La Beaumelle was a brilliant student in Alès and stayed there for eight years (1734-42). He joined the Reformed Church in 1744. In 1745 he went to Geneva; the next year he joined the Freemasons. In 1747 he went to Denmark and wrote Traité sur la tolérance, and L'Asiatique tolérant, ou traité à l'usage de Zeokinizul, roi des Kofirans, surnommé le Chéri published in Amsterdam in 1749. Then he was appointed as professor of French literature at the University of Copenhagen. In 1751 he received almost simultaneously with Voltaire, an invitation by the Prussian King Frederick the Great to come to Sanssouci in Potsdam. Beaumelle fell out with "La Voltaire" and he went back to Paris, visiting Gotha and Frankfurt, in 1752 with deadly hatred of Voltaire.
Because of his "Notes sur le siècle de Louis XIV", La Beaumelle was arrested on 24 April and imprisoned in the Bastille till 12 October 1753. In 1755 he went to Holland and met with Henri de Catt. Soon after his return to Paris, the publication of his Mémoires de la Maintenon brought him again for a year in jail (September 1757). Voltaire seems both times to have been involved. After his release, La Beaumelle settled down as a freelance writer in Toulouse (1759), but without permission to leave the Languedoc. La Beaumelle got involved in the case of Jean Calas. In 1764 he married Rose-Victoire Lavaysse. Their daughter Aglaé was born in 1768. Around 1770 King Louis XV appointed him at the Bibliothèque Royale, and granted him a pension.
Most of his writings bear a polemical, pamphlet-like character or speculate (as contained in the "Memoirs of Madame de Maintenon") on the audience's curiosity. His best writing is unquestionably "Reponse au Supplément du siècle de Louis XIV, ou Lettres à Voltaire" (1754, 1763), by wit, spirit and energy the most distinguished. His worst is the "Commentaire sur la Henriade" (1775), a very model of inept, pathetic criticism.