From 2002 to May 2018 each parliamentary constituency in Croydon was made up of exactly eight wards, all fully contained within it. Shortly after taking control in 2014 Croydon Labour requested a review of the local authority boundaries. This has resulted in each ward in the borough changing, and the size of wards become much more varied, each contraining one, two or three councillors. As a result, the wards can no longer fit neatly into the three parliamentary constituencies and a number now appear in two parliamentary constituences.
Croydon South covers the south-western part of the London Borough of Croydon.