It is also one of nine constituencies in the South Scotland electoral region which elects seven additional members to the Scottish Parliament via a proportional electoral system known as the Additional Members System (abbreviated AMS) which allows for greater accuracy in representation for the region as a whole.

The other eight constituencies of the South Scotland region are: Carrick, Cumnock and Doon Valley; Clydesdale; Dumfriesshire; East Lothian; Ettrick, Roxburgh and Berwickshire; Galloway and West Dumfries; Kilmarnock and Irvine Valley and Midlothian South, Tweeddale and Lauderdale.

The remaining wards in South Ayrshire form part of the Carrick, Cumnock and Doon Valley .

The town of Ayr serves as the administrative centre of the South Ayrshire Council area and is the most populated section of the constituency.

Historically the Ayr seat has held a higher level of support for the Conservative Party in comparison to elsewhere in Scotland and the United Kingdom as a whole.

In spite of this, at the 1997 election, the Ayr seat returned one of the smallest pro-Labour swings in Great Britain at just over 5%.

At the 2017 UK general election, Conservative candidate Bill Grant gained the overlapping Westminster constituency of Ayr, Carrick and Cumnock from the SNP with a majority of 2,774 votes (6.0%), but the SNP regained it at the 2019 UK general election with a majority of over 2,000 votes.

In 2021, the SNP's Siobhian Brown gained the Ayr constituency from Scott with a narrow majority of 170 votes on a record high turnout of 68%.