| Breffni House Limited | Health & social care | 2005 |
| Breffni Limited | Health & social care | 2020 |
| Breffni Lodge Limited | Health & social care | 2003 |
| Bremar Training C.I.C. | Education | 2020 |
| Brenda LEE Ltd | Wholesale & retail | 2025 |
| Brendan Alexis Deery Ltd | Wholesale & retail | 2022 |
| Brendan Boyd Ltd | Wholesale & retail | 2024 |
| Brendan O Hare Electrical Ltd | Construction | 2024 |
| Brennan Facilities Management Limited | Professional & scientific | 1988 |
| Brennans Irish Linens Ltd | Manufacturing | 2024 |
| Brent Lodge Residents Management Ltd | Households | 2019 |
| Brentnall Legal Limited | Professional & scientific | 2018 |
| Bresin Limited | Health & social care | 2022 |
| Breslin Consulting Ltd | Professional & scientific | 2023 |
| Breton Hall Area (Lisburn) Management Company Limited | Households | 2009 |
| Brew & Batch Ltd | Hospitality | 2025 |
| Brew and Bake Cafe Ltd | Hospitality | 2018 |
| Brew Bars Holdings Limited | Hospitality | 2025 |
| Brewed Bunny Ltd | Wholesale & retail | 2019 |
| Brewery Restaurants Limited | Hospitality | 2014 |
| Brewis Property Ltd | Real estate | 2026 |
| Brewmore Meadows Ltd | Hospitality | 2021 |
| Brhu Limited | Real estate | 2026 |
| BRI Wind Farms 4 Limited | Energy | 2016 |
| BRI Wind Farms 6 Limited | Energy | 2018 |
| Brian Alton Dental Care Limited | Health & social care | 2010 |
| Brian Farley Ltd | Wholesale & retail | 2025 |
| Brian Grant Haulage Limited | Transport & logistics | 2015 |
| Brian Henry Limited | Wholesale & retail | 2025 |
| Brian Holmes Painting Ltd | Administrative & support | 2018 |
| Brian Inns Ltd | Hospitality | 2019 |
| Brian Kelly Solicitors Limited | Professional & scientific | 2021 |
| Brian Keown Ltd | Wholesale & retail | 2025 |
| Brian LEE Ltd | Wholesale & retail | 2025 |
| Brian Lyttle Ltd | Wholesale & retail | 2025 |
| Brian Mccance (Steel) Limited | Manufacturing | 1976 |
| Brian Mccrum Ltd | Health & social care | 2018 |
| Brian Meneely Limited | Real estate | 1961 |
| Brian Savage Ltd | Wholesale & retail | 2025 |
| Brian Sheridan Ltd | Wholesale & retail | 2022 |
| Brian W Murray Limited | Professional & scientific | 1999 |
| Brian's Butchers Ltd | Wholesale & retail | 2025 |
| Briarfield Lettings Ltd | Real estate | 2026 |
| Briarfield Management Company Limited | Households | 2025 |
| Brick ROW Ltd | Information & communication | 2012 |
| Brickcourt Property NI Limited | Real estate | 2013 |
| Brickkiln Waste Limited | Water & waste | 2000 |
| Bricklayers Online Ltd | Construction | 2023 |
| BRICKS4KIDZ N.I. Limited | Education | 2025 |
| Bridge Belfast Ltd | Health & social care | 2024 |
| Bridge CA Limited | Professional & scientific | 2016 |
| Bridge Commercials Limited | Wholesale & retail | 1995 |
| Bridge Developments (N.I.) Ltd | Construction | 2021 |
| Bridge Fuels Ltd | Wholesale & retail | 2025 |
| Bridge House Management Company (NI) Limited | Extraterritorial | 2008 |
| Bridge Park Developments Limited | Real estate | 1999 |
| Bridge SS Ltd | Wholesale & retail | 2016 |
| Bridge Street (Kilkeel) Apartments Management Company Limited | Extraterritorial | 2001 |
| Bridgepoint Transport & Distribution Ltd | Transport & logistics | 2026 |
| Bridgeroad L.P. | | 2017 |
| Bridgestone Property Limited | Real estate | 2024 |
| Bridgewater Auditing & Accounting Limited | Professional & scientific | 2003 |
| Bridgewood Agencies Limited | Professional & scientific | 1979 |
| Bridgewood Properties Limited | Real estate | 1999 |
| Bridle Limited | Wholesale & retail | 2025 |
| Brief Design Ltd | Professional & scientific | 2023 |
| Briefed Limited | Information & communication | 2011 |
| Bright Light Consultancy Limited | Information & communication | 2022 |
| Bright Sky Facilities Management Limited | Real estate | 2010 |
| Bright Umbrella Drama Company Limited | Arts & recreation | 2020 |
| Brightcore 2026 Ltd | Wholesale & retail | 2026 |
| Brighter Gardens Ltd | Administrative & support | 2016 |
| Brighton Brickworks Ltd | Construction | 2020 |
| Brights Investments Limited | Real estate | 2015 |
| Brightwater Financial (NI) Ltd | Financial services | 2010 |
| Brightwave Trading Limited | Wholesale & retail | 2026 |
| Brighzeng Limited | Wholesale & retail | 2025 |
| Brigstock Campsite Limited | Construction | 2017 |
| Brikie Properties Ltd | Financial services | 2017 |
| Brilliant Balls Limited | Arts & recreation | 2021 |
| Brilliant Buttons (N.I.) Ltd | Information & communication | 2018 |
| Brink! Stories C.I.C. | Professional & scientific | 2023 |
| Brink! Think Limited | Professional & scientific | 2023 |
| Brinmaks Project LP | | 2017 |
| Brintsword Project LP | | 2017 |
| Brio Advisory Limited | Professional & scientific | 2020 |
| Brio Group Ltd | Professional & scientific | 2013 |
| Brio Properties Limited | Financial services | 2021 |
| Brio Services Limited | Professional & scientific | 2020 |
| Brioearth Ltd | Wholesale & retail | 2025 |
| Brisk Green Energy International Limited | Professional & scientific | 2022 |
| Brispa Leisure Ltd | Hospitality | 2005 |
| Bristoden Ltd | Real estate | 2022 |
| Bristol Ramparts LP | | 2016 |
| Britannia Towers II Limited | Information & communication | 2014 |
| British Finance Company Limited | Extraterritorial | 1926 |
| Britonix Limited | Wholesale & retail | 2023 |
| Britova Solutions Limited | Wholesale & retail | 2025 |
| BRL Boucher Ltd | Hospitality | 2024 |
| BRL Properties Antrim Ltd | Real estate | 2024 |