Though due to legal obligations he still had some affiliation with L'Année littéraire, Fréron took up writing and editing his paper L'Orateur du Peuple. In it, he wrote radical denunciations of counter-revolutionaries much like those written by Jean-Paul Marat and Camille Desmoulins, and in fact the three of them aided each other in editing their papers. His first real taste of rabble-rousing came in the form of collaboration with Desmoulins to incite the storming of the Bastille. Soon after, he was elected as representative to the Bonne-Nouvelle district of the newly formed Paris Commune, where it seems he was minimally active before returning to his role as a journalist. He acted as a collaborator for L’Ami des citoyens for a brief period before starting his own paper L'Orateur du Peuple, under the pseudonym Martel, which consisted of 8 pages and was distributed every other day, with Marcel Enfantin serving as editor. Aside from his writings in his paper, he openly collaborated with Marat and agreed to fund and write half of Desmoulins paper. In June 1790, Marcel Enfantin was arrested for "provable conspiracy against liberty" because the authorities believed him to be Martel. In response, Fréron wrote: Also, Fréron's relationship with Desmoulins brought him to the cause of the Cordeliers and prompted his involvement with the attack on Tuileries palace of 1792. In September, Fréron was elected to the NationalConvention for the département of Seine, and voted in favor of Louis XVI's execution. Fréron served as a Représentant en mission to Provence, Marseilles, and Toulon between 1793 and 1794 together with Paul Barras.
He was charged with establishing the Convention's authority in the south during the Toulon rebellion. Fréron remained infamous as an enforcer of the Reign of Terror but came into contact with Napoleon Bonaparte, still just a young artillery officer, who had been stationed there. Augustin Robespierre and Antoine Christophe Saliceti, two representatives on mission, responded favourably to Napoleon's request to seize the peninsula fort from the British and install artillery on a promontory overlooking the bay in order to fire on the British fleet at anchor. An infantry attack led by Bonaparte was repelled, due chiefly to Carteaux lowering the number of men allocated to Napoleon for the attack. Fréron, despite quarrelling with Bonaparte and threatening him with execution, eventually gave him his backing against Carteaux. He subsequently attempted to curtail Napoleon's career by insuring he would not command another larger attack on the British fort that was being planned, posting him to command the reserves instead. However, as this new attack faltered, Napoleon led the reserves forward without orders and seized the British fort. Napoleon had previously introduced Fréron to his sister Pauline Bonaparte with whom he had a relationship until Pauline was married off to General Charles Leclerc in 1797.
Nonetheless, both he and Barras joined the Thermidorian Reaction in its clash with Robespierre; L'Orateur du Peuple became the mouthpiece of anti-Jacobins, and Fréron incited the Muscadins to attack the sans-culottes with clubs. He brought about the accusation of Antoine Fouquier-Tinville, and of Jean-Baptiste Carrier, and the arrest of the last Montagnards. Being sent by the Directory on a mission of peace to Marseilles he published in 1796 Mémoire historique sur la réaction royale et sur les malheurs du midi. He was elected to the Council of the Five Hundred, but not allowed to take his seat. Failing as suitor for the hand of Pauline Bonaparte, in 1801 he was sent by Napoleon, now first consul, to Saint Domingue and died there from yellow fever in 1802. General Charles Leclerc, who had married Pauline Bonaparte, also received a command in Saint Domingue in 1801, and died the same year.
