At the end of 1716 he left the Jesuits to join the army, but soon tired of military life, and returned to Paris in 1719, apparently with the idea of resuming his novitiate. He is said to have travelled in the Netherlands about this time; in any case he returned to the army, this time with a commission. Some biographers have assumed that he suffered some of the misfortunes assigned to his hero Des Grieux. Whatever the truth, he joined the learned community of the Benedictines of St Maur, with whom he found refuge, he himself says, after the unlucky termination of a love affair. He took his vows at Jumièges in 1721 after a year's novitiate, and in 1726 took priest's orders at St Germer de Flaix. He spent seven years in various houses of the order, teaching, preaching and studying. In 1728 he was at the Abbey of Saint-Germain-des-Prés, Paris, where he was engaged on the Gallia Christiana, the learned work undertaken by the monks in continuation of the works of Denys de Sainte-Marthe, who had been a member of their order. His restless spirit made him seek from the Pope a transfer to the easier rule of Cluny; but he left the abbey without leave (1728), and, learning that his superiors had obtained a lettre de cachet against him, fled to England.
In London he acquired a wide knowledge of English history and literature, as can be seen in his writings. Before leaving the Benedictines Prévost had begun perhaps his most famous novel, Mémoires et aventures d’un homme de qualité qui s’est retiré du monde, the first four volumes of which were published in Paris in 1728, and two years later at Amsterdam. In 1729 he left England for the Netherlands, where he began to publish (Utrecht, 1731) a novel, the material of which, at least, had been gathered in London Le Philosophe anglais, ou Histoire de Monsieur Cleveland, fils naturel de Cromwell, écrite par lui-même, et traduite de l'anglais (Paris 1731-1739, 8 vols., but most of the existing sets are partly Paris and partly Utrecht). A spurious fifth volume (Utrecht, 1734) contained attacks on the Jesuits, and an English translation of the whole appeared in 1734.
Meanwhile, during his residence at the Hague, he engaged on a translation of De Thou's Historia, and, relying on the popularity of his first book, published at Amsterdam a Suite in three volumes, forming volumes v, vi, and vii of the original Mémoires et aventures d’un homme de qualité. The seventh volume contained the famous Manon Lescaut, separately published in Paris in 1731 as Histoire du Chevalier des Grieux et de Manon Lescaut. The book was eagerly read, chiefly in pirated copies, being forbidden in France. In 1733 he left the Hague for London in company with a lady whose character, according to Prévost's enemies, was doubtful. In London he edited a weekly gazette on the model of Joseph Addison's Spectator, Le Pour et contre, which he continued to produce, with short intervals, until 1740.
In the autumn of 1734 Prévost was reconciled with the Benedictines, and, returning to France, was received in the Benedictine monastery of La Croix-Saint-Leufroy in the diocese of Évreux to pass through a new, though brief, novitiate. In 1735 he was dispensed from residence in a monastery by becoming almoner to the Prince de Conti, and in 1754 obtained the priory of St Georges de Gesnes. He continued to produce novels and translations from the English, and, with the exception of a brief exile (1741-1742) spent in Brussels and Frankfurt, he resided for the most part at Chantilly until his death, which took place suddenly while he was walking in the neighbouring woods. The cause of his death, the rupture of an aneurysm, is all that is definitely known. Stories of crime and disaster were related of Prévost by his enemies, and diligently repeated, but appear to be apocryphal.
Prévost's other works include: