Named in honour of Sir Charles Lennox, 4th Duke of Richmond and Lennox, who was Governor General of British North America 1818-1819, Richmond County was created in 1835.
Richmond County comprises that territory known as the Southern District which was established in 1824 at the time of the dividing of Cape Breton Island into three districts. The boundaries of the Southern District were defined at the time of its establishment. Those same boundaries were determined to be the boundaries of Richmond County by statute in 1847.