Duc de Piney (Duke of Piney) was a title in the Peerage of France. The holders were also sometimes called duc de Luxembourg, after the House of Luxembourg, from whom they were descended.
The duchy-peerage was created in 1581 for François de Luxembourg, third son of Antoine de Luxembourg, Count of Ligny and Brienne. He died in 1613 and was succeeded by his son.
Henri de Luxembourg (1583-1616), second duke, was father of Marguerite-Charlotte de Luxembourg (1607-1680), heiress to the title. She married firstly, Léon d'Albert de Luynes (1582-1630), who became third duc de Piney jure uxoris; he was the younger brother of Charles d'Albert, duc de Luynes. Their son, Henri-Léon d'Albert de Luxembourg (1630-1697), fourth duke, resigned the peerage in 1661. His mother simultaneously resigned it to her daughter by her second marriage (the fourth duke's half-sister), Madeleine-Charlotte de Clermont de Luxembourg (1635-1701). She was the daughter of Charles-Henri de Clermont-Tonnerre (died 1674).
Madeleine-Charlotte was married in 1661 to François-Henri de Montmorency (1628-1695), comte de Luxe et de Bouteville; he became fifth duc de Piney jure uxoris and later a Marshal of France. Their son Charles-François de Montmorency-Luxembourg (1662-1726), sixth duc de Piney, had previously been created duc de Beaufort, later de Montmorency. He was father of Charles-François-Frédéric de Montmorency-Luxembourg (1702-1764), seventh duc de Piney and second duc de Montmorency, who also became a Marshal of France. At his death the dukedom of Montmorency passed to the family of his grand-daughter, while the lands of Piney were purchased by Anne-Charles-Sigismond de Montmorency-Luxembourg (1737-1803), marquis de Royan, who therefore became duc de Piney. He was the son of Charles-Anne-Sigismond, duc d'Olonne (1721-1777) and grandson of the last duke's first cousin and heir-male Charles-Paul-Sigismond, duc de Bouteville (1697-1785); both these men had declined the peerage. His son Charles-Emmanuel-Sigismond de Montmorency-Luxembourg (1774-1861) was the last holder of the title, though the last male member of the Montmorency-Luxembourg family was Anne-Edouard-Louis-Joseph (1802-1878), duc de Beaumont.