Easton's roots reach back to 1762, when the Connecticut General Assembly established the parish of North Fairfield. In 1787, the legislature combined North Fairfield with the neighboring Norfield parish to form the town of Weston. Nearly six decades later, in 1845, North Fairfield split away from Weston to become its own town, taking the name Easton.

Long before European settlement, the land was home to the Aspetuck, one of five bands of the Pequonnock people, who lived in what is now Easton near the Hemlock Reservoir. Early English settlers cleared much of the forest for farming, and through the 18th and 19th centuries, Easton grew into a community of small farms, mills, and craftsmen, supplying goods to the American Revolution, the War of 1812, and the Civil War.

The Industrial Revolution changed everything. As factories replaced water-powered mills and railroads replaced wagons, many Easton farmers moved west in search of larger, more fertile land, while others found work in nearby Bridgeport. Late in the 19th century, the Bridgeport Hydraulic Company began acquiring Easton land for reservoirs to supply the growing city's water needs, permanently shaping the rural character the town is known for today.