Alliston is a settlement in Simcoe County in the Canadian province of Ontario. It is part of the Town of New Tecumseth since the 1991 amalgamation of Alliston and nearby villages of Beeton, Tottenham, and the Township of Tecumseth. The primary downtown area is located along Highway 89, known as Victoria Street.

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. Honda of Canada Manufacturing operates a large auto manufacturing facility southeast of Alliston, currently consisting of three major factories.