He was a pupil of the Jesuits at the College de Clermont (now Louis-le-Grand), Paris; then a student at Caen. For a time he studied law at the College d'Harcourt. He soon, however, took to arms, and in 1629 went with Marshal Bassompierre to Italy. He served through great part of the Thirty Years' War, distinguishing himself at the siege of Landrecies (1637), when he was made captain. During his campaigns he studied the works of Montaigne and the Spanish and Italian languages.
In 1639 he met Gassendi in Paris, and became one of his disciples. He was present at Rocroi, at Nördlingen, and at Lerida. For a time he was personally attached to Condé, but offended him by a satirical remark and was deprived of his command in the prince's guards in 1648. During the Fronde, Saint-Évremond was a steady royalist. The duke of Candale (of whom he has left a very severe portrait) gave him a command in Guienne, and Saint-Évremond, who had reached the grade of maréchal de camp, is said to have saved 50,000 livres in less than three years. He was one of the numerous victims involved in the fall of Fouquet. His letter to Marshal Créqui on the peace of the Pyrenees, which is said to have been discovered by Colbert's agents at the seizure of Fouquet's papers, seems a very inadequate cause for his disgrace.
Saint-Évremond fled to Holland and to England, where he was kindly received by Charles II and was pensioned. After James II's flight to France Saint-Évremond was invited to return, but he declined. Hortense Mancini, the most attractive of Mazarin's attractive group of nieces, came to England in 1670, and set up a salon for love-making, gambling and witty conversation, and here Saint-Évremond was for many years at home. He died on the 29th of September 1703 and was buried in Westminster Abbey, where his monument still is in Poet's Corner close to that of Prior.
Saint-Évremond never authorized the printing of any of his works during his lifetime, though Barbin in 1668 published an unauthorized collection. But he empowered Des Maizeaux to publish his works after his death, and they were published in London (2 vols., 1705), and often reprinted. His masterpiece in irony is the so-called Conversation du maréchal d'Hocquincourt avec le père Canaye (the latter a Jesuit and Saint-Évremond's master at school), which has been frequently classed with the Lettres provinciales.
His Œuvres meslées, edited from the manuscripts by Silvestre and Des Maizeaux, were printed by Jacob Tonson (London, 1705, 2 vols.; 2nd ed., 3 vols., 1709), with a notice by Des Maizeaux. His correspondence with Ninon de l'Enclos, whose fast friend he was, was published in 1752; La Comédie des académistes, written in 1643, was printed in 1650. Modern editions of his works are by Hippeau (Paris, 1852), C Giraud (Paris, 1865), and a selection (1881) with a notice by M. de Lescure.