Charlemont High School was “conceptualized” by the late John Bernard “Jack” Stephenson, a former Member of Parliament for North St Catherine. The notion came about as a result of concerns expressed by parents in the area whose children had to attend schools outside the area, as far as Kingston and Claremont in St Ann. The land was bought from the late Custos McGrath. The funds for the building and infrastructure came from businesses and service clubs in North St Catherine including Alcan Jamaica Limited, the Lions Club, the United States and the Jamaica Citrus Growers Association. The St Catherine Garden Club landscaped the school grounds.
On September 1, 1978 , the first batch consisting of 240 students (120 boys and 120 girls ) was admitted. The staff complement was 12 teachers, 5 administrative workers, 10 ancillary workers and principal Mr.Ruel Forsythe.
The institution has changed over its 30 years of existence. Today they have 78 teachers and 1,437 students. In 1981 and again in 1998, major expansions occurred; thus facilitating the opportunity to provide quality education of its ever-growing intake of students. Their first batch of 42 sixth formers came on board on October 5, 1998. Member of Parliament, Hon. Robert Pickersgill was on hand to witness its commissioning.