C
- Carrickfergus College, Carrickfergus, County Antrim
- Castlederg High School, Castlederg, County Tyrone
- C.B.S. Glen Road, Belfast
- City of Armagh High School, Armagh
- Clounagh Junior High School, Portadown, County Armagh
- Coláiste Feirste, Irish-medium school, Belfast, County Antrim
- Coláiste Chaitríona, Irish-medium school, County Armagh
- Coláiste Phádraig, Irish-medium school, County Londonderry
- Coleraine College, Coleraine, County Londonderry
- Cookstown High School, Cookstown, County Tyrone
- Corpus Christi College, Belfast
- Craigavon Senior High School, Portadown, County Armagh
- Cross and Passion College, Ballycastle, County Antrim
- Crumlin High School, Crumlin, County Antrim
- Cullybackey High School, Cullybackey, County Antrim
Read more about this topic: List Of Secondary Schools In Northern Ireland