| Canning Engineering Ltd | Manufacturing | 2021 |
| Cannon Motors Limited | Wholesale & retail | 2006 |
| Capelli 2(NI) Ltd | Other services | 2016 |
| Captivating Landscapes Limited | Professional & scientific | 2024 |
| Carleton Bridge Mews Management Company Limited | Households | 2022 |
| Carmichael Logistics Limited | Transport & logistics | 2012 |
| Carnreagh Park Management Company Limited | Households | 2018 |
| Carnroe Drive 1960 Limited | Extraterritorial | 2014 |
| Carrick Competitions Limited | Information & communication | 2023 |
| Carrick Eats Limited | Hospitality | 2023 |
| Carrick Electrical Services Limited | Manufacturing | 2026 |
| Carrick EYE Care Ltd | Wholesale & retail | 2021 |
| Carrick Fleet Solutions Ltd | Wholesale & retail | 2025 |
| Carrick Marine Projects Limited | Manufacturing | 2020 |
| Carrick Services Group Ltd | Manufacturing | 2018 |
| Carrickburn Mews Limited | Households | 1996 |
| Carrickfergus Amateur Rowing Club Incorporating Carrickfergus Sailing Club Limited | Arts & recreation | 2011 |
| Carrickfergus and Larne Child Contact Centre Ltd | Health & social care | 2014 |
| Carrickfergus Community Forum | Other services | 2011 |
| Carrickfergus Integrated Primary School Limited | Education | 1992 |
| Carrickfergus Vineyard Church | Other services | 2010 |
| Carrickfergus Young Mens Christian Association | Health & social care | 2004 |
| Carson Engineering Specialists Ltd | Professional & scientific | 2025 |
| Cartlidge & Partners Ltd | Professional & scientific | 2023 |
| Casey Enterprises Ltd | Financial services | 2024 |
| Castle Homecare Ltd | Health & social care | 2023 |
| Castle Ventilation Ltd | Manufacturing | 2020 |
| Castlebridge Court Management Limited | Real estate | 1990 |
| Castlefergus Properties Limited | Real estate | 2017 |
| Castlegrange Maintenance Management Limited | Households | 2001 |
| Castlehill Estate Management Company Limited | Households | 2007 |
| Caters Carrick Limited | Real estate | 1973 |
| Cathford Consultancy Services Ltd | Professional & scientific | 2023 |
| Causeway Networks Ltd | Information & communication | 2011 |
| Caven's Extra Hands Ltd | Manufacturing | 2011 |
| CBM Trading Company Ltd | Wholesale & retail | 2021 |
| CC Motors (NI) Ltd | Wholesale & retail | 2014 |
| CCG Catering Ltd | Hospitality | 2024 |
| Ccic Enterprises Ltd | Administrative & support | 2021 |
| CCR (N.I.) Ltd | Financial services | 2026 |
| Centre of Excellence in Psychological Therapies Ltd | Health & social care | 2023 |
| Centrepoint Property Solutions Ltd | Hospitality | 2023 |
| Chapel Buildings Management Company Limited | Households | 2005 |
| Cherryville View Management Company Ltd | Households | 2024 |
| China Garden Carrickfergus Ltd | Hospitality | 2023 |
| Chogg Production Ltd | Administrative & support | 2020 |
| Chris MC KEE Coaching Ltd | Other services | 2026 |
| Christ the Redeemer, International Ministries | Other services | 2009 |
| Chrysalis Salons Ltd | Other services | 2025 |
| Chunk N Cheese Limited | Hospitality | 2025 |
| Circuitflow Compliance Limited | Information & communication | 2025 |
| Civil and Structural Computer Services Limited | Information & communication | 1986 |
| CK Enterprises (NI) Ltd | Administrative & support | 2014 |
| Clann Connections Ltd | Professional & scientific | 2025 |
| Clarity Financial Limited | Financial services | 2022 |
| Clarrick Property Limited | Real estate | 2013 |
| Classic and Collectable Club Insurances Limited | Extraterritorial | 1998 |
| Classique Fireplaces Ltd | Construction | 2021 |
| Classy Games Studios Ltd | Information & communication | 2023 |
| Clean Slate Exteriors NI Ltd | Administrative & support | 2026 |
| Clear Solutions (N.I.) Ltd | Administrative & support | 2021 |
| Clearpool Ltd | Information & communication | 2014 |
| Clearpool Technologies Ltd | Information & communication | 2012 |
| Cleaver and Steel Limited | Manufacturing | 2017 |
| Cli's Secret Ltd | Arts & recreation | 2023 |
| Cli's Secret Online Ltd | Arts & recreation | 2024 |
| Cliff Aerospace Ltd | Manufacturing | 2024 |
| Clis Secret 10 Ltd | Arts & recreation | 2024 |
| Clocktower Cafe(Ni) Ltd | Hospitality | 2026 |
| Cloud N9NE Ltd | Wholesale & retail | 2024 |
| Cloud Voice Networks Ltd | Information & communication | 2025 |
| Cloughlands Park Ltd | Real estate | 2021 |
| CM Aerospace Ltd | Manufacturing | 2015 |
| CMA Moss Ltd | Real estate | 2019 |
| CMB Software Services Limited | Information & communication | 2020 |
| Cmcl Contracting Ltd | Manufacturing | 2017 |
| Cmpr Talent Ltd | Administrative & support | 2014 |
| Co-It Ltd | Construction | 2023 |
| Cole Management (Eden) Limited | Professional & scientific | 1988 |
| Colorshow Limited | Professional & scientific | 2018 |
| Comber Court Management Company Limited | Households | 2001 |
| Comercial Puig Alarcon Ltd | Wholesale & retail | 2025 |
| Commercial Charter Boats Northern Ireland Ltd | Transport & logistics | 2023 |
| Commercial Insurance Services Direct Ltd | Professional & scientific | 2007 |
| Compliance Switching Solutions Limited | Manufacturing | 2025 |
| Connor Court Apartments Limited | Real estate | 2013 |
| Conpath Limited | Health & social care | 2026 |
| Consultant Aero Services Ltd | Manufacturing | 2019 |
| Coral Isle of MAN Ltd | Professional & scientific | 2019 |
| Cosain Ltd | Administrative & support | 2021 |
| Coulter Manufacturing Solutions Ltd | Professional & scientific | 2024 |
| County Antrim Yacht Club Limited | Arts & recreation | 2012 |
| Cova AER Ltd | Manufacturing | 2022 |
| Cover.Net Limited | Information & communication | 1995 |
| CP2 Food Hub Limited | Hospitality | 2020 |
| CR Building Solutions (N.I.) Ltd | Construction | 2023 |
| Craig Financial Assets Management Ltd | Real estate | 2025 |
| Craigowen Engineering Limited | Manufacturing | 2017 |
| Cranston Commerce Limited | Wholesale & retail | 2024 |
| CREATIV3 Merchandise Ltd | Information & communication | 2012 |