The school was founded in 1908 as the second high school to be constructed in the city, and is now the oldest remaining secondary school. The first classes were held in the Admiral Seymour Elementary School building in September 1908. The school moved to the then partially completed Britannia building in 1910. The school colours of red, green, and white and the school motto "Per Vias Rectas" were adopted at this time. During the 1966-67 school year, a new wing was constructed and now houses the school office. In 1974, Britannia Secondary became Britannia Elementary-Secondary School. Britannia celebrated its in 2008.