| Carrick Contracts Limited | Construction | 2018 |
| Carrick Formwork Limited | Construction | 2018 |
| Carrick House Holdings Limited | Real estate | 2025 |
| Carrick Plant Hire Ltd | Manufacturing | 1998 |
| Carrickasticken Contracts Ltd | Construction | 2024 |
| Carrickateel Management Company Limited | Households | 2007 |
| Carrickbracken Close Management Company Ltd | Households | 2016 |
| Carrickcloughan Farming Ltd | Agriculture & fishing | 2013 |
| Carrickcrua Limited | Mining & quarrying | 2025 |
| Carrickdale Enterprises Limited | Hospitality | 2010 |
| Carrickmacstay Developments Ltd | Construction | 2016 |
| Carrickmacstay Farms Ltd | Agriculture & fishing | 2021 |
| Carrickmacstay Hire Limited | Administrative & support | 2019 |
| Carrickmacstay Holdings Limited | Professional & scientific | 2019 |
| Carrickro Osteo Ltd | Health & social care | 2026 |
| Carrickroe Services Ltd | Construction | 2017 |
| Carrickshane Management Co. Ltd | Extraterritorial | 2008 |
| Carrickvale Manor Management Limited | Households | 2006 |
| Carrickview Developments Ltd | Real estate | 2026 |
| Carriff Properties Limited | Real estate | 2024 |
| Carrigdhoun Limited | Construction | 2018 |
| Carrive Close Management Ltd | Households | 2023 |
| Carrive Construction Consultants Ltd | Construction | 2017 |
| Carrive Developments Ltd | Real estate | 2023 |
| Carrivebane Ltd | Professional & scientific | 2010 |
| Carrogsowen Management Co Ltd | Households | 2015 |
| Carros Group Ltd | Construction | 2023 |
| Carrow Contracts Ltd | Construction | 2021 |
| Carryan Garden Room Limited | Hospitality | 2023 |
| Cars Direct Newry Ltd | Wholesale & retail | 2018 |
| Carton DIE (NI) Limited | Manufacturing | 2003 |
| Carton DIE Limited | | 2001 |
| Carval Limited | Wholesale & retail | 2024 |
| Carvill Engineering Consultants Ltd | Professional & scientific | 2026 |
| Carville Consultancy Ltd. | Professional & scientific | 2012 |
| Casa Loom Ltd | Manufacturing | 2022 |
| Casa Playa Investments Ltd | Real estate | 2022 |
| Casey Agri Plant and Machinery Sales Ltd | Wholesale & retail | 2025 |
| Casey Developments Ltd | Construction | 2017 |
| Casey Filling Station Ltd | Wholesale & retail | 2013 |
| Casey Supermarket Limited | Wholesale & retail | 2014 |
| Cashel Engineering Limited | Professional & scientific | 2012 |
| Cashel Property Ltd | Real estate | 2021 |
| Cashen Contracting Limited | Construction | 2023 |
| Casl Contracts Ltd | Construction | 2024 |
| Cassywater Outdoors Ltd | Agriculture & fishing | 2020 |
| Castaway Spa and Beauty Ltd | Other services | 2018 |
| Castle Enigan Farms Limited | Financial services | 2025 |
| Castle Feeds Limited | Wholesale & retail | 2023 |
| Castle Gate Homes Limited | Construction | 2003 |
| Castle Joinery & Fitout Limited | Construction | 2019 |
| Castle Mills Dromore Limited | Households | 2006 |
| Castle Online Media Limited | Information & communication | 2024 |
| Castle Park Properties Limited | Construction | 2015 |
| Castle View Inns Limited | Hospitality | 2013 |
| Castleblayney Container Storage Solutions Ltd | Transport & logistics | 2024 |
| Castledara Developments Ltd | Construction | 1999 |
| Castlefort Group Ltd | Water & waste | 2009 |
| Castlefort Stonemasonry Ltd | Construction | 2009 |
| Castlelough Ltd | Professional & scientific | 2015 |
| Castleview Outdoor Living Ltd | Wholesale & retail | 2021 |
| Cathal Mcmahon Plumbing & Heating Ltd | Construction | 2021 |
| Cathal Mulholland Electrical Ltd | Construction | 2021 |
| Catherine Allison & Co Limited | Administrative & support | 2023 |
| Catholic Working Mens Club Company Limited | Financial services | 1886 |
| Causeway Biochar Limited | Other services | 2021 |
| Causeway Coast Marathon Ltd | Arts & recreation | 2017 |
| Causeway Energy Limited | Other services | 2019 |
| Causeway Manor Management Ltd | Households | 2015 |
| Causeway Renewable Fuels Limited | Other services | 2023 |
| Causeway Renewables Limited | Other services | 2019 |
| Cavanagh Developments Ltd | Real estate | 2025 |
| Cavanhill Limited | Manufacturing | 2016 |
| Caverò Ltd | Information & communication | 2021 |
| CB Construction Ireland Ltd | Construction | 2020 |
| CBN Health Ltd | Wholesale & retail | 2022 |
| Cbnrg Limited | Professional & scientific | 2019 |
| Cbnt Construction Ltd | Construction | 2018 |
| CBW Property Limited | Real estate | 2026 |
| CC Graphics Limited | Professional & scientific | 2023 |
| Ccas Property Ltd | Real estate | 2013 |
| CCL Services (N.I.) Limited | Construction | 2002 |
| Ccnsg Ltd | Wholesale & retail | 2021 |
| CCR Distribution Limited | Transport & logistics | 2012 |
| Ccrc Morris Family Limited | Health & social care | 2025 |
| CD Architects Ltd | Professional & scientific | 2006 |
| CD Environmental Management Limited | Professional & scientific | 2014 |
| Cddw (NI) Limited | Administrative & support | 2020 |
| CDM Ireland Limited | Construction | 2020 |
| CE Prestige Group Ltd | Wholesale & retail | 2026 |
| Cedar Wood Management Company Ltd | Households | 2008 |
| Ceillinron Limited | Health & social care | 2013 |
| Celb Limited | Construction | 2020 |
| Celtic Lady Productions Limited | Arts & recreation | 2017 |
| Celtix BIO Labs Ltd | Professional & scientific | 2026 |
| Cemac Group Limited | Information & communication | 2017 |
| CEN Electrical Ltd | Construction | 2020 |
| Cenec Holdings Ltd | Construction | 2022 |
| Cenec Properties Ltd | Real estate | 2019 |
| Cenec Trading Limited | Construction | 2012 |