| Business Exhibitions (NI) Limited | Professional & scientific | 1991 |
| Business Finance & Capital (LS1) Limited | Financial services | 2019 |
| Business First Associates Ltd | Administrative & support | 2020 |
| Business First Network Ltd | Administrative & support | 2014 |
| Business First Sales Ltd | Extraterritorial | 2022 |
| Business Goose Ltd | Hospitality | 2023 |
| Business Improvement Solutions (IRL) Limited | Professional & scientific | 2006 |
| Business Intelligence Plus Limited | Information & communication | 2023 |
| Business Protection Advisory Ltd Ltd | Financial services | 2023 |
| Business Publication Company (N.I.) Limited | | 2004 |
| Business Rethink Ltd | Professional & scientific | 2007 |
| Business Simulations Ltd | Professional & scientific | 2014 |
| Business Storage Products Limited | Wholesale & retail | 2009 |
| Business Supply Company Ltd-The | Wholesale & retail | 1996 |
| Business Tourism Services Limited | Administrative & support | 2017 |
| Business Union Credit Limited | Administrative & support | 2017 |
| Buslink Belfast Ltd | Transport & logistics | 2025 |
| Bussywom Ltd | Wholesale & retail | 2026 |
| Busybee Cuppa Ltd | Hospitality | 2025 |
| Butcher's Pet Care NI Ltd | Administrative & support | 2021 |
| Butler Stream Limited | Financial services | 2022 |
| Buttercup Holdings Ltd | Real estate | 2021 |
| Buttercup's OUT of School Care Limited | Health & social care | 2008 |
| Buy & Sell Northern Ireland Limited | | 1995 |
| Buy Buddy Ltd | Wholesale & retail | 2026 |
| Buzz Giveaways Ltd | Arts & recreation | 2026 |
| Buzzards Hill Kitchen Ltd | Hospitality | 2025 |
| BW Ireland Ltd | Wholesale & retail | 2024 |
| Bwangliamo Limited | Wholesale & retail | 2023 |
| Bwfni Ltd | Administrative & support | 2025 |
| Bwyg 81 Ltd | Hospitality | 2019 |
| Bxuo Kiox Ltd | Wholesale & retail | 2024 |
| BY Detail Limited | Manufacturing | 2026 |
| BY EL Ephandi Limited | Hospitality | 2023 |
| BY the Doctor Ltd | Health & social care | 2024 |
| Byce Catering Limited | Hospitality | 2025 |
| Bynd Dgtl Ltd | Professional & scientific | 2021 |
| Byran Ltd | Education | 2018 |
| Byron Halt Management Company Limited | Real estate | 2023 |
| Byron Projects Limited | Construction | 2014 |
| Byset Limited | Real estate | 1998 |
| Bytezen Limited | Wholesale & retail | 2024 |
| Bywater Capital (Winetavern) Limited | Real estate | 2015 |
| Byzerica Limited | Wholesale & retail | 2025 |
| Béal Feirste Limited | Real estate | 2025 |
| C & a | | 1959 |
| C & a Davidson Associates (N.I.) Ltd | Professional & scientific | 2016 |
| C & B Properties (NI) Limited | Real estate | 2010 |
| C & E Ventilation Limited | Construction | 2017 |
| C & G Developments Limited | Construction | 2001 |
| C & G Rentals Ltd | Real estate | 2022 |
| C & H Farm Holdings Ltd | Financial services | 2023 |
| C & I Landscapes Services Limited | Administrative & support | 2021 |
| C & K Gibson Limited | Health & social care | 2013 |
| C & M Retail Ltd | Information & communication | 2006 |
| C & N Rooney Limited | Health & social care | 2007 |
| C & S Group Ltd | Hospitality | 2023 |
| C & T Retail Ltd | Wholesale & retail | 2007 |
| C and D Works Limited | Real estate | 2025 |
| C Christie Consulting Ltd | Professional & scientific | 2024 |
| C D Diamond & Co Ltd | Professional & scientific | 2017 |
| C D Fairfield Capital Limited | Professional & scientific | 2011 |
| C E United Ltd | Hospitality | 2016 |
| C E Vend Ltd | Professional & scientific | 2011 |
| C F P Business Solutions Limited | Information & communication | 1996 |
| C Frampton Ltd | Other services | 2003 |
| C G C Laboratory Ltd | Professional & scientific | 2004 |
| C J L Ltd | Administrative & support | 2005 |
| C J Mccoy Building Limited | Construction | 2025 |
| C J Stewart & SON Limited | Wholesale & retail | 1941 |
| C J Transportation Ltd | Transport & logistics | 2026 |
| C Kelly Ltd | Professional & scientific | 2026 |
| C Maxwell Transport Ltd | Transport & logistics | 2019 |
| C MR C Accident Solutions Ltd | Administrative & support | 2026 |
| C O Developments Limited | Real estate | 2007 |
| C Realisations 2023 Limited | Wholesale & retail | 1999 |
| C Rodgers Decorators Ltd | Other services | 2025 |
| C S Business Ltd | Administrative & support | 1994 |
| C&A Country Foods Ltd | Manufacturing | 2024 |
| C&C Apartments Ltd | Real estate | 2025 |
| C&C Business Lettings Limited | Real estate | 2025 |
| C&C Capital Group Ltd | Real estate | 2026 |
| C&C Glass Limited | Wholesale & retail | 2015 |
| C&C Locations Ltd | Arts & recreation | 2023 |
| C&Cns Trading Ltd | Transport & logistics | 2023 |
| C&E 24 Limited | Financial services | 2024 |
| C&F Green Energy (UK) Limited | Manufacturing | 2010 |
| C&L Apartments Ltd | Real estate | 2025 |
| C&M Cleaning Services (NI) Ltd | Other services | 2012 |
| C&Mk Property Limited | Real estate | 2018 |
| C&S Executive Travel Ltd | Transport & logistics | 2020 |
| C-Der Productions Ltd | Information & communication | 2022 |
| C-Tec Engineering Holdings Ltd | Financial services | 2021 |
| C.A. Gowdy Limited | Wholesale & retail | 1957 |
| C.A.S. Engineering (NI) Limited | Manufacturing | 2006 |
| C.A.S.Painting Contractors Ltd | Construction | 2020 |
| C.A.Z. Consultancy Ltd | Information & communication | 2023 |
| C.B. Contracts (N.I.) Ltd | Construction | 2000 |
| C.C. Properties Ltd | Real estate | 2018 |
| C.H.A.R.T.E.R. for Northern Ireland | Administrative & support | 2005 |