Southland District is a New Zealand territorial authority district that covers most of the southern end of the South Island as well as Stewart Island.

Southland District was formed through the 1989 local government reforms. Four local authorities were amalgamated at that time: Wallace County, Winton Borough, Stewart Island County and most of Southland County. John Casey, who was first elected onto Southland County Council in 1977, oversaw the amalgamation and was elected Southland District's first mayor in 1989.

Winton Wallacetown Ward was renamed Oreti Ward with effect from the Council election on 12 October 2019. The Ōreti River flows through this ward.

Southland District covers the majority of the land area of Southland Region, although the region also covers Gore District, Invercargill City and adjacent territorial waters. It has a land area of 29,574.53 square kilometres (11,419 sq mi), excluding inland waters such as Lake Te Anau, Lake Manapouri, and Lake Hauroko.

Southland District contains the islands south of Foveaux Strait:

The seat of the district council is Invercargill, which, however, is not part of Southland District, but a territorial authority in its own right.

Two of New Zealand's largest national parks are within the boundaries of Southland District: Fiordland National Park, and Rakiura National Park (which covers most of Stewart Island / Rakiura).

The Southland District has three towns with a population over 1,000. Together, they are home to 21.2% of the district's population.