The Flight to Varennes (night of June 20/21, 1791) was a significant episode in the French Revolution during which King Louis XVI of France, his wife Marie Antoinette, and their immediate family attempted unsuccessfully to escape from Paris in order to initiate a counter-revolution. Their destination was the fortress at Montmédy in northeastern France, a Royalist stronghold from which the king hoped to start a military campaign which would restore his rule. They were only able to make it as far as the small town of Varennes.

The incident was a turning point after which popular hostility towards the French monarchy as an institution, as well as towards the king and queen as individuals, became much more pronounced. The king's attempted flight provoked the charges of treason which ultimately led to his execution in 1793.