The Constitution of 1793 (French: Acte constitutionnel du 24 juin 1793), also known as the Constitution of the Year I or the Montagnard Constitution, was the second constitution ratified for use during the French Revolution under the First Republic. Designed by the Montagnards, principally Maximilien Robespierre and Louis Saint-Just, it was intended to replace the constitutional monarchy of 1791 and the Girondin constitutional project. With sweeping plans for democratization and wealth redistribution, the new document promised a significant departure from the relatively moderate goals of the Revolution in previous years.

However, the Constitution's radical provisions were never implemented. The government placed a moratorium upon it, ostensibly because of the need to employ emergency war powers during the French Revolutionary War. Those same emergency powers would permit the Committee of Public Safety to conduct the Reign of Terror, and when that long period of violent political combat was over, the constitution was invalidated by its association with the defeated Robespierre. In the Thermidorian Reaction, it was discarded in favor of a more conservative document, the Constitution of 1795.