Cape Breton County is one of eighteen counties in the Canadian province of Nova Scotia. It is located on Cape Breton Island. From 1879 to 1995, the area of the county excluded from towns and cities was incorporated as the Municipality of the County of Cape Breton to provide local government services. Since 1995 the only municipality in the county has been a single-tier municipality called Cape Breton Regional Municipality.

Taking its name from Cape Breton, the most easterly point of the island which was called after the Bretons of Brittany, the county has what is probably the oldest surviving European name to have been used to designate part of North America.