| Ballyskeagh Estates Limited | Real estate | 1976 |
| Ballyurnanellan Properties Limited | Professional & scientific | 2005 |
| Ballywalter Youth and Community Co-Operative | Health & social care | 2000 |
| Bambam Properties Limited | Real estate | 2006 |
| Bangel (N.I.) Limited | Real estate | 2020 |
| Bangor Auctions Ltd | Wholesale & retail | 2024 |
| Bann Carraig Limited | Construction | 2011 |
| Banyan Brands PTE Ltd | Wholesale & retail | 2025 |
| Barn Animal Rescue | Other services | 2020 |
| Barnside Properties Limited | Construction | 2019 |
| Barnwell Farm Cottages Limited | Hospitality | 2007 |
| Baron Fish Sales Ltd | Wholesale & retail | 2023 |
| Barrs Bay Ltd | Manufacturing | 2021 |
| Baths R US Limited | Wholesale & retail | 2020 |
| Battletown Renewable Energy Ltd | Financial services | 2021 |
| Bawpany Director Limited | Wholesale & retail | 2025 |
| Bayaju ZNG Limited | Wholesale & retail | 2023 |
| BBR Restaurants Ltd | Hospitality | 2025 |
| BC Asset Finance Ltd | Financial services | 2007 |
| BDS Freight Limited | Transport & logistics | 2018 |
| BDV Property Ltd | Real estate | 2026 |
| BE Your Authentic Self Ltd | Health & social care | 2024 |
| BEE Fitter Limited | Arts & recreation | 2025 |
| Beechgrove Renewables Limited | Energy | 2013 |
| Beechwood Nurseries Limited | Wholesale & retail | 2013 |
| Beeps Eats Ltd | Wholesale & retail | 2025 |
| Beeps Shakes & Treats Ards Ltd | Manufacturing | 2026 |
| Beers Engineering Consultancy Limited | Professional & scientific | 1997 |
| Behaviour Help ABA Services International Limited | Education | 2021 |
| Belfast Cremation Services Limited | Other services | 2022 |
| Belfast Developments Ltd | Real estate | 2026 |
| Belfast Limited | Professional & scientific | 2016 |
| Belfast School of Salsa Limited | Arts & recreation | 2025 |
| Belfast Shoulder Clinic Ltd | Health & social care | 2018 |
| Belgravia House Property Management Company Limited | Households | 2006 |
| Belmont Furnishings Limited | Wholesale & retail | 2006 |
| Beltraine Developments Limited | Construction | 2003 |
| Belvedere Estate Management Limited | Households | 1995 |
| Benny Crawford & SON Ltd | Wholesale & retail | 2015 |
| Berkstone Limited | Real estate | 2024 |
| Bernard Mckee Ltd | Wholesale & retail | 2025 |
| Berobe Ltd | Construction | 2014 |
| Berts Builders Ltd | Professional & scientific | 2020 |
| Bespoke Bathrooms North Down Ltd | Construction | 2024 |
| Bespoke Staging Ltd | Professional & scientific | 2026 |
| Best Restaurants Limited | Extraterritorial | 2011 |
| Bestcarsni Ltd | Wholesale & retail | 2025 |
| Beswick Medicolegal Limited | Health & social care | 2025 |
| BG Stores Limited | Wholesale & retail | 2011 |
| BGA Architects Ltd | Professional & scientific | 2006 |
| BGA Expert Witness Services Limited | Professional & scientific | 2019 |
| BGL Enterprises Limited | Wholesale & retail | 2017 |
| Big Hits Radio UK Ltd | Information & communication | 2017 |
| Big Idea Digital Ltd | Information & communication | 2017 |
| Big T (N.I.) Ltd | Information & communication | 2021 |
| Bigfoot Construction Limited | Construction | 2012 |
| Bigfoot Technologies Limited | Wholesale & retail | 2025 |
| Bighitsradio.Uk/Ardsradio.Uk.Ltd Ltd. | Information & communication | 2025 |
| Bilal CAL Limited | Wholesale & retail | 2025 |
| Billington Energy & Electrical Ltd | Construction | 2023 |
| Billunion Limited | Wholesale & retail | 2025 |
| Bingham Technical Services Ltd | Construction | 2025 |
| BIO Cranial Osteopathy Limited | Health & social care | 2015 |
| BIO TAG Ltd | Professional & scientific | 2025 |
| Bioguard Environmental Limited | Professional & scientific | 2005 |
| Biyertop Ltd | Wholesale & retail | 2025 |
| BK Event Management Limited | Hospitality | 2025 |
| BK OH Services Ltd | Health & social care | 2023 |
| Black Modern Media Productions Ltd | Manufacturing | 2022 |
| Blackstaff BPM Limited | Households | 2024 |
| Blackstaff Builders Limited | Construction | 2012 |
| Blackstaff Limited | Construction | 2018 |
| Blackthorn Ireland Ltd | Extraterritorial | 2007 |
| Blackward Greer Properties Ltd | Real estate | 2024 |
| Blackwater Graphics Ltd | Information & communication | 2018 |
| Blakely Contracts Ltd | Construction | 2015 |
| Blazin Logs Ltd | Wholesale & retail | 2022 |
| Bleacher Limited | Wholesale & retail | 2025 |
| Blessed Clean Homes Limited | Administrative & support | 2026 |
| Bling Flash Limited | Wholesale & retail | 2023 |
| Bloomfield Developments Belfast Limited | Construction | 2024 |
| Bloomfield Research Group Ltd | Information & communication | 2022 |
| BLR Sports Ltd | Education | 2025 |
| BLT Investments LLP | | 2012 |
| Blue Build Energy Ltd | Professional & scientific | 2011 |
| Blue Build Insulation Ltd | Professional & scientific | 2011 |
| Blue Carpeet Limited | Wholesale & retail | 2025 |
| Blue Estates Developments Ltd | Real estate | 2013 |
| Blue Monkee Digital Limited | Information & communication | 2015 |
| Blue Note Advisors Limited | Financial services | 2025 |
| Blue Ptarmigan Ltd | Wholesale & retail | 2023 |
| Blueberry Heights Ltd | Wholesale & retail | 2024 |
| Bluebuild (NI) Ltd | Professional & scientific | 2014 |
| Bluebuild Bangor Ltd | Construction | 2018 |
| Blunderbuss Limited | Wholesale & retail | 2025 |
| Blunt Limited | Wholesale & retail | 2025 |
| BMP Products Limited | Manufacturing | 2024 |
| Bodice Limited | Wholesale & retail | 2025 |
| BOG Standard Products Ltd | Manufacturing | 2000 |
| Bogie Limited | Wholesale & retail | 2025 |