Horsham is a regional city in the Wimmera region of western Victoria, Australia. Located on a bend in the Wimmera River, Horsham is approximately 300 kilometres (190 mi) northwest of the state capital Melbourne. As of the 2021 census, Horsham had a population of 20,429. It is the most populous city in Wimmera, and the main administrative centre for the Rural City of Horsham local government area. It is the eleventh largest city in Victoria after Melbourne, Geelong, Ballarat, Bendigo, Wodonga, Mildura, Shepparton, Warrnambool, Traralgon, and Wangaratta.

The Victorian government's Wimmera Southern Mallee subregion is part of the Grampians region in western Victoria. It includes most of what is considered the Wimmera, and part of the southern Mallee region. The subregion is based on the social catchment of Horsham, its main settlement.