The Grenada Boys' Secondary School, initially known as St. George's Grammar School, opened on 2 February 1885 with ten male students at Mrs. Grey's premises on Hospital Street in St. George's.

In May 1946 the school was relocated to Tanteen to wooden barracks, which previously housed the Windward Island battalion for World War II.

The first phase of the new school was constructed from 2006 to 2008 by the government of Grenada, and funded by the World Bank.

The GBSS has been mainly a boys’ school but girls have also attended, especially for the sixth form (A-level) years.

Girls were admitted into Form I from 1982 (during the reign of the People's Revolutionary Government) until 1987, but were phased out by 1991.