| Clonfad Farms Limited | Agriculture & fishing | 2011 |
| Clonkee Farms Ltd | Agriculture & fishing | 2023 |
| Cloon Construction Ltd | Construction | 2022 |
| CLOUD9DIGITAL Media Ltd | Information & communication | 2014 |
| Clougher Distribution Ltd | Wholesale & retail | 2009 |
| Clovervale Enterprises Limited | Real estate | 2011 |
| Club Draws Limited | Other services | 2022 |
| Cluideen Meadows Ltd | Hospitality | 2024 |
| CM Drum Ltd | Construction | 2024 |
| Cmac Holdco Limited | Professional & scientific | 2014 |
| Cmag Limited | Financial services | 2023 |
| Coalter Co Limited | Financial services | 2026 |
| Coba Properties Ltd | Construction | 2024 |
| Cobra Dual Controls Limited | Manufacturing | 2025 |
| Code Electrical Automation (UK) Limited | Construction | 2020 |
| Coldrum Holdings Ltd | Financial services | 2021 |
| Cole Culture Limited | Real estate | 2014 |
| College Park Lane Management Company Limited | Households | 2015 |
| Colsen Contracts Limited | Agriculture & fishing | 2015 |
| Colton Quarries Lack Limited | Mining & quarrying | 2020 |
| Combined Caving and Diving Club Ltd | Arts & recreation | 2025 |
| Comfy Pillows Limited | Households | 2020 |
| Community Advice Fermanagh Ltd | Other services | 2010 |
| Conerick Power Limited | Energy | 2013 |
| Conmuto Limited | Wholesale & retail | 2020 |
| Connect Green Energy Limited | Financial services | 2011 |
| Connolly Brothers Haulage Ltd | Transport & logistics | 2021 |
| Conor Corry Limited | Financial services | 2008 |
| Conor Developments Limited | Real estate | 1996 |
| Conor Donnelly Contracts Ltd | Transport & logistics | 2025 |
| Conor Dunne Livestock Ltd | Agriculture & fishing | 2022 |
| Consiliarii Ltd | Professional & scientific | 2024 |
| Construct Direct Limited | Professional & scientific | 2010 |
| Constructiveflow Ltd | Information & communication | 2024 |
| Convey Engineering Services Limited | Construction | 2015 |
| Conwell Contracts (UK) Limited | Construction | 2006 |
| Coolaness Rentals Ltd | Hospitality | 2022 |
| Coolarne Civils Ltd | Wholesale & retail | 2022 |
| Coole Ltd | Professional & scientific | 2025 |
| Coolhill Limited | Real estate | 2006 |
| Coolsky Software Ltd | Information & communication | 2024 |
| Cooper Investment (NI) Limited | Real estate | 2013 |
| Cooper Wilkinson Limited | Professional & scientific | 2014 |
| Core Connections Limited | Energy | 2025 |
| Coreview Consultancy Ltd | Professional & scientific | 2025 |
| Corlough Trading Ltd | Wholesale & retail | 2025 |
| Cornavray Holdings Ltd | Financial services | 2026 |
| Cornerstone Capital and Investments Limited | Financial services | 2013 |
| Corralea Activity Centre Limited | Arts & recreation | 2004 |
| Corrard Game Shoot Ltd | Agriculture & fishing | 2009 |
| Country House Town House Limited | Wholesale & retail | 2017 |
| County Fermanagh Farming Society Limited | Other services | 2004 |
| County Trust Limited | Other services | 1992 |
| Cove 22 Ltd | Hospitality | 2014 |
| COX Foodmarkets Ltd | Wholesale & retail | 2003 |
| CPD Plant Limited | Wholesale & retail | 2024 |
| Crane Trans Recovery Ltd | Transport & logistics | 2019 |
| Crann Energy Ltd | Agriculture & fishing | 2011 |
| Crawford Car Sales (N.I.) Ltd | Wholesale & retail | 2015 |
| Crawfords Marina Ltd | Wholesale & retail | 2017 |
| Creagh House Ltd | Hospitality | 2025 |
| Croaghcross Holdings Ltd | Construction | 2022 |
| Croga Consultancy Ltd | Professional & scientific | 2023 |
| Croissant Run Club Ltd | Wholesale & retail | 2024 |
| Cronin Investments Limited | Financial services | 2025 |
| Cronin Properties Limited | Real estate | 1999 |
| Crossfit Unify Ltd | Arts & recreation | 2022 |
| Crossroads Fuels Ltd | Wholesale & retail | 2010 |
| Crott Road Monea Management Limited | Real estate | 2006 |
| Crowline Enterprises Limited | Transport & logistics | 2001 |
| Crownhall Enterprises Limited | Wholesale & retail | 2013 |
| Crust & Crumb Breads Ltd | Manufacturing | 2022 |
| Crust & Crumb Properties Ltd | Real estate | 2023 |
| Crux Safety Ltd | Professional & scientific | 2021 |
| CS Block Work Limited | Construction | 2026 |
| CSF International Ltd | Manufacturing | 2023 |
| CT Enniskillen Ltd | Wholesale & retail | 2024 |
| Cuba Distribution Ltd | Wholesale & retail | 2016 |
| Cuilcagh Cottages Ltd | Hospitality | 2021 |
| Cuilcagh View Farm Limited | Agriculture & fishing | 2024 |
| Cullen Construction and Joinery Limited | Manufacturing | 2025 |
| Cullenjoinery Ltd | Manufacturing | 2019 |
| Cullion Properties Limited | Real estate | 2005 |
| Culliondoo Farms Ltd | Agriculture & fishing | 2025 |
| Cunningham Construction Services Limited | Construction | 2015 |
| Curam NUA (NI) Ltd | Financial services | 2022 |
| Curran Bars Ltd | Hospitality | 2021 |
| Currency Xtra Limited | Other services | 2008 |
| Curry Plumbing Services Limited | Construction | 2015 |
| Curryann Properties Ltd | Real estate | 2026 |
| Cutting Edge Helicopter Maintenance Ltd | Manufacturing | 2020 |
| Cuttz Cartel Ltd | Manufacturing | 2025 |
| CVC Technologies Ltd | Information & communication | 2011 |
| Cyberia Ireland Ltd | Transport & logistics | 2018 |
| Cynestx Ltd | Administrative & support | 2025 |
| D Breslin Haulage Ltd | Transport & logistics | 2019 |
| D Evans Assemblies Limited | | 1996 |
| D M Trading Solutions Limited | Wholesale & retail | 2014 |
| D R Refrigeration and Air Conditioning Ltd | Manufacturing | 2012 |
| D S Mcdermott Financial Planning Ltd | Financial services | 2019 |