| Carmel Mcguigan | Wholesale & retail | 2001 |
| Carn Industrial Services Ltd | Construction | 2025 |
| Carnamoney Properties Ltd | Real estate | 2017 |
| Carswood Limited | Construction | 2005 |
| Casino Royele Magherafelt Ltd | Arts & recreation | 2021 |
| Casmat UK Ltd | Wholesale & retail | 2016 |
| Castlelodge Homes Ltd | Construction | 2022 |
| Castlewood Kitchens (NI) Ltd | Manufacturing | 2013 |
| Cathcarts Kitchen Ltd | Manufacturing | 2023 |
| Cathcarts Toome Ltd | Wholesale & retail | 2023 |
| Cavanreagh Properties Ltd | Real estate | 2024 |
| CBC Events Ltd | Manufacturing | 2020 |
| CBS Construction Management Ltd | Construction | 2025 |
| CCR Retailing Ltd. | Wholesale & retail | 2015 |
| Cdmsport Ltd | Manufacturing | 2023 |
| Ceasefire Services Limited | Construction | 2018 |
| Celestina 1 Limited | Construction | 2020 |
| CEM Automation Ltd | Manufacturing | 2025 |
| Century Data Ltd | Construction | 2025 |
| CFA Energy Ltd | Administrative & support | 2024 |
| CFM Group Holdings Ltd | Financial services | 2025 |
| CH Contracts Ltd | Energy | 2018 |
| Ch-Cha Ltd | Wholesale & retail | 2026 |
| Chancery House Investments Limited | Real estate | 2016 |
| Charg-R Ltd | Manufacturing | 2022 |
| Charge to Go Ltd | Construction | 2022 |
| Chat&Chew Ltd | Hospitality | 2020 |
| Chemxpert NI Limited | Wholesale & retail | 2026 |
| Chesney Chanters & Reeds Ltd | Manufacturing | 2003 |
| Chestnut Heights Company Limited | Real estate | 2022 |
| Childwood Play Limited | Wholesale & retail | 2023 |
| Chopsticks Zheng Ltd | Hospitality | 2021 |
| CHP Trillium Holdings Ltd | Financial services | 2026 |
| Chris Copeland Photography Ltd | Professional & scientific | 2025 |
| Church View (IRL) Limited | Wholesale & retail | 2025 |
| Ciara Ltd | Wholesale & retail | 2020 |
| Circular Group Ltd | Manufacturing | 2020 |
| CJ Electrics Ltd | Construction | 2025 |
| Cjdbb Ltd | Wholesale & retail | 2023 |
| CJF Construction Ltd | Construction | 2025 |
| CJM Engineering Ltd | Professional & scientific | 2006 |
| CJW Property Services Limited | Real estate | 2016 |
| Clanrye Developments Limited | Real estate | 2004 |
| Clare Devlin Education Consultancy Ltd | Education | 2026 |
| Clarke Eco Wall Ltd | Construction | 2014 |
| Clarkes Court Ltd | Professional & scientific | 2001 |
| Clear Cloud Consulting Limited | Information & communication | 2020 |
| Clearview Property Management Limited | Construction | 2021 |
| Cleary Logistics Ltd | Transport & logistics | 2024 |
| Clerkin Technology Ltd | Information & communication | 2024 |
| Clinsupply Consulting Limited | Professional & scientific | 2025 |
| Cloane Developments Limited | Construction | 2014 |
| Cloane Farming Limited | Agriculture & fishing | 2019 |
| Cloane Properties Limited | Real estate | 2012 |
| Clonmore Capital Limited | Professional & scientific | 2011 |
| Clonoe Padel Ltd | Arts & recreation | 2026 |
| Close Contracts Ltd | Construction | 2025 |
| Cloverpark Trading Limited | Agriculture & fishing | 2010 |
| Clubsync Ltd | Arts & recreation | 2025 |
| CM Freight Limited | Transport & logistics | 2024 |
| CM Sons Home Improvements Limited | Construction | 2025 |
| CMD Electrical Limited | Construction | 2011 |
| CMK Electrics Ltd | Construction | 2017 |
| Cnnctd Ltd | Wholesale & retail | 2023 |
| Coco Craft Pizza LLP | | 2020 |
| Cogry Mill Holdings Limited | Administrative & support | 2005 |
| Colfab Ltd | Professional & scientific | 2021 |
| Colin James Clarke Limited | Extraterritorial | 2022 |
| Collins Vets Limited | Professional & scientific | 2021 |
| Colloide Engineering Systems Ltd | Water & waste | 2002 |
| Colloide Site Services Ltd | Water & waste | 2017 |
| COM Foods Ltd | Hospitality | 2020 |
| Combined Building Services UK & Ireland Ltd | Construction | 2021 |
| Commercial and Plant Spraying Ltd | Agriculture & fishing | 2018 |
| Commercial Executive Cleaning Limited | Administrative & support | 2019 |
| Compass Risk Ltd | Financial services | 2024 |
| Connected Appliances Limited | Wholesale & retail | 2016 |
| Construction Plant Repairs Limited | Manufacturing | 2014 |
| Consul Services (NI) Limited | Professional & scientific | 1997 |
| Consul Services FM Limited | Professional & scientific | 2004 |
| Consul Services Holdings Limited | Professional & scientific | 2004 |
| Convery Environmental Consultancy Limited | Professional & scientific | 2022 |
| Conway Energy Limited | Energy | 2015 |
| Conway Holdings Limited | Energy | 2015 |
| Conway Holdings NO. 1 Ltd | Financial services | 2024 |
| Conway Holdings NO. 2 Ltd | Financial services | 2024 |
| Conway Holdings NO. 3 Ltd | Financial services | 2025 |
| Conway Mechanical Services Limited | Construction | 2016 |
| Coolcalm Holdings Limited | Financial services | 2025 |
| Corban Properties Ltd | Extraterritorial | 2004 |
| Corramore Construction Ltd | Construction | 1999 |
| Corramore Group Limited | Financial services | 2023 |
| Corramore Holdings Limited | Professional & scientific | 2014 |
| Corry Dental Care | Health & social care | 1999 |
| Cosida Holdings Ltd | Financial services | 2022 |
| CPJ Holdings Limited | Financial services | 2020 |
| Cran BÁN Holdings Ltd | Real estate | 2025 |
| CRD Retail Limited | Wholesale & retail | 2015 |
| Creagh Precision Joinery Limited | Manufacturing | 2014 |
| Croga Tours Ltd | Administrative & support | 2022 |