| Crossmaglen Development Management Limited | Households | 2008 |
| Crossmaglen Sports and Recreation C.I.C. | Education | 2023 |
| Crossmaglen Vets Ltd | Professional & scientific | 2024 |
| Crowlodge Farms Ltd | Agriculture & fishing | 2024 |
| Crownpoint Experts L.P. | | 2016 |
| Crownpoint Trade L.P. | | 2015 |
| Crozier Family | Professional & scientific | 2024 |
| Cryptic CMS Ltd | Administrative & support | 2025 |
| Cryptowave Ltd | Information & communication | 2021 |
| Crystal Finance (NI) Ltd | Real estate | 2014 |
| CSC Electrics Ltd | Construction | 2021 |
| Cscm Holdings Ltd | Wholesale & retail | 2016 |
| CSE Sales Ltd | Wholesale & retail | 2020 |
| Csgh Ltd | Financial services | 2023 |
| Csmit (N.I.) Ltd | Arts & recreation | 2019 |
| CSP (Newry) Ltd | Real estate | 2016 |
| CSP Trading (Newry) Ltd | Hospitality | 2016 |
| CT Electrical (IRE) Ltd | Construction | 2017 |
| CT1 Ltd | Wholesale & retail | 2006 |
| CTC Commercials Ltd | Wholesale & retail | 2024 |
| CTG Construction Services Ltd | Construction | 2019 |
| Ctrl-Intelligence Ltd | Extraterritorial | 2013 |
| Cuan Mhuire (NI) Limited | Health & social care | 1998 |
| Cubetecture Design Limited | Professional & scientific | 2019 |
| Cubex Holdings Limited | Financial services | 2025 |
| Cuchulainn Teamware Ltd | Manufacturing | 2015 |
| Cuhullan IT Solutions Limited | Wholesale & retail | 2025 |
| Culann Enterprises Ltd | Administrative & support | 2025 |
| Cullaville House Ltd | Wholesale & retail | 2012 |
| Cullen Funeralcare Ltd | Other services | 2025 |
| Cullenboy Contracts Ltd | Construction | 2021 |
| Cullion Point Advisory Ltd | Professional & scientific | 2025 |
| Culloville Cleaning Ltd | Wholesale & retail | 2025 |
| Culloville Development Association | Arts & recreation | 2011 |
| Cully Automation (UK) Limited | Manufacturing | 2017 |
| Cully Water Enterprises Ltd | Real estate | 2024 |
| Cully Water Ltd | Construction | 2021 |
| Cullyhanna Community Group | Other services | 2010 |
| Cumming Fitout Ltd | Construction | 2024 |
| Cunningham Butchers Ltd | Wholesale & retail | 2010 |
| Cunningham Contracts Holdings Ltd | Construction | 2018 |
| Cunningham Contracts Ltd | Construction | 2006 |
| Cunningham Food Ltd | Wholesale & retail | 2018 |
| Cunningham Properties (NI) Ltd | Wholesale & retail | 2016 |
| Curly Brae Farm Ltd | Agriculture & fishing | 2010 |
| Curo Software Ltd | Information & communication | 2012 |
| Curphey Plant Ltd | Wholesale & retail | 2018 |
| Curran Therapy and Training Ltd | Health & social care | 2018 |
| Current AV Ltd | Construction | 2025 |
| Curtis Concrete Solutions Limited | Construction | 1997 |
| Curves (Newry) Ltd | Arts & recreation | 2019 |
| Cusack Horology Ltd | Manufacturing | 2026 |
| Customised.Gifts Limited | Wholesale & retail | 2015 |
| CV21 Ltd | Professional & scientific | 2021 |
| CVS Commerce Limited | Wholesale & retail | 2024 |
| CW Garden Designs Ltd | Administrative & support | 2025 |
| CWK Contractors Ltd | Construction | 2020 |
| CWS Hygiene (NI) Limited | Administrative & support | 2015 |
| Cyber Anthem Ltd | Information & communication | 2026 |
| CZN Shopfitting Ltd | Manufacturing | 2017 |
| CÚ Chulainn Group Ltd | Agriculture & fishing | 2023 |
| Cúram Anaesthesiology | Health & social care | 2025 |
| D & B Safetycare Operations Ltd | Financial services | 2023 |
| D & C Accountancy Services Ltd | Professional & scientific | 2022 |
| D & E Homes Ltd | Real estate | 2024 |
| D & J Fuels Limited | Wholesale & retail | 1992 |
| D & L Retail Limited | Wholesale & retail | 2014 |
| D & T Electrical Installation (NI) Ltd | Construction | 2023 |
| D Boyle Contracts Ltd | Construction | 2024 |
| D Boyle Properties Ltd | Real estate | 2019 |
| D Doyle Plumbing & Heating Ltd | Construction | 2022 |
| D Farrell Carpentry Ltd | Construction | 2026 |
| D M a Sales and Marketing Ltd | Administrative & support | 2017 |
| D Maginn Construction Ltd | Construction | 2024 |
| D Murray Medical Limited | Health & social care | 2011 |
| D N Developments Limited | Construction | 2016 |
| D O'Hare (Rentals) Limited | Financial services | 2025 |
| D O'Sullivan (Print Supplies) UK Limited | Information & communication | 2019 |
| D Quinn Ltd | Wholesale & retail | 2021 |
| D Reel Plant Limited | Construction | 2015 |
| D&B Resources Ltd | Administrative & support | 2024 |
| D&B Safetycare (NI) Ltd | Wholesale & retail | 2020 |
| D&S Interior Contracts Limited | Construction | 2017 |
| D-Scaff Ireland Ltd | Construction | 2015 |
| D. Magennis Ltd | Professional & scientific | 2018 |
| D. Mallon Consulting Ltd | Professional & scientific | 2023 |
| D.B. Inspection Solutions Limited | Professional & scientific | 2006 |
| D.Doyle Contracts Ltd | Construction | 2022 |
| D.H. Oils Limited | Wholesale & retail | 1991 |
| D.R.A Consulting Services Limited | Professional & scientific | 2017 |
| D.S Mullen Ltd | Real estate | 2020 |
| Dairyglen Products Ltd | Hospitality | 2022 |
| Daisy Creran Limited | Real estate | 2021 |
| Daisy Hill Boarding Kennels Limited | Agriculture & fishing | 2021 |
| Daisy Newry Ltd | Wholesale & retail | 2002 |
| Daisy Property Management Ltd | Real estate | 2022 |
| Daisychain Daycare (NI) Limited | Other services | 2012 |
| Daleriver Limited | Energy | 2017 |
| Dallan Trading (Newry) Ltd | Wholesale & retail | 2025 |
| Dalton Importing Limited | Wholesale & retail | 2025 |