| Carlin Contracts Ltd | Agriculture & fishing | 2021 |
| Carlingford Developments Limited | Real estate | 2015 |
| Carmichael Contracts Ltd | Construction | 2023 |
| Carmichaels (NI) Limited | Hospitality | 2004 |
| Carnadale Limited | Financial services | 2024 |
| Carnaglass Properties Limited | Real estate | 2013 |
| Carnalbanagh Holdings Limited | Financial services | 2024 |
| Carngore Limited | Information & communication | 1995 |
| Carngrove Properties Limited | Real estate | 2023 |
| Carnlea Tanning Limited | Other services | 2017 |
| Carnlough Community Development Group Ltd | Administrative & support | 1993 |
| Carnview Consumable Supplies Ltd | Wholesale & retail | 2023 |
| Carnwood Hall Developments Limited | Households | 2019 |
| Carnwood Management Company (N.I.) Limited | Households | 2016 |
| Carnwood Properties Limited | Construction | 2014 |
| Carousel Limited | Wholesale & retail | 2001 |
| Carrigeen Farms Limited | Agriculture & fishing | 1979 |
| Carson Black Limited | Information & communication | 2024 |
| Casadirect Ltd | Wholesale & retail | 2021 |
| Casdon Developments Limited | Construction | 1997 |
| Cashel Mills Limited | Information & communication | 2022 |
| Caspendevelopments Limited | Construction | 2014 |
| Castle Entertainment Centre Limited | Information & communication | 1990 |
| Castle Festivals Limited | Arts & recreation | 2024 |
| Castle Lodge Management Association Limited | Real estate | 2001 |
| Castle Timber Recycling Limited | Water & waste | 2015 |
| Castlehill Property Developments Ltd | Real estate | 2020 |
| Catacove Properties Limited | Real estate | 2002 |
| Caterfab Engineering Limited | Manufacturing | 2015 |
| Catherine Adams Financial Planning Limited | Financial services | 2014 |
| Cats EYE Lighting Limited | Information & communication | 2015 |
| Cats EYE Media Limited | Administrative & support | 2025 |
| Caulfield Catering Ltd | Hospitality | 2025 |
| Causeway Sales Limited | Wholesale & retail | 2016 |
| CB Pro Ltd | Extraterritorial | 2021 |
| CBW Trading Limited | Wholesale & retail | 2023 |
| Cdillon Professional Services Ltd | Professional & scientific | 2019 |
| Cdnr Property Ltd | Real estate | 2013 |
| CDX Coaching Ltd | Other services | 2025 |
| Cedar Fence Rentals Ltd | Real estate | 2025 |
| Celebration House | Other services | 2016 |
| Celtic Marketing Limited | Other services | 2021 |
| Cemc Global Ltd | Hospitality | 2022 |
| Cennick Ltd | Wholesale & retail | 2023 |
| Cequel Developments Ltd | Information & communication | 2007 |
| CF Eyecare Ltd | Health & social care | 2020 |
| Cfit Personal Training Ltd | Arts & recreation | 2022 |
| CFL (N.I.) Ltd | Arts & recreation | 2016 |
| Cget Limited | Professional & scientific | 2014 |
| Channel Wharf Wealth Management Limited | Financial services | 2017 |
| Charleton IT Ltd | Information & communication | 2023 |
| Cheema Sons Ballymena Ltd | Wholesale & retail | 2024 |
| Cherry Energy Limited | Energy | 2013 |
| Chester Cottages Management Limited | Households | 2004 |
| Chilltec Refrigeration Ltd | Manufacturing | 2004 |
| Chip on the Hill Ltd | Hospitality | 2025 |
| Chipmaster Limited | Wholesale & retail | 2020 |
| Chitterbugs Ltd | Education | 2023 |
| Chivaye Ltd | Wholesale & retail | 2024 |
| Church Court Rasharkin Management Company Limited | Administrative & support | 2013 |
| Church Street Holdings Ltd | Construction | 2022 |
| Ciga Healthcare (Holdings) Limited | Financial services | 2012 |
| Ciga Healthcare Limited | Wholesale & retail | 2005 |
| Ciga Holdings Limited | Financial services | 2025 |
| CJ Recreation Ltd | Arts & recreation | 2023 |
| CJA Home & Toys Ltd | Wholesale & retail | 2026 |
| CJC (N.I.) Ltd | Hospitality | 2016 |
| CJR Commerce Limited | Wholesale & retail | 2024 |
| CK Ecommerce Ltd | Wholesale & retail | 2025 |
| Ckni Ltd | Hospitality | 2011 |
| CKS Cable Jointing Ltd | Construction | 2015 |
| Clady Crispy Catch Ltd | Hospitality | 2025 |
| Clarann Haulage Limited | Transport & logistics | 2009 |
| Clarke Contracts (Plastering & Flooring) Ltd | Construction | 2010 |
| Clarke Facades Ltd | Construction | 2015 |
| Clarke Group (N.I.) Ltd | Construction | 2016 |
| Clarke Holdco Limited | Financial services | 2023 |
| Clarke Offsite Limited | Construction | 2011 |
| Clarke Prop Holdco Limited | Financial services | 2022 |
| Clarke Properties (N.I.) Ltd | Real estate | 2018 |
| Clarke Trade Holdco Limited | Financial services | 2022 |
| Clavelle Ltd | Information & communication | 2017 |
| Clear Fuel Ltd | Wholesale & retail | 2019 |
| Clear Trainings Ltd | Wholesale & retail | 2021 |
| Cleenish Properties Limited | Real estate | 2024 |
| Cleggan Estate Company Limited-The | Agriculture & fishing | 1996 |
| Clements Financial Solutions Ltd | Financial services | 2024 |
| Cliext Ltd | Information & communication | 2026 |
| Clodagh Rose Virtual Ltd | Other services | 2022 |
| Cloneytrace Ltd | Wholesale & retail | 2022 |
| Cloud Performance Ltd | Information & communication | 2021 |
| Cloughmills Community Action Team | Agriculture & fishing | 2011 |
| CM Cars N.I. Ltd | Wholesale & retail | 2016 |
| CM Construction Services (N.I.) Ltd | Construction | 2016 |
| CM Power Solutions Limited | Other services | 2016 |
| Cmac Anaes Limited | Health & social care | 2022 |
| CMC Plumbing Limited | Construction | 1996 |
| CMD Plumbing and Heating Limited | Construction | 2017 |
| CML Haulage Ltd | Transport & logistics | 2017 |
| CMM Trading Ltd | Wholesale & retail | 2022 |