The construction of Harrison Trimble High School began in September 1960 and was first occupied by classes in September 1961. At that time, the school had 37 teachers and 25 classes with an enrolment of 837 students. HTHS was unique in that it was the first one in the greater Moncton area to have bilingual high school grade in the same building with English students in academic and commercial classes. Today, HTHS has over 75 teachers with an enrolment of over 1,260 students.

The school is named in honour of Dr. H. H. Trimble, who was born and educated in Hampton, NB. He is a graduate of UNB and was a star athlete in football, basketball, and track. Dr. Trimble served in the First World War. He came to Moncton in 1922 and taught at the former Aberdeen High School. In addition, he served as Secretary of the School Board and Superintendent of the Moncton Schools.