- Applewood Acres
- Apsley
- Apto
- Arbeatha Park
- Ardbeg
- Ardendale
- Ardmore Beach
- Ardoch
- Ardtrea
- Ariss
- Arkell
- Arklan
- Arlington Woods
- Armstrong
- Armstrong Mills
- Armstrong Station
- Armstrongs Corners
- Arnott
- Arran-Elderslie
- Arranvale
- Arthur
- Arthur's Corners
- Arva
- Ashby Mill
- Ashton
- Ashton Station
- Asselstine
- Assumption
- Astorville
- Astra