| Butyl Systems Ireland Ltd | Construction | 2006 |
| Byrne Green Energy Ltd | Energy | 2016 |
| C & a Mechanical Ltd | Construction | 2015 |
| C & D Contracts (N.I.) Ltd | Construction | 2022 |
| C & D Flooring Limited | Construction | 2014 |
| C & M Developments (NI) Limited | Construction | 2006 |
| C & M Motors Ltd | Wholesale & retail | 2011 |
| C Circu Ltd | Health & social care | 2015 |
| C Conway Electrical & General Maintenance Ltd | Construction | 2022 |
| C Mccann Properties Ltd | Real estate | 2022 |
| C Mcgarvey Groundworks Ltd | Construction | 2023 |
| C O'Neill Ltd | Extraterritorial | 2012 |
| C&M Business Park Ltd | Real estate | 2018 |
| C&M Group Ltd | Financial services | 2025 |
| C&M Motorsport Ltd | Wholesale & retail | 2018 |
| C&M Retail Holdings Ltd | Real estate | 2016 |
| C&R Plant Ltd | Wholesale & retail | 2021 |
| C&S Parts Limited | Professional & scientific | 2014 |
| C&S Precision ENG Ltd | Manufacturing | 2014 |
| C-More Flying School Limited | Education | 2013 |
| C2 Remarketing Ltd | Wholesale & retail | 2019 |
| C3 Remarketing Ltd | Wholesale & retail | 2024 |
| Cabcon Ltd | Construction | 2024 |
| Cado Homes Ltd | Real estate | 2020 |
| Cafe Sásta Ltd | Hospitality | 2025 |
| Caffe Fresco Ireland Ltd | Hospitality | 2011 |
| Cafima Group Ltd | Financial services | 2024 |
| Cairn Fit-Out Ltd | Construction | 2013 |
| Cairnview Studio CIC | Health & social care | 2026 |
| Calbro Construction (NI) Ltd | Construction | 2005 |
| Calbro Holdings Ltd | Financial services | 2024 |
| Calbro Properties Ltd | Real estate | 2024 |
| Cald Construction Ltd | Construction | 2025 |
| Caldwell Holdings Ltd | Financial services | 2023 |
| Caldwell Motor Factors Limited | Wholesale & retail | 2003 |
| Calgagh Farm Ltd | Agriculture & fishing | 2023 |
| Callagheen Ltd | Energy | 2017 |
| CAM Cabs Dromore Ltd | Transport & logistics | 2024 |
| Camalia Limited | Agriculture & fishing | 2013 |
| Cambrian Developments Limited | Construction | 1997 |
| Camcar Developments Ltd | Construction | 2022 |
| Camlough Plant Ltd | Construction | 2021 |
| Camowen Holding Co Limited | Financial services | 2022 |
| Camowen Partnership Ltd | Other services | 1996 |
| Camowen Partnership Trust | Health & social care | 2003 |
| Campbell & Slevin Developments Limited | Construction | 2014 |
| Campbell Earthworks Ltd | Construction | 2020 |
| Campbell Electrics Ltd | Construction | 2024 |
| Campbell Financial NI Ltd | Financial services | 2022 |
| Campbell Motors Ltd | Wholesale & retail | 2016 |
| Camphill Community Clanabogan | Health & social care | 1985 |
| Campsie Service Station Limited | Wholesale & retail | 2013 |
| Capital Reinforcing (Ireland) Limited | Manufacturing | 2002 |
| Cappagh Farms Ltd | Agriculture & fishing | 2021 |
| Car Sales NI Limited | Wholesale & retail | 2015 |
| Car Transport (N.I.) Ltd | Construction | 2017 |
| Cara Telecom Ltd | Information & communication | 2020 |
| Carben Controls Ltd | Professional & scientific | 2023 |
| Cardboard Boxes (N.I.) Ltd | Manufacturing | 2015 |
| Care for Cancer | Other services | 2023 |
| Carland Contracts Ltd | Construction | 2020 |
| Carland Plant Hire Ltd | Administrative & support | 2023 |
| Carmelas Hair Ltd | Other services | 2024 |
| Carmen Properties Limited | Real estate | 2020 |
| Carnalea House Limited | Construction | 2018 |
| Carnalea Properties Ltd | Real estate | 2022 |
| Carngreen Limited | Wholesale & retail | 2019 |
| Carnony Holdings Limited | Real estate | 2017 |
| Carpet Cleaning N.I. Ltd | Extraterritorial | 2024 |
| Carrick Hill Management Ltd | Households | 2021 |
| Carrick Homes Ltd | Real estate | 2018 |
| Carrickrock Holdings Ltd | Financial services | 2020 |
| Carrig Investments Limited | Real estate | 2002 |
| Carrowkeel Farms Limited | Agriculture & fishing | 2026 |
| Cartin Engineering Limited | Manufacturing | 2016 |
| CAS Apex Holdings Ltd | Financial services | 2023 |
| Cashlin Pubs Ltd | Hospitality | 2025 |
| Cashty Property Limited | Real estate | 2016 |
| Cashty Quarry Ltd | Mining & quarrying | 2022 |
| Casorna Contracts Ltd | Construction | 2026 |
| Cass Partnership Ltd | Real estate | 2014 |
| Castle Dental Studio (NI) Ltd | Health & social care | 2014 |
| Castle Irvine Estate Limited | Real estate | 2020 |
| Castle Paving Ireland Ltd | Construction | 2007 |
| Castle Paving Northern Ireland Ltd | Financial services | 2014 |
| Castle Paving Products Ltd | Manufacturing | 2018 |
| Castle Retail Trading Ltd | Wholesale & retail | 2011 |
| Castlegore Wind Farm Ltd | Energy | 2015 |
| Castlemurray Farms Limited | Agriculture & fishing | 2014 |
| Castletown Square Management Company Ltd | Real estate | 2005 |
| Cathal Gormley & Co Ltd | Professional & scientific | 2010 |
| Catholic Mothers Ireland Ltd | Other services | 2023 |
| Cathy 90S Ltd | Hospitality | 2018 |
| Catmar Holdings Limited | Real estate | 2016 |
| Cavanacaw FP Ltd | Real estate | 2026 |
| Cavanreagh Farms Limited | Agriculture & fishing | 2019 |
| CB Plant & Sales Ltd | Administrative & support | 2017 |
| CC Holding Company (NI) Ltd | Financial services | 2019 |
| CC Property Company (NI) Ltd | Real estate | 2019 |
| CC Wind Services Ltd | Manufacturing | 2026 |