Pierre Prévost (3 March 1751 - 8 April 1839) was a Swiss philosopher and physicist. In 1791 he showed that all bodies radiate heat, no matter how hot or cold they are.

Son of a Protestant clergyman in Geneva, he was born in that city, and was educated for a clerical career. But he forsook it for law, and this too he quickly deserted to devote himself to education and to travelling. He became intimate with J. J. Rousseau, and, a little later, with Dugald Stewart, having previously distinguished himself as a translator of and commentator on Euripides. Frederick II of Prussia secured him in 1780 as professor of philosophy, and made him member of the Akademie der Wissenschaften in Berlin. He there became acquainted with Lagrange, and was thus led to turn his attention to physical science. After some years spent on political economy and on the principles of the fine arts (in connection with which he wrote, for the Berlin Memoirs , a remarkable dissertation on poetry) he returned to Geneva and began his work on magnetism and on heat. Interrupted occasionally in his studies by political duties, in which he was often called to the front, he remained professor of philosophy at Geneva till he was called in 1810 to the chair of physics. He died at Geneva in 1839.

Prevost published much on philology, philosophy, and political economy; but he will be remembered mainly for having published, with additions of his own, the Traite de physique of G. L. Le Sage , and for his enunciation of the law of exchange in radiation. His scientific publications included De l'Origine des forces magnetiques (1788), Recherches physico-mecaniques sur la chaleur (1792), and Essai sur le calorique rayonnant (1809).