Connecticut's first governor, John Winthrop Jr., owned part of the farm in 1648. Over the years the land passed through various hands, including the Chester family in the 18th century, whose headstones are still on the property. When Caleb Haley owned and farmed the land in the late 19th to 20th centuries, he had a very unique hobby which can be seen throughout the park - the building of stone walls. Boulders found on the property were extracted and placed by an ox drawn stone-puller. The walls separated a number of pastures. Some remains of the farm's buildings are still visible near the entrance of the park.
In 1963, efforts to protect the farm from being sold to developers began. The State of Connecticut agreed to match funds raised for the purchase of the farm. The Groton Open Space Association with the help of The CT Forest & Park Association led a successful fund raising effort that led to the purchase of the property. In July of 1970, Life Magazine featured an article on Haley Farm titled "Battles Won". Haley Farm became an official Connecticut State Park in July of 1970. Nearby Bluff Point State Park and Coastal Reserve was protected from great development pressures and was saved in 1975. It can be reached from Haley Farm via a bridge over the railroad tracks. The two parks, combined, offer over 1000 acres of land and are permanently protected as open space for public enjoyment.