| Causeway Tower Ltd | Households | 2025 |
| Causeway Trust | Real estate | 2018 |
| Causeway Water Solutions Ltd | Water & waste | 2016 |
| Causeway Wind II Limited | Professional & scientific | 2013 |
| Causeway Wind Limited | Other services | 2012 |
| Cavanalee Wind Ltd | Energy | 2016 |
| Cavanreagh Limited | Hospitality | 2015 |
| Cave of World Limited | Wholesale & retail | 2025 |
| Cavehill Accountancy Ltd | Professional & scientific | 2024 |
| Cavehill Cloud Consulting Ltd | Information & communication | 2026 |
| Cavehill Mews Limited | Households | 2008 |
| Cavehill Psychology Ltd | Administrative & support | 2025 |
| Cavehill Redbarn Ltd | Other services | 2025 |
| Cavehill Retail Limited | Wholesale & retail | 2015 |
| Cavehill View Financial Services Ltd | Financial services | 2024 |
| Cavendish Electrical Limited | Construction | 2021 |
| Cavendish Property Limited | Real estate | 2025 |
| Cavity Corner Ltd | Health & social care | 2014 |
| Cawlands Limited | Real estate | 2016 |
| Cawodse Ltd | Wholesale & retail | 2025 |
| CB SME Holdings Limited | Professional & scientific | 2010 |
| CB Solutions IRE Ltd | Professional & scientific | 2025 |
| Cbcr Staffing Ltd | Administrative & support | 2025 |
| CBD Industries Ltd | Administrative & support | 2018 |
| CBD Payment Processing Limited | Financial services | 2023 |
| CBE Technical Solutions Limited | Information & communication | 2019 |
| Cbfpalo Ltd | Wholesale & retail | 2024 |
| CBK Builders Ltd | Wholesale & retail | 2017 |
| Cbrni Ltd | Wholesale & retail | 2021 |
| CBS Professional Services Ltd | Professional & scientific | 2017 |
| CBT Corporate Ltd | Financial services | 2023 |
| CC Electrical Contracts Ltd | Construction | 2024 |
| CC SME Holdings Ltd | Construction | 2018 |
| CC SME Investments Ltd | Financial services | 2025 |
| CCB Enterprises Limited | Education | 1993 |
| Cccuk Limited | Wholesale & retail | 2024 |
| CCD Transport (N.I.) Limited | Transport & logistics | 2018 |
| Ccgg Ltd | Real estate | 2024 |
| CCI Belfast Ltd | Information & communication | 2004 |
| Ccjk Limited | Hospitality | 2020 |
| CCK Trans Ltd | Administrative & support | 2017 |
| CCL Fire Protection Limited | Construction | 2021 |
| CCL Fitout Limited | Construction | 2018 |
| CCL Interiors Limited | Construction | 1974 |
| CCL Joinery Limited | Construction | 2021 |
| CCL Label Ireland Limited | Manufacturing | 2001 |
| CCR Automotive Ltd | Wholesale & retail | 2023 |
| CCR Roofing Ltd | Construction | 2025 |
| Ccrb Developments Ltd | Real estate | 2021 |
| Ccrc Design Ltd | Professional & scientific | 2020 |
| CCS Executive Coaches Limited | Transport & logistics | 2017 |
| CCS Residential Properties Limited | Real estate | 2013 |
| CCS Surveying Ltd | Extraterritorial | 2003 |
| Ccserv Ltd | Professional & scientific | 2022 |
| Ccsmor Limited | Wholesale & retail | 2019 |
| CCT Engineering Ltd | Construction | 2013 |
| Ccts EOT Limited | Financial services | 2024 |
| Ccuc Ltd | Health & social care | 2025 |
| CD Cars Ltd | Wholesale & retail | 2024 |
| CD Investments (N.I.) Limited | Financial services | 2016 |
| CD Plumbing & GAS Services Ltd | Construction | 2020 |
| CD Property Holdings (NI) Limited | Real estate | 2025 |
| CDC (NI) Ltd | Real estate | 1996 |
| CDC Design Group Ltd | Professional & scientific | 2024 |
| CDF Financial Limited | Real estate | 2015 |
| CDG Transport International Ltd | Transport & logistics | 2020 |
| CDG Transport Ltd | Transport & logistics | 2017 |
| Cdlm Contracts Ltd | Construction | 2024 |
| CDM (NI) Ltd | Health & social care | 2012 |
| CDS City Radar Limited | Information & communication | 2017 |
| CDS New Ventures Ltd | Information & communication | 2014 |
| CE Canning's Quality Company Ltd | Professional & scientific | 2018 |
| CE Promotions Limited | Arts & recreation | 2016 |
| Ceara Court Management Company Limited | Households | 1989 |
| Ceased Trading NI655051 Limited | Health & social care | 2018 |
| Ceasefire Films Limited | Information & communication | 2026 |
| Ceathru Consulting Limited | Professional & scientific | 2024 |
| Cecil Smyth Limited | Construction | 1972 |
| Cecil's Way Limited | Health & social care | 2022 |
| Ceco (Flooring) Limited | Construction | 1978 |
| Cedar Foundation - the | Health & social care | 1946 |
| Cedar Grove Veterinary Clinic Limited | Extraterritorial | 2011 |
| Cedar View Management Company Limited | Households | 2007 |
| Cedareast Investments Limited | Real estate | 1994 |
| Cedarhurst Apartments Limited | Extraterritorial | 1988 |
| Cedarmount Properties Limited | Professional & scientific | 2002 |
| Cedaroak Investments Limited | Extraterritorial | 1991 |
| Cedarr Capital Group Limited | Real estate | 2017 |
| Cedarr Properties Limited | Real estate | 2013 |
| Cedarr Trading and Investments Limited | Real estate | 2011 |
| Cedars Accountants Global Ltd | Professional & scientific | 2025 |
| Cedars Residential Limited | Real estate | 2014 |
| Cedarville Limited | Construction | 2014 |
| Cedona Limited | Construction | 2015 |
| Ceenwood Ltd | Manufacturing | 2021 |
| Cefa-Soft Limited | Information & communication | 1982 |
| Ceirníní Crua Ltd | Information & communication | 2025 |
| CEK Property Limited | Real estate | 2013 |
| Celebrate Sun Limited | Wholesale & retail | 2023 |
| Cellarbar FM Limited | Manufacturing | 2015 |