| Climahtech Compress Hypress Limited | Administrative & support | 2024 |
| Climahtech Sustainable Aviation Fuel Limited | Administrative & support | 2024 |
| Climate Design Studio Limited | Professional & scientific | 2018 |
| Climbni Rope Access Services Ltd | Construction | 2026 |
| Clinton Cards (Essex) Limited | | 1999 |
| Clinty BIO Limited | Manufacturing | 2024 |
| Clinty Chemicals Limited | Administrative & support | 1977 |
| Clinty Laboratories Limited | Professional & scientific | 2020 |
| Clinty Re-Gen Limited | Administrative & support | 1999 |
| Clip N Climb Dundonald Ltd | Arts & recreation | 2012 |
| Clisb Ltd | Real estate | 2025 |
| Clochar Limited | Financial services | 2018 |
| Clock Network Technology Limited | Wholesale & retail | 2025 |
| Clockhill Management Company Limited | Households | 2009 |
| Clocknot Ltd | Wholesale & retail | 2025 |
| Clockwise River Limited | Professional & scientific | 2018 |
| Cloco Retail Ltd | Wholesale & retail | 2018 |
| Clofulcx Limited | Wholesale & retail | 2025 |
| Cloghan Gardens Management Company Limited | Households | 2003 |
| Cloigh Limited | Wholesale & retail | 2022 |
| Cloisters Management (NI) Limited -the | Extraterritorial | 2001 |
| Clonard Monastery Youth Centre | Education | 2007 |
| Clonard Residents Association | Other services | 1991 |
| Clondara Group Ltd | Real estate | 2024 |
| Clondara Holdings Ltd | Households | 2022 |
| Clondara Property Ltd | Real estate | 2019 |
| Clondermot Wind Limited | Construction | 2008 |
| Clonlis Properties Ltd | Real estate | 2022 |
| Clonrose Developments (Ards) Limited | Financial services | 2017 |
| Clonrose Developments (Newry) Limited | Construction | 2014 |
| Clonrose Developments (Ormeau) Limited | Construction | 2017 |
| Clonrose Developments Limited | Construction | 2015 |
| Clonrose Group Limited | Financial services | 2011 |
| Clontallagh Estates Ltd | Construction | 2025 |
| Clontara Contracts Limited | Health & social care | 2022 |
| Clontara Holdings Limited | Real estate | 2016 |
| Clontara Limited | Health & social care | 2010 |
| Cloona Child Contact Centre Limited | Education | 2003 |
| Cloonty Windfarm Limited | Energy | 2010 |
| Clorisun Image Co Limited | Wholesale & retail | 2025 |
| Clothing Development Centre Limited | | 1990 |
| Cloud Business Ltd | Information & communication | 2024 |
| Cloud Cortex (2026) Ltd | Wholesale & retail | 2025 |
| Cloud Kids Limited | Wholesale & retail | 2024 |
| Cloud Mobilizd Ltd | Information & communication | 2018 |
| Cloud Operate Limited | Information & communication | 2011 |
| Clouddreamlighting Co Limited | Wholesale & retail | 2026 |
| Cloudforce Ltd | Wholesale & retail | 2022 |
| Cloudguard NI Ltd | Information & communication | 2026 |
| Cloudream Ltd | Wholesale & retail | 2024 |
| Cloudsmith Ltd | Information & communication | 2018 |
| Cloudsource Consulting Limited | Information & communication | 2018 |
| Cloudsource Holdings Ltd | Professional & scientific | 2021 |
| Cloughmore Properties Ltd | Real estate | 2019 |
| Cloumix Technology HK Limited | Wholesale & retail | 2026 |
| Clover Cable Company Ltd | Professional & scientific | 2015 |
| Clover Clarence Chambers Holdings Limited | Financial services | 2025 |
| Clover Clarence Chambers Opco Limited | Hospitality | 2025 |
| Clover Cleaning Group NI Ltd | Administrative & support | 2019 |
| Clover Contract Solutions Ltd | Construction | 2019 |
| Clover Pubs Holdings NI Limited | Financial services | 2018 |
| Clover Pubs NI NO.1 Limited | Hospitality | 2018 |
| Clover Pubs NI NO.2 Limited | Hospitality | 2019 |
| Clover Pubs NI NO.3 Limited | Hospitality | 2019 |
| Clover Pubs NI NO.4 Limited | Hospitality | 2019 |
| Clover Pubs NI NO.5 Limited | Hospitality | 2022 |
| Clover Pubs Property NI Limited | Real estate | 2022 |
| Clover Pubs Property NI NO.1 Limited | Real estate | 2024 |
| Clover Pubs Property NI NO.2 Limited | Real estate | 2024 |
| Cloverdale Merchants Limited | Extraterritorial | 2003 |
| Cloverhill Property Ltd | Real estate | 2025 |
| Clow Group Ltd | | 2001 |
| Clpeu NI Limited | Administrative & support | 2020 |
| Clpr Limited | Financial services | 2022 |
| Clss Palying Limited | Wholesale & retail | 2025 |
| Club 1896 Ltd | Other services | 2023 |
| Club Marketing Group Limited | Financial services | 2022 |
| Club Medals Limited | Manufacturing | 2024 |
| CLUB24FITNESS Lisburn Ltd | Arts & recreation | 2023 |
| CLUB4UP Limited | Health & social care | 2013 |
| Clubgrp Limited | Manufacturing | 2025 |
| Clubhouse Kitchen Limited | Hospitality | 2022 |
| Clubien Limited | Wholesale & retail | 2023 |
| Clyde & Co (Northern Ireland) LLP | | 2014 |
| Clyde Furnishing Belfast Ltd | Construction | 2026 |
| Clyde Shanks Limited | Professional & scientific | 2011 |
| Clythia Ltd | Manufacturing | 2025 |
| Clír Water Ltd | Manufacturing | 2025 |
| CM Aircraft Services Ltd | Manufacturing | 2022 |
| CM Capital Global Ltd | Hospitality | 2025 |
| CM Engineering Ltd | Wholesale & retail | 2025 |
| CM Fit-Out Ltd | Manufacturing | 2022 |
| CM Flips Ltd | Construction | 2026 |
| CM Law (NI) Limited | Professional & scientific | 2014 |
| CM Plant Hire Ltd | Construction | 2016 |
| CM Property Developments Ltd | Real estate | 2026 |
| CM Skips Limited | Water & waste | 2014 |
| Cmac Glazing Ltd | Construction | 2013 |
| Cmac N.I. Limited | Construction | 2021 |
| CMB Electrical Engineering Ltd | Construction | 2018 |