Privat de Molières studied at Oratorian schools in Aix, Marseilles, Arles and Angers. At the last of these schools he studied under Charles-René Reyneau from 1698 until 1699. He chose, against his parents wishes, an ecclesiastical life and entered the Congregation of the Oratory in 1699.
His first posts were teaching in schools belonging to the Congregation of the Oratory, first at Saumur, then at Juilly and finally at Soissons.
In 1704 he went to Paris to take up a more active scientific career. He studied mathematics and physics with Malebranche until 1715. In 1723 he was appointed to a chair at the Collège Royal to succeed Varignon.
Privat de Molières was elected to the Académie Royale des Sciences in 1721, and became a Fellow of the Royal Society of London in 1729.
He argued against Newton and for Descartes' view of physics although he knew Newton's to be the more precise. He attempted to bring Newton's calculations into the vortex theory of matter of Malebranche. Although his arguments were very effective, eventually Newtonian physics came to the fore in France.
Privat de Molières published Leçons de mathematiques (1726), a work on the principles of algebra and calculus. His Leçons de physique (1734-1739), was a four volume work based on his lectures at the Collège Royale.