The electorate of Mordialloc is located on Boonwurrung land. The name Mordialloc is said to be a combination of a couple of Indigenous words which could be interpreted as ‘flat water’, ‘swampy water’ or perhaps ‘near the little sea.’ The Mordialloc district takes in the Mordialloc Creek along with the Carrum Carrum Swamp, which were invaluable resources for the Bunurong people, who are the traditional owners of the land, delivering a consistent source of food across the plains.

It is a metropolitan electorate located approximately 18 kilometres south-east of Melbourne, with an area of 38 square kilometres. It encompasses the suburbs of Aspendale, Aspendale Gardens, Chelsea, Chelsea Heights, Edithvale, Moorabbin Airport, Mordialloc and Parkdale; along with parts of Bangholme, Cheltenham and Mentone.

The electorate includes both suburban areas and established and developing industrial estates.

The most distinguishing features of the Mordialloc electorate are its long coastal strip, the RAMSAR listed Edithvale-Seaford Wetlands Environmental Area, the Mordialloc Creek and the Moorabbin Airport.