The history of Berwick Academy dates back to 1791, when the citizens of Berwick, York, Kittery, Rollinsford, Portsmouth, and Wells raised 500 pounds to educate the local youth.
Incorporated by the Massachusetts Legislature and with a charter signed by Governor John Hancock for the purpose of "promoting true piety and virtue and useful knowledge among the rising generation," Berwick Academy was established to teach languages, liberal arts, and sciences.
When Maine became a state in 1820, Berwick Academy was the equivalent of a comprehensive high school and, until the 1950s, the town of South Berwick contracted with the School to educate local students. However, by 1955, the Board of Trustees reverted to a completely private status with an exclusive college preparatory program in accordance with the intent of the School's founders.
Berwick became a boarding school for boys, with a day department for girls, and continued to expand its facility by acquiring land for playing fields and tennis courts, as well as nine homes for dormitories and faculty housing. A new gymnasium and The Commons, housing a dining hall and science laboratories, were completed by the mid-1960s. Berwick experienced tremendous changes during the 1970s–adding the Middle School in 1971 and discontinuing the boarding program in 1976. With the addition of the Lower School in 1977, the transformation to a true country day school was complete.
Berwick continued to expand its facility with the dedications of the Whipple Arts Center in 1985, the Kendall Lower School in 1988, the Clement Middle School in 1994, the Athletic Center in 1997, the Jeppesen Science Center in 1999, the Jackson Library in 2002, the Walsh Wellness Center at Oakes House in 2015, and the Inspiration Commons in the Jackson Library in 2016.