The Duchy of Carinthia is a duchy located in southern Austria and parts of northern Slovenia.

It was separated from the Duchy of Bavaria in 976, and was the first newly created Imperial State after the original German stem duchies.Carinthia remains a part of the Holy Roman Empire until its dissolution in 1806, and a crown land of Austria-Hungary until 1918.

By the Carinthian Plebiscite in October 1920, the main area of the duchy forms the Austrian state of Carinthia.

A small southeastern part (the present-day region of Slovenian Carinthia) is included in the newly created Kingdom of Serbs, Croats and Slovenes.

The southwestern Canal Valley (Val Canale) with the town of Malborghetto Valbruna is ceded to the Kingdom of Italy by the 1919 Treaty of Saint-Germain.