| Belfast Power - to - X Ltd | Professional & scientific | 2008 |
| Belfast Waterside Partnership Limited | Construction | 2023 |
| BEN Ferris Ltd | Other services | 2017 |
| BEN Tilney Academy & Sporting Group Ltd | Arts & recreation | 2025 |
| Bere Rock Limited | Construction | 2015 |
| Bere Rock Services Ltd | Extraterritorial | 2020 |
| Besassured Properties Limited | Households | 1993 |
| Best Lets (N.I.) Ltd | Real estate | 2020 |
| Best Property Sales NI Ltd | Real estate | 2024 |
| Bioresources Management Limited | Water & waste | 2023 |
| BJG Solutions Ltd | Manufacturing | 2024 |
| Black Arch Distillery Ltd | Manufacturing | 2020 |
| Black Oak Accountancy Ltd | Professional & scientific | 2022 |
| Blackwater Electricity Limited | Energy | 2000 |
| Blackwood & Crawford Ltd | Construction | 2026 |
| Blairmount Ltd | Agriculture & fishing | 2023 |
| Blazin Digital Limited | Information & communication | 2013 |
| Blossoms (N.I.) Limited | Agriculture & fishing | 2019 |
| Blue Aero (N.I.) Ltd | Manufacturing | 2018 |
| Bluesafe Holdings Limited | Water & waste | 2025 |
| BMK (N.I.) Ltd | Energy | 2023 |
| BOB Slots Limited | Professional & scientific | 2023 |
| Bocm Ltd | Construction | 2026 |
| Boiler Cure NI Ltd | Construction | 2016 |
| Boiler Safe (N.I.) Ltd | Other services | 2018 |
| Bombay Spice (Lisnaskea) Limited | Hospitality | 2011 |
| Bouma Limited | Professional & scientific | 2015 |
| BPC Ventilation Limited | Construction | 2011 |
| Brae Developments Ltd | Construction | 2022 |
| Brian a Todd & Co Ltd | Real estate | 2015 |
| Brian Humphrys Haulage Ltd | Transport & logistics | 2008 |
| Broadways Private Nursing Home Ltd | Health & social care | 2017 |
| Brolis Photonics Solutions Ltd | Manufacturing | 2015 |
| BSB Engineering Solutions Ltd | Professional & scientific | 2019 |
| Bscc Ltd | Wholesale & retail | 2018 |
| BTC (N.I.) Ltd | Hospitality | 2023 |
| BUA Ireland Ltd | Wholesale & retail | 2026 |
| Burke Rentals Ltd | Real estate | 2020 |
| Business-Led (Northern Ireland) Ltd | Administrative & support | 2013 |
| C Kelly Electrical Limited | Construction | 2007 |
| C&Mm Residential Ltd. | Real estate | 2023 |
| CAD (N.I.) Ltd | Administrative & support | 2018 |
| Cafe Smart Ltd | Hospitality | 2015 |
| Caldera Services Ltd | Construction | 2018 |
| Caldera Solutions Ltd | Professional & scientific | 2018 |
| Calling Productions Ltd | Information & communication | 2021 |
| Cambrai Developments Limited | Real estate | 2006 |
| Cambridge & Co., Limited, | Real estate | 1910 |
| Campbell Geotech Ltd | Construction | 2022 |
| Candystore Studios Limited | Professional & scientific | 2025 |
| Capriole Energy Limited | Manufacturing | 2024 |
| Car and Commercial Smart Repair Ltd | Wholesale & retail | 2024 |
| Carbon Mineralization Limited | Manufacturing | 2024 |
| Carbonmineralisation Limited | Manufacturing | 2025 |
| Carbstone Limited | Water & waste | 2026 |
| Cardwell & Lynd Properties Limited | Real estate | 2022 |
| Carnbuck Energy Limited | Energy | 2022 |
| Caroline Girvan Ltd | Arts & recreation | 2020 |
| Carpe Omnia Ltd | Information & communication | 2012 |
| Carrick Hair Company Ltd | Other services | 2016 |
| Carrickfergus and District Motorcycle Club Limited | Arts & recreation | 2007 |
| Carryduff Vapes Ltd | Wholesale & retail | 2024 |
| Caruby Solutions Ltd | Construction | 2019 |
| Carved at the Castle Ltd | Manufacturing | 2021 |
| Castlerock Residential Limited | Real estate | 2022 |
| Castlevale Joinery Ltd | Construction | 2013 |
| Caterpillar (NI) Limited | Manufacturing | 1966 |
| CB (N.I.) Ltd | Hospitality | 2019 |
| CCI (N.I.) Ltd | Hospitality | 2026 |
| CCW (N.I.) Ltd | Wholesale & retail | 2024 |
| CD Mechanical Services Ltd | Construction | 2020 |
| CEL Services (N.I.) Ltd | Construction | 2024 |
| Central Garage Larne Ltd | Professional & scientific | 2023 |
| Cfcw Ltd | Wholesale & retail | 2024 |
| CGX Global Ltd | Financial services | 2023 |
| CGX Holdings (Global) Ltd | Financial services | 2023 |
| Chainedev Limited | Information & communication | 2023 |
| Champions Sports Academy Limited | Arts & recreation | 2012 |
| Charles Rutherford Crane Services Limited | Professional & scientific | 2024 |
| Charm Property Management Ltd | Real estate | 2014 |
| CHM Motors Ltd | Wholesale & retail | 2017 |
| CIP Network Ltd | Extraterritorial | 2015 |
| CIT (N.I.) Ltd | Hospitality | 2024 |
| CJ Paving Contracts Ltd | Construction | 2022 |
| CJA (N.I.) Ltd | Manufacturing | 2021 |
| CJM Groundworks Limited | Construction | 2018 |
| CJT Construction Limited | Construction | 2018 |
| Clanferran Limited | Financial services | 2024 |
| Clarke Homes and Developments Limited | Construction | 2020 |
| Cleared Ground Limited | Professional & scientific | 2022 |
| Clearer Group Limited | Manufacturing | 2021 |
| Cliad Services Ltd | Hospitality | 2018 |
| Clms Elite Property Investment Ltd | Real estate | 2023 |
| Closeburn Developments Limited | Construction | 2016 |
| CM Developments (N.I.) Ltd | Construction | 2023 |
| Cmcc Vehicle Solutions Ltd | Manufacturing | 2024 |
| CMK1 Ltd | Administrative & support | 2025 |
| CMS Building and Electrical Services Ltd | Construction | 2019 |
| CNG Sports Group Ltd | Arts & recreation | 2026 |
| Coast Media Limited | Professional & scientific | 2022 |