Alliston, Ontario is an Ontario community just about 90 kilometres NNW from Toronto, and about 40 km SW of Barrie, about 18 km W of Cookstown, about 10 km N of Tottenham, about 40 km NE of Orangeville and about 28 km E of Shelburne. It is part of the Town of New Tecumseth which is part of Simcoe County. (The 1991 amalgamation of Alliston, nearby villages Beeton and Tottenham, and the Township of Tecumseth, created one legal municipality, the Town of New Tecumseth. Municipal offices for the Town are located in Alliston.) The heart of the community is divided by Highway 89. It was founded in 1847 by English immigrant William Fletcher.
Alliston is located where the corners of four of the original townships of southern Simcoe County (Adjala, Tosorontio, Essa, and Tecumseth) meet.
Earl Rowe Provincial Park is located three kilometers west of Alliston, in the amalgamated Township of Adjala-Tosorontio. It is one of the largest provincial parks in Southern Ontario.
The town grew as a commercial centre for the area farmers and was best known as a potato-growing area. It is still a major industry in the town and is celebrated by the annual Alliston Potato Festival.