Plessix-Balisson (; ) is a former commune in the Côtes-d'Armor department of Brittany in northwestern France. On 1 January 2017, it was merged into the new commune Beaussais-sur-Mer.
With an area of only eight hectares, Plessix-Balisson was the smallest commune of the region and the second smallest in France, after Castelmoron-d'Albret.