The Mallee covers the most northwesterly part of Victoria, bounded by the South Australian and New South Wales borders. Definitions of the south-eastern boundary vary, however, all are based on the historic Victorian distribution of mallee eucalypts. These trees dominate the surviving vegetation through most of Mallee, (except for swamps and areas along waterways, and very rare stands of casuarina). Its biggest settlements are Mildura and Swan Hill.

At the 2011 census, the four local government areas (LGAs) that are usually thought to define the district had a combined population of 88,178. The area of these same four LGAs is 40,183 square kilometres (15,515 sq mi).

There is an adjacent area also once covered with mallee scrub called "the Mallee" in South Australia, which is alternatively called the Murray Mallee.