| C.H.G. Property Ltd | Real estate | 2014 |
| C.I. Retailers (N.I.) Limited | Wholesale & retail | 1987 |
| C.I.W.C. Ltd | Administrative & support | 2008 |
| C.J. Upton & Sons Limited | Wholesale & retail | 1973 |
| C.M.M. Kitchen Ltd | Hospitality | 2017 |
| C.R. Stores N.I. Ltd | Wholesale & retail | 2026 |
| C.S. Secretarial Services Ltd | Administrative & support | 2013 |
| C.S.Suppliers Limited | Wholesale & retail | 1974 |
| C.T. New Technologies Limited | Information & communication | 2020 |
| C.T. Properties Limited | Real estate | 1991 |
| C2 Energy Limited | Wholesale & retail | 2006 |
| C4A Health & Wellbeing Ltd | Health & social care | 2024 |
| C4VYP Ltd | Health & social care | 2020 |
| C51 Technologies Ltd | Professional & scientific | 2021 |
| C60 Limited | Professional & scientific | 2012 |
| CA Cbftd Ltd | Transport & logistics | 2017 |
| CAB Tours Belfast Ltd | Administrative & support | 2021 |
| Cabezo CS Ltd | Water & waste | 2021 |
| Cabin Hill 556 Management Company Limited | Households | 2007 |
| Cabin Hill House Management Company Limited | Households | 2003 |
| Cabin Hill Management Co. Ltd | Households | 2004 |
| Cabin Show Limited | Wholesale & retail | 2024 |
| Cabinzero NI Limited | Other services | 2025 |
| Cable Landfall Support Limited | Construction | 2020 |
| Cable Zero Limited | Wholesale & retail | 2023 |
| Cabletel Northern Ireland Limited | Administrative & support | 1995 |
| Cabo CAB Company Limited | Transport & logistics | 2023 |
| Cabragh Energy Ltd | Energy | 2025 |
| Cacada Limited | Construction | 2013 |
| Cacay Ltd | Health & social care | 2022 |
| Cache Phrase LP | | 2025 |
| Cachi Foods Limited | Extraterritorial | 2014 |
| Cacni Ltd | Health & social care | 2023 |
| Cactus Public Relations & Communications Ltd | Professional & scientific | 1999 |
| Cadenza Enterprises Limited | Information & communication | 2019 |
| Cadmax Engineering Ltd | Information & communication | 2019 |
| Cadmc Ltd | Information & communication | 2026 |
| Cadmono Ltd | Professional & scientific | 2024 |
| Cadogan (NO. 32) Property Limited | Households | 1992 |
| Cadogan Administration Services Ltd | Administrative & support | 2019 |
| Cadogan Futures LLP | | 2010 |
| Cadogan Healthcare Limited | Extraterritorial | 2026 |
| Cadolux Limited | Wholesale & retail | 2019 |
| Cadshare Technology Limited | Information & communication | 2014 |
| Caelina Ltd | Information & communication | 2025 |
| Caezu Mora Ltd | Wholesale & retail | 2026 |
| CAF Rail UK Limited | Manufacturing | 2004 |
| Cafe Cubano Limited | Hospitality | 2019 |
| Cafe Glen Limited | Hospitality | 2024 |
| Cafe Mauds Ballyhackamore Ltd | Hospitality | 2014 |
| Cafe Mauds Limited | Hospitality | 2011 |
| Cafe Melrose Ltd | Hospitality | 2017 |
| Cafe North N.I. Ltd | Hospitality | 2026 |
| Cafe Nosh Limited | Hospitality | 2011 |
| Cafe Nosh Malone Ltd | Hospitality | 2025 |
| Cafe Parisien (Belfast) Limited | Hospitality | 2017 |
| CAFE368 Ltd | Hospitality | 2022 |
| Caff Catering Ltd | Hospitality | 2025 |
| Caffrey Brickworks Ltd | Construction | 2026 |
| Cagey Productions Ltd | Professional & scientific | 2022 |
| Cahill Medical Services Ltd | Professional & scientific | 2020 |
| Cahir Linn Management Company Limited | Households | 2002 |
| Cahoon Consultancy Ltd | Information & communication | 2023 |
| Cahoots NI Ltd | Arts & recreation | 2001 |
| Caife Cineálta CIC | Hospitality | 2025 |
| Caimingji Ltd | Wholesale & retail | 2024 |
| Caindickson Ltd | Construction | 2023 |
| Cairde Events Ltd | Hospitality | 2026 |
| Cairde NA Cille C.I.C. | Administrative & support | 2023 |
| Cairn Acre Properties Limited | Construction | 2025 |
| Cairn Foods Limited | Hospitality | 2023 |
| Cairn Surveying & Engineering Ltd | Professional & scientific | 2026 |
| Cairnburn Grange Property Management Ltd | Real estate | 2008 |
| Cairnburn Holdings Limited | Financial services | 2018 |
| Cairnburn Investments Limited | Financial services | 1998 |
| Cairncastle House Limited | Financial services | 2024 |
| Cairncastle Mews Management Company Limited | Households | 2006 |
| Cairndore Management Limited | Real estate | 2018 |
| Cairnmore Developments Limited | Real estate | 2006 |
| Cairnshill Management Services Company Ltd | Extraterritorial | 2017 |
| Cairnshill Road Developments Limited | Extraterritorial | 1985 |
| Cairnwood Holdings Limited | Wholesale & retail | 2024 |
| Cairnwood Limited | Wholesale & retail | 2024 |
| Caiseal Court Management Co Ltd | Extraterritorial | 2009 |
| Caisleán Property Ltd | Real estate | 2025 |
| Caithness Architects Ltd | Professional & scientific | 2018 |
| Caitlin Ginley Hair Ltd | Other services | 2022 |
| Caitlin Ginley Salons Ltd | Other services | 2024 |
| Caitlin Ginley Training Academy Ltd | Other services | 2022 |
| Caitlin's Hairdressers Ltd | Other services | 2016 |
| CAK Audio Ltd | Information & communication | 2023 |
| CAL (N.I.) Ltd | Hospitality | 2019 |
| CAL Building Services Limited | Construction | 2017 |
| CAL Inns Ltd | Hospitality | 2024 |
| Cala Consulting Limited | Professional & scientific | 2022 |
| Caladrius Capital Ltd | Information & communication | 2018 |
| Calara Ltd | Professional & scientific | 2024 |
| Calcaric Limited | Wholesale & retail | 2025 |
| Calcatech Limited | Administrative & support | 2023 |
| Calcom Ventures Ltd | Wholesale & retail | 2024 |