List of historic places in Southwestern Ontario

This is a list of historic places in Southwestern Ontario, containing heritage sites listed on the Canadian Register of Historic Places (CRHP), all of which are designated as historic places either locally, provincially, territorially, nationally, or by more than one level of government.

The following subregions have separate listings:
 * County of Brant
 * Essex County
 * Middlesex County
 * Perth County
 * Regional Municipality of Waterloo
 * Wellington County