compassion that sometimes made her insensitive to misfortunes not concerning her aristocratic circle.