| Southwest Middlesex | |
| Official Name: | Municipality of Southwest Middlesex |
| Settlement Type: | Municipality (lower-tier) |
| Flag Size: | 120x100px |
| Mapsize: | 200px |
| Pushpin Map: | CAN ON Middlesex#Canada Southern Ontario |
| Coordinates: | 42.75°N -123°W |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Type2: | County |
| Established Title: | Settled |
| Established Title2: | Formed |
| Established Date2: | January 1, 2001 |
| Leader Title: | Mayor |
| Leader Name: | Allan Mayhew |
| Leader Title1: | Federal riding |
| Leader Title2: | Prov. riding |
| Area Land Km2: | 427.88 |
| Population As Of: | 2016 |
| Population Footnotes: | [1] |
| Population Total: | 5723 |
| Population Density Km2: | 13.4 |
| Utc Offset: | -5 |
| Utc Offset Dst: | -4 |
| Postal Code: | N0L, N0M |
| Website: | www.southwestmiddlesex.ca |
Southwest Middlesex is a municipality in Middlesex County, Ontario, Canada.
The restructured municipality of Southwest Middlesex was incorporated on January 1, 2001. This amalgamation joined the Village of Glencoe and the Village of Wardsville with the Townships of Ekfrid and Mosa. Southwest Middlesex had a population of 5,723 in the Canada 2016 Census. Southwest Middlesex is located in the southwest corner of Middlesex County, about halfway between London and Chatham.
The township includes the communities of Appin, Ekfrid, Glencoe, Lewis Corners, Macksville, Mayfair, Newbury Station, North Appin Station, North Ekfrid, North Glencoe Station, Riverside, Strathburn, Tait’s Corners, Wardsville and Woodgreen. It surrounds, but does not include, the independent village of Newbury. The township administrative offices are located in Glencoe.
Wardsville was the site of the Battle of Longwoods during the War of 1812.
Canadian National Railway's Longwood Subdivision passes through Southwest Middlesex. A signpost for Appin is at mile 23 of the Longwood Sub.
In the 2021 Census of Population conducted by Statistics Canada, Southwest Middlesex had a population of living in of its total private dwellings, a change of from its 2016 population of . With a land area of 427.82km2, it had a population density of in 2021.[2]