Cornwall County may refer to:
- Cornwall County, Province of New York, United States
- Cornwall County, Jamaica
- the former name of Cornwall Land District, Tasmania, Australia
- Cornwall (), England, UK; a county, and former countdom
- United Counties of Stormont, Dundas and Glengarry, Ontario, Canada; sometimes called "County of Cornwall"
- Cornouaille (), Brittany, France; a former sovereign county, also spelled as "Cornwall"
See also