| Castle Gardens Preschool Limited | Health & social care | 2024 |
| Castle MC Holdings Ltd | Financial services | 2019 |
| Castle Meadows Investments Limited | Construction | 2013 |
| Castle Mews Management (NO.2) Limited | Households | 1987 |
| Castleavery Limited | Real estate | 2017 |
| Castlebawn Dental Practice Limited | Health & social care | 2010 |
| Castlefrances Limited | Hospitality | 2018 |
| Catefung Limited | Wholesale & retail | 2024 |
| Cattogs Lane Residents Limited | Extraterritorial | 2008 |
| Causeway Property Developments Limited | Construction | 2006 |
| Cavero Strategies Limited | Professional & scientific | 2026 |
| Cbbdec Limited | Wholesale & retail | 2025 |
| CBT Counselling Services Ltd | Health & social care | 2016 |
| CCP Composites Ltd | Manufacturing | 2017 |
| CDP Estates Limited | Financial services | 2025 |
| Cedar P&I Limited | Real estate | 2018 |
| Celebrity Developments Limited | Construction | 1998 |
| Cenfox Limited | Wholesale & retail | 2024 |
| CFC Comber Ltd | Hospitality | 2011 |
| CFR 75 Limited | Real estate | 2014 |
| Chacha Hair Products Ltd | Manufacturing | 2019 |
| Chambers Contracts Limited | Construction | 2014 |
| Charging Network Ltd | Energy | 2019 |
| Charlotte Colt Investment Ltd | Wholesale & retail | 2023 |
| Chasing Song Limited | Wholesale & retail | 2024 |
| Chef & Manager Ltd | Hospitality | 2019 |
| Chenbo Ltd | Wholesale & retail | 2025 |
| Chengzhenliang Limited | Wholesale & retail | 2024 |
| Chenpengxu Limited | Wholesale & retail | 2025 |
| Chenqiaosheng Limited | Wholesale & retail | 2025 |
| Chensuyang Limited | Wholesale & retail | 2025 |
| Chenxuefen Limited | Wholesale & retail | 2025 |
| Cherat Limited | Hospitality | 2025 |
| Cherry Wellbeing Ltd | Health & social care | 2026 |
| Cherryburn Management Company Limited | Households | 2009 |
| CHI Solutions Ltd | Information & communication | 2022 |
| Chiemsee Consultancy Ltd | Agriculture & fishing | 2022 |
| Chit ONN Limited | Wholesale & retail | 2025 |
| CHJ Property Investments Ltd | Real estate | 2016 |
| Chloelouisetgnde Limited | Wholesale & retail | 2024 |
| Choco Tower Limited | Wholesale & retail | 2025 |
| Choice Pizza Limited | Manufacturing | 2011 |
| Chrangaoyangderetail Limited | Wholesale & retail | 2025 |
| Chris J Burrell Ltd | Wholesale & retail | 2025 |
| Christian Guidelines Limited | Other services | 2001 |
| Christopher Mckee Ltd | Wholesale & retail | 2023 |
| Chtanopes Limited | Wholesale & retail | 2025 |
| Chunfeng Limited | Wholesale & retail | 2023 |
| Churchstone Lodge Management Limited | Households | 2002 |
| Churchvale Investments Ltd | Financial services | 2024 |
| Cibus Technologies Ltd | Information & communication | 2024 |
| Ciggie Shop (NI) Ltd | Wholesale & retail | 2015 |
| Cilily Limited | Wholesale & retail | 2024 |
| Cinepunked Ltd | Information & communication | 2019 |
| Circa 97 Games Ltd | Information & communication | 2025 |
| Cisum Ltd | Real estate | 2015 |
| CJM Facilities Management Ltd | Construction | 2025 |
| CJN Lettings Ltd | Real estate | 2025 |
| Cjta Treasures Ltd | Wholesale & retail | 2025 |
| Claire Josserand Ltd | Professional & scientific | 2023 |
| Clana Tone Limited | Wholesale & retail | 2025 |
| Classic Blinds Belfast Limited | Wholesale & retail | 2015 |
| Claymore Digital Ltd | Information & communication | 2022 |
| Clear Clouds Trade Ltd | Wholesale & retail | 2024 |
| Climate Tactics Ltd | Wholesale & retail | 2021 |
| Cloud Link Pro Ltd | Wholesale & retail | 2025 |
| Cloud N9NE Ards Ltd | Wholesale & retail | 2025 |
| Cloughey Heritage Group Limited | Real estate | 2024 |
| Cmcaudio Ltd | Information & communication | 2022 |
| CMH Haulage Ltd | Transport & logistics | 2025 |
| Cnloon Trading Limited | Wholesale & retail | 2023 |
| CNM Property Limited | Real estate | 2021 |
| Cnrw Automotive Ltd | Wholesale & retail | 2026 |
| Coach Connections Ireland Ltd | Transport & logistics | 2022 |
| Coach Cycles Comber Limited | Administrative & support | 2019 |
| Coan Coffee Limited | Hospitality | 2022 |
| Coastal Goods Ltd | Wholesale & retail | 2024 |
| Coasteering NI Ltd | Arts & recreation | 2023 |
| Coastline Caravans Limited | Extraterritorial | 1981 |
| Coastquarter Developments NI Ltd | Construction | 2023 |
| Coding Fury Limited | Information & communication | 2012 |
| Coffee Refresh Ltd | Professional & scientific | 2025 |
| Coffey Construction Solutions Ltd | Construction | 2019 |
| Colin Adams Motor Parts Holdings Limited | Financial services | 2021 |
| Colin Adams Motor Parts Limited | Wholesale & retail | 2006 |
| Colin Armstrong Ltd | Wholesale & retail | 2025 |
| Colonel Paddy's Cafe Ltd | Wholesale & retail | 2025 |
| Colourpoint Creative Limited | Information & communication | 2012 |
| Comber Building Services LLP | | 2010 |
| Comber Distilleries Co. Limited | Extraterritorial | 1978 |
| Comber Pizza Ltd | Hospitality | 2025 |
| Comber Properties Ltd | Real estate | 2019 |
| Comber Regeneration Community Partnership Ltd. | Other services | 2004 |
| Comber Tandoori Limited | Hospitality | 2013 |
| Comber Youth for Christ Limited | Health & social care | 2007 |
| Commercial Property Solutions Ltd | Real estate | 2004 |
| Companionship Matters Ltd | Health & social care | 2017 |
| Composite Deck Company Limited | Construction | 2019 |
| Composite Dynamics Ltd | Manufacturing | 2019 |
| Coney Consultancy Group Ltd | Information & communication | 2019 |