Campbell College located in Belfast, Northern Ireland, and founded in 1894 comprises a preparatory school department (junior age) and a senior Northern Ireland Voluntary Grammar school, the latter meaning, in terms of provision of education, a government funded, selective school.

The school is one of a number of schools in the state funded grammar sector in Northern Ireland which can offer paid boarding places to some pupils, typically to be funded by the pupil, although most pupils are dayboys.

It is one of the eight schools of Northern Ireland represented on the Headmasters' and Headmistresses' Conference and is a member of the Independent Schools Council.

Campbell College is one of very few voluntary grammar schools in Northern Ireland entitled to be classified as a 'Voluntary B' grammar school, where most voluntary grammars within this state sector are 'Voluntary A'. Voluntary grammar schools, though state schools by educational funding, are each managed by independent educational charities on the privately owned grounds and infrastructure of those charities. The College's 'Voluntary B' designation enables this grammar school, which is state funded for education provision, to charge a degree of fees to pupils, separate completely to the education process, officially termed the "capital fee".

The capital fees charged to the grammar school pupils are purely for the upkeep of historic buildings and grounds and not for any part of the education. (Voluntary 'B' grammars receive much less state capital funding for physical upkeep than other voluntary grammars.) At Campbell College the schooling itself in the grammar school does not come under fee-paying terms. In common with all other Northern Ireland grammar schools of all types, the schooling itself is taxpayer funded per pupil through the government authority for those successful in admission within the school's own selection process.

The school occupies a 100-acre (40-hectare) estate in east Belfast, close to the Parliament Buildings at Stormont. All the school's facilities are located on this site, which also contains a small lake and forest named Netherleigh.

Campbell's junior school – formerly located on an adjacent site and called Cabin Hill – is now also located on the site. The school has the oldest Combined Cadet Force in Northern Ireland, with over 400 cadets. The school has an international reputation and attracts boarders from all over the world.

It was founded in 1894 with a bequest by Henry James Campbell, who made his fortune in the linen trade, and left money to found a school based on the values of a Liberal Protestant education. Initially the school was primarily a boarding school but it has, particularly since the 1970s, become primarily a day school; in 2009 it had 879 pupils, only about 85 (10%) of whom were boarders. As a selective independent school, it admits pupils based on academic selection. Until 2006 pupils began at the school at age 11, but since the closure of the school's separate preparatory school, Cabin Hill, the school has accepted pupils from age 4 into the newly built Junior School, and both boys and girls into the school's kindergarten located on the school's grounds. The Latin motto of the school is Ne Obliviscaris ("Do Not Forget").^{[citation needed]}