| Cummings Global Ltd | Professional & scientific | 2011 |
| Cumulus Neuroscience Limited | Information & communication | 2015 |
| Cunning Coach Hire Ltd | Transport & logistics | 2026 |
| Cunning Funeral Directors Ltd | Other services | 2026 |
| Cunningham Cars Ltd | Wholesale & retail | 2023 |
| Cunningham House LLP | | 2008 |
| CUP (Ireland) Limited | Real estate | 2012 |
| Cupimatch Limited | Wholesale & retail | 2025 |
| Cura Health Limited | Health & social care | 2023 |
| Cura Salt Room Ltd | Other services | 2026 |
| Curated Frame Art Gallery Ltd | Wholesale & retail | 2025 |
| Curated Kitchen Limited | Hospitality | 2017 |
| Curio Ltd | Wholesale & retail | 1999 |
| Curiosity Corporation Limited | Information & communication | 2022 |
| Curragh Road Wind Limited | Energy | 2016 |
| Curran Bowles Family Law Ltd | Professional & scientific | 2021 |
| Curran Connolly & Co. Ltd. | Financial services | 2012 |
| Curran Court Hotel 2017 Limited | Hospitality | 2015 |
| Curran Media Ltd | Professional & scientific | 2021 |
| Curran Property Investments Limited | Real estate | 2025 |
| Curran Retail Ltd | Wholesale & retail | 2020 |
| Currant Management LP | | 2022 |
| Current Zhen Limited | Wholesale & retail | 2024 |
| Currently Beautiful Ltd | Other services | 2019 |
| Curry Cottage 2024 NI Ltd | Hospitality | 2024 |
| Curtis Psychology Services Limited | Health & social care | 2019 |
| Curvy Chic Bridal Limited | Wholesale & retail | 2018 |
| Curvy Chic Online Limited | Wholesale & retail | 2018 |
| Curzon Management Company (NI) Limited | Real estate | 2007 |
| Cuscab Ltd | Manufacturing | 2020 |
| Cushon MT NI Limited | Administrative & support | 2001 |
| Cusick Orthopaedics Ltd | Health & social care | 2020 |
| Cusk Properties Limited | Extraterritorial | 2016 |
| Cuskeran Investments NO1 Limited | Financial services | 2024 |
| Cuskeran Investments NO2 Limited | Real estate | 2024 |
| Custom Blinds and Shutters Cleaning Ltd | Manufacturing | 2021 |
| Custom Blinds and Shutters Ltd | Manufacturing | 2020 |
| Custom Connect Ltd | Information & communication | 2013 |
| Custom Construction & Joinery Ltd | Construction | 2021 |
| Custom House Belfast Limited | Real estate | 2026 |
| Custom House Cafe Ltd | Hospitality | 2018 |
| Custom House Square Apartments Management Company Limited | Households | 2007 |
| Custom Vehicle Solutions Limited | Wholesale & retail | 2013 |
| Cutn Crew Limited | Other services | 2016 |
| Cutter S Lane Management Company Limited | Households | 2005 |
| Cutting Edge Curtains Ltd | Manufacturing | 2013 |
| Cutting Industries Ltd | Manufacturing | 1996 |
| Cuttyshane Limited | Construction | 2020 |
| CV Holywood Ltd | Construction | 2017 |
| CV6 Therapeutics (NI) Limited | Health & social care | 2014 |
| CVG (D.C.) Limited | Extraterritorial | 2013 |
| CVM Property Ltd | Real estate | 2025 |
| Cvmt Limited | Other services | 2016 |
| Cvwqhpwbcx Limited | Wholesale & retail | 2023 |
| CW Travel UK, Ltd. | | 1996 |
| CWN Hair Pieces Ltd | Other services | 2023 |
| CWS Properties Limited | Real estate | 2013 |
| CXW Great Open Limited | Wholesale & retail | 2025 |
| Cyan Forward Ltd | Wholesale & retail | 2023 |
| Cyber Guarded (N.I.) Ltd | Information & communication | 2016 |
| Cyber Security (N.I.) Ltd | Information & communication | 2017 |
| Cyberavity Limited | Wholesale & retail | 2026 |
| Cyberaxis Ltd | Information & communication | 2026 |
| Cyberexpobelfast Limited | Extraterritorial | 2025 |
| Cyberpark Group Ltd | Extraterritorial | 2017 |
| Cyberpark NI Ltd | Information & communication | 2017 |
| Cybersafenow Ltd | Information & communication | 2019 |
| Cybersource NI Limited | Information & communication | 2008 |
| Cyberspark Academy Ltd | Administrative & support | 2022 |
| Cyberspark Group Ltd | Information & communication | 2017 |
| Cyberteq Ltd | Information & communication | 2025 |
| Cybit North Limited | Information & communication | 2014 |
| Cybrex Ltd | Information & communication | 2023 |
| Cyclami Limited | Wholesale & retail | 2023 |
| Cygilant UK Limited | Information & communication | 2019 |
| Cylin OIL & Allied Services International Ltd | Wholesale & retail | 2023 |
| Cymsoft Limited | Information & communication | 2018 |
| Cynalytica International Ltd | Information & communication | 2020 |
| Cyncro Limited | Professional & scientific | 2021 |
| Cynosure Beauty Place Ltd | Other services | 2024 |
| Cynosure Properties Limited | Households | 2026 |
| Cyplena Limited | Information & communication | 2024 |
| Cyprus Autos Ltd | Wholesale & retail | 2025 |
| Cyprus Avenue Films Limited | Information & communication | 2010 |
| Cyprus Avenue Limited | Hospitality | 2020 |
| Cyprus Consulting Ltd | Health & social care | 2023 |
| Cyprus Foods NI Ltd | Hospitality | 2025 |
| Cyprus Mews Ltd | Real estate | 1998 |
| Cyril Johnston & Co., Limited | Wholesale & retail | 1954 |
| Cyril Johnston Hire Limited | Administrative & support | 1977 |
| Cyril Johnston Trading Limited | Real estate | 2018 |
| Cytrus HK Limited | Wholesale & retail | 2025 |
| D & a Property Developments Limited | Construction | 2016 |
| D & D Holywood Limited | Hospitality | 2017 |
| D & F Investments Limited | Other services | 2011 |
| D & G Global Financial Planning Ltd | Financial services | 2024 |
| D & H Motors Limited | Wholesale & retail | 2010 |
| D & M Casement Limited | Financial services | 2019 |
| D & R Graham (Developments) Limited | Administrative & support | 1990 |
| D a Brickwork Contractors Ltd | Construction | 2016 |