It was incorporated in 1765 by colonial governor Benning Wentworth and named for Sir Samuel Cornish, a distinguished admiral of the Royal Navy.

Since the late 19th century, Cornish has been a well-known summer resort for artists and writers.

Sculptor Augustus Saint-Gaudens began coming to Cornish in 1885, seeking a studio away from the summer heat of New York City.

Artist friends followed him, including painter and illustrator Maxfield Parrish, who designed and built his estate, the Oaks, in the area.

Cornish remains home to the longest two-span covered bridge in the world.

The Cornish–Windsor Covered Bridge spans the Connecticut River and was built in 1866 at an original cost of $9,000.

[5] The long ridge of Croydon Mountain follows the eastern boundary of town; the highest point in town is a knob on Croydon Mountain which reaches an elevation of 2,323 ft (708 m) above sea level.

[6] The eastern part of the town is a portion of the approximately 25,000-acre (100 km2) Blue Mountain Forest Association private game preserve, also known locally as Corbin Park, named after its founder, Austin Corbin.

Cornish is served by state routes 12A and 120, both of which connect Claremont to the south with Lebanon to the north.