South Ayrshire is one of thirty-two council areas of Scotland, covering the southern part of Ayrshire. It borders onto Dumfries and Galloway, East Ayrshire and North Ayrshire. South Ayrshire had an estimated population in 2021 of 112,450, making it the 19th–largest subdivision in Scotland by population. With an area of 472 sq mi, South Ayrshire ranks as the 15th largest subdivision in Scotland.

Ayrshire is a historic county and registration county, in south-west Scotland, located on the shores of the Firth of Clyde. The lieutenancy area of Ayrshire and Arran covers the entirety of the historic county as well as the island of Arran, formerly part of the historic county of Buteshire. Its principal towns include Ayr, Kilmarnock and Irvine and it borders the counties of Renfrewshire and Lanarkshire to the north-east, Dumfriesshire to the south-east, and Kirkcudbrightshire and Wigtownshire to the south. Like many other counties of Scotland, it currently has no administrative function, instead being sub-divided into the council areas of East Ayrshire, North Ayrshire and South Ayrshire. It has a population of approximately 366,800.