Essex is located in Middlesex County east of New Haven between Chester and Old Saybrook along US Highway 9 on the banks of the Connecticut River near Long Island Sound. Cockaponset State Forest and Wrights Pond are nearby.

The community was named after Essex, England. Once a shipbuilding center. Later, the manufacture of witch hazel and piano keys, which became two important industries.

Most of Essex was initially known as the Potapoug Quarter of the Saybrook Colony. In 1852, Essex became (although called Old Saybrook until 1854 when Essex became the official name).

Local attractions include: Hamburg Cove, Lower Pond, Upper Pond, Eightmile River, Nehantic State Forest, Uncas Pond, Rogers Lake, Lord Cove, Mill Pond, Bushy Hill Reservoir, Selden Neck State Park, and Gillette Castle State Park.