| Blackwell Earthmoving Limited | Construction | 2020 |
| Blackwells Hospitality Ltd | Hospitality | 2025 |
| Blackwells of Herons Farm Limited | Agriculture & fishing | 2003 |
| Blak Transport Limited | Transport & logistics | 2014 |
| Blake FAB Engineering Ltd | Manufacturing | 2012 |
| Blake Hill Consulting Services Ltd | Other services | 2020 |
| Blanchette Building Heating & Plumbing Limited | Construction | 2024 |
| Bland Landscapes Limited | Administrative & support | 2002 |
| Blank Space Limited | Information & communication | 2019 |
| Blaze Consultancy Limited | Information & communication | 2011 |
| BLD Couriers Ltd | Transport & logistics | 2022 |
| BLD Roofing Solutions Ltd | Construction | 2025 |
| Bleandale Management Company Limited | Households | 1980 |
| Bleck Business Limited | Other services | 2021 |
| Bleckgrove Limited | Households | 1982 |
| Blinc Brands Limited | Wholesale & retail | 2025 |
| Blis International Limited | Financial services | 2016 |
| Bliss Pet Limited | Transport & logistics | 2008 |
| Blizzco Developers Limited | Construction | 2012 |
| BLM in the Stix | Education | 2020 |
| BLM Property Limited | Real estate | 2021 |
| Blmcontractors Limited | Construction | 2015 |
| BLN Scaffolding Limited | Construction | 2016 |
| Bloc Consulting Ltd | Professional & scientific | 2014 |
| Block by Block Property Ltd | Real estate | 2022 |
| Block Managers Limited | Real estate | 2011 |
| Blois Plumbing and Heating Ltd. | Construction | 2012 |
| Blonay Limited | Information & communication | 2002 |
| Blood Orange Pictures Ltd | Information & communication | 2024 |
| Bloom Life Care Ltd | Professional & scientific | 2025 |
| Bloomed in Wild Ltd | Wholesale & retail | 2025 |
| Bloomfield Consultants Limited | Professional & scientific | 2018 |
| Bloomfield Furniture Limited | Wholesale & retail | 2002 |
| Bloomsbury Mews (1) Management Company Limited | Households | 2005 |
| Blossom Brands Limited | Professional & scientific | 2025 |
| Blossom Living Limited | Health & social care | 2018 |
| Blossom Within & Beyond Psychological & Therapeutic Services Limited | Public administration | 2025 |
| Blowers Homes Ltd | Construction | 2013 |
| Blue & Ginger LLP | | 2005 |
| Blue Barn Management Company Limited | Professional & scientific | 2011 |
| Blue BOY Limited | Agriculture & fishing | 2002 |
| Blue Bridge Associates Limited | Professional & scientific | 2018 |
| Blue Brique Ltd | Real estate | 2022 |
| Blue Coast Wealth Management Limited | Financial services | 2016 |
| Blue DOT Property Development Ltd | Real estate | 2019 |
| Blue FOX Cleaning Services Ltd | Administrative & support | 2025 |
| Blue Journey Ltd | Other services | 2019 |
| Blue Note Advisory Limited | Financial services | 2018 |
| Blue Orchid Consultancy Ltd | Real estate | 2022 |
| Blue Poppy Holdings Limited | Real estate | 2024 |
| Blue Poppy Property Management Services Ltd | Real estate | 2024 |
| Blue Sky Service 21 Limited | Health & social care | 2021 |
| Blue Springs Agency Ltd. | Administrative & support | 2012 |
| Blue Springs Care Limited | Health & social care | 2025 |
| Blue Springs Security Services Ltd. | Administrative & support | 2017 |
| Blue Square Financial Limited | Financial services | 2017 |
| Blue Star Aerial Systems Ltd | Construction | 2006 |
| Blue Strawberry Restaurants Limited | Hospitality | 2002 |
| Blue Tiger Consultants Ltd | Information & communication | 2011 |
| Blue Tiger Logistics Ltd | Transport & logistics | 2024 |
| Blue Topard Ltd | Real estate | 2018 |
| Blue Wave Exterior Cleaning Limited | Administrative & support | 2024 |
| Blue's Kitchen and Catering Limited | Wholesale & retail | 2020 |
| BLUE4 Behaviour Limited | Extraterritorial | 2012 |
| BLUE4 Culture Limited | Extraterritorial | 2012 |
| BLUE4 International Limited | Professional & scientific | 2023 |
| BLUE4 Limited | Professional & scientific | 2024 |
| BLUE4 Performance Limited | Extraterritorial | 2015 |
| BLUEBOX7000 Limited | Financial services | 2007 |
| Blueboys Coaching Limited | Arts & recreation | 2014 |
| Bluecakes Productions Limited | Arts & recreation | 2007 |
| Bluecap Studios Ltd | Information & communication | 2026 |
| Bluegates Place Managment Company Limited | Households | 2015 |
| Bluelight Global Solutions Ltd | Administrative & support | 2010 |
| Blueocean Global Products Ltd | Wholesale & retail | 2014 |
| Blueprint Facilities Management Ltd | Administrative & support | 2025 |
| Bluesky Equity Management Limited | Financial services | 2017 |
| Bluetooth Autos Ltd | Wholesale & retail | 2024 |
| Bluewood Building Services Ltd | Construction | 2026 |
| Blume Technologies Limited | Information & communication | 2021 |
| Blyra Construction Services Limited | Professional & scientific | 2018 |
| Blyth Bros Builders Limited | Construction | 2024 |
| Blyth Investment Holdings Limited | Real estate | 1996 |
| Blytholme Estates Limited | Construction | 2020 |
| Blytholme Group Limited | Financial services | 2020 |
| Blytholme Services Limited | Professional & scientific | 2020 |
| BM Hotel Management Services Ltd | Hospitality | 2022 |
| BM Mini Tech Ltd | Wholesale & retail | 2020 |
| BM Smart Solutions Ltd | Wholesale & retail | 2025 |
| Bmac Associates Ltd | Information & communication | 2025 |
| BMB Properties Limited | Financial services | 2020 |
| BMG Steel Limited | Construction | 2024 |
| Bmjc Limited | Extraterritorial | 2024 |
| BMM Bodywork & Spray Painting Ltd | Manufacturing | 2018 |
| BMP Groundworks Limited | Construction | 2025 |
| BMS Electrical Training CIC | Construction | 2020 |
| BMS Training Limited | Construction | 2026 |
| Board Loaders Ltd | Construction | 2026 |
| Boathouse Residents Association Limited | Real estate | 2002 |
| Boatwright Services Limited | Manufacturing | 2012 |