The community of Cornwall traces its history to European settlement in the 18th century and was a predominantly farming community until the construction of Route 1, the Trans-Canada Highway, during the early 1960s. Several subdivisions were created near the intersection of the new highway with the Meadowbank Road, along with a small commercial strip.
The present town was incorporated by the provincial government in 1995 through municipal amalgamation which saw the following unincorporated rural communities merged:
The amalgamation did not see any controversies. It was claimed that the name of the community of Cornwall would survive while the others were dissolved. Residents of North River and other communities being subsumed had called for a new community name, as what occurred in the case of Stratford (also amalgamated at the same time).