Duke of Mouchy (Spanish: Duque de Mouchy) was a hereditary title in the peerage of Spain, accompanied by the dignity of Grandee and granted in 1747 by Ferdinand VI to Philippe de Noailles, a French military officer. After failure of the 1st Duke's successors in inheriting the dukedom through the established legal procedures, the title expired in the Kingdom of Spain. Withal, it was bestowed by Louis XVIII of France on the eldest son of the 1st Duke in 1817 as a title in the French peerage.

The Dukedom of Mouchy has since been held by members of a cadet branch of the Noailles family. Owing to the political system of France, a republic, the title is unrecognised (as with all titles). The title could have nonetheless been rehabilitated legally in Spain prior to 1988, when a legal reform was made prohibiting titles with more than forty years of disuse from being revived.