The ward of St Mary's is one of five wards that make up the town of Andover. St Mary's covers 677 hectares in the north-eastern part of Test Valley and is located on the north-eastern edge of Andover.
The ward is diverse in nature, containing most of Andover town centre and Walworth Business Park together with areas of mixed residential. These include Pilgrims Way, River Way, Admirals Way and Vigo Road as well as the new community at Picket Twenty. It has one of the largest concentrations of jobs and the town centre means its housing density is relatively high.