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Saxe-Hildburghausen was one of the duchy of the present State of Thuringia in Germany. It was located in the southern side.
The independent duchy existed from 1680 to 1826.

To the duchy belonged district and city Hildburghausen,District and city of Heldburg, the District and city of Eisfeld, the District of Veilsdorf and the half of the District of Schalkau and later Königsberg and Sonnefeld, as well. In 1699, when Albert V, the Duke of Saxe-Coburg died isputes arose over the inheritance, because he had not any surviving descendants. 15 years later, Saxe-Hildburghausen agreed to exchange the District of Schalkau for parts of Saxony – a piece of the former Duchy of Saxe-Römhild, the District of Behrungen, including the winery, and the monastery estate of Milz as well as the former properties of the Echter family of Mespelbrunn.

In 1806, Saxe-Hildburghausen gained its full sovereignty as the Duchy of Saxe-Hildburghausen, because the dissolution of the Holy Roman Empire. In 1868, four districts were established in the duchy of Saxe-Meiningen. Hildburghausen was one of these districts, with boundaries very similar to those of the former duchy. It remained almost unchanged until 1993.