Wild Horse Plains is a locality in South Australia located on the eastern coastline of Gulf St Vincent about 69 kilometres (43 mi) north-northwest of the Adelaide city centre. Its name is attributed to Thomas Day who found wild horses grazing within the locality circa 1870. Its boundaries were created in June 1997 and include the town of Wild Horse Plains, established in 1881 and located on Port Wakefield Road, and the “ceased Government Town of Lorne”. Port Lorne Road, which marks most of the northern boundary of Wild Horse Plains, refers to the same former town.
Wild Horse Plains is located within the federal Division of Wakefield, the state electoral district of Goyder and the local government area of the Adelaide Plains Council.