Corse-du-Sud is an administrative department of France, consisting of the southern part of the island of Corsica. The corresponding departmental territorial collectivity merged with that of Haute-Corse on 1 January 2018, forming the single territorial collectivity of Corsica, with territorial elections coinciding with the dissolution of the separate council. Although its administrative powers were ceded to the new territorial collectivity, it continues to remain an administrative department in its own right. In 2019, it had a population of 158,507.

In the administrative divisions of France, the department is one of the three levels of government under the national level, between the administrative regions and the communes. Ninety-six departments are in metropolitan France, with an additional five constituting overseas departments, which are also classified as overseas regions. Departments are further subdivided into 333 arrondissements and 2,054 cantons. These last two levels of government have no political autonomy, instead serving as the administrative basis for the local organisation of police, fire departments as well as, in certain cases, elections.