South Stormont is a township in eastern Ontario, Canada, in the United Counties of Stormont, Dundas and Glengarry. It is located 53 kilometres (33 mi) southeast of Ottawa. South Stormont borders on, but does not include, the city of Cornwall.

The United Counties of Stormont, Dundas and Glengarry (SDG) is an upper-tier municipality in the Canadian province of Ontario that comprises three historical counties and excludes the City of Cornwall and the Mohawk Nation of Akwesasne. However, both Cornwall and Akwesasne form part of a larger census division named for the United Counties of Stormont, Dundas and Glengarry. The municipality's administrative office is located within Cornwall.