| Bhavesh Patel Limited | Construction | 2019 |
| Bhinder Brother Constructions Ltd | Construction | 2022 |
| Bhinder Construction Ltd | Construction | 2021 |
| Bhinder Courier Services Limited | Transport & logistics | 2026 |
| Bhogal DIY Limited | Construction | 2024 |
| BHX Travel Limited | Transport & logistics | 2013 |
| BIC U.K. Limited | Wholesale & retail | 1944 |
| Bick Green Associates Limited | Administrative & support | 2020 |
| Bickenstaff & Knowles Limited | Wholesale & retail | 1981 |
| Bickerton's Aerodromes Limited | Transport & logistics | 1938 |
| BID Buy Build Ltd | Real estate | 2026 |
| Big Beat Games Ltd | Information & communication | 2024 |
| Big Bridge Portal Limited | Wholesale & retail | 2023 |
| Big Buddha (UK) Ltd | Wholesale & retail | 2019 |
| Big GEE Media Services Ltd | Wholesale & retail | 2021 |
| Big Joes Seafood Limited | Hospitality | 2019 |
| Big Ladder Ltd | Information & communication | 2025 |
| Big Painters Ltd | Construction | 2020 |
| Big Red House Services Limited | Professional & scientific | 2020 |
| Big Sofa Technologies Limited | Information & communication | 2013 |
| Biggerimpex Ltd | Wholesale & retail | 2025 |
| Bigpush Couriers Ltd | Transport & logistics | 2023 |
| Bigshots Golf (Europe) Limited | Arts & recreation | 2018 |
| Bigshots Golf International Limited | Arts & recreation | 2016 |
| Bihaan Limited | Wholesale & retail | 2025 |
| Biizbook Ltd | Information & communication | 2020 |
| Bikan Investments Limited | Hospitality | 2007 |
| Bikewise Limited | Extraterritorial | 2013 |
| Bilal Gohar Ltd | Wholesale & retail | 2024 |
| Bilko Ltd | Wholesale & retail | 2021 |
| Bill the Baker Limited | Hospitality | 2017 |
| Billboard Costa Ltd | Manufacturing | 2024 |
| Billings Management Limited | Real estate | 1993 |
| BIN Marra Falcons Limited | Agriculture & fishing | 2026 |
| Bindi(G.B.)Limited | Professional & scientific | 2000 |
| Bindra & Sons Limited | Wholesale & retail | 2024 |
| Bing & Co. Consulting Ltd | Information & communication | 2025 |
| Binishaz Services Ltd. | Real estate | 2019 |
| BIO Cleaners Limited | Transport & logistics | 2016 |
| Bioaesthetics Studio Ltd | Other services | 2025 |
| Biological Recording Company Ltd | Education | 2023 |
| Biopolis Lifesciences Private Limited | Extraterritorial | 2018 |
| Birdy Luxury Designs Limited | Wholesale & retail | 2015 |
| Birklean Detailing Ltd | Wholesale & retail | 2018 |
| Birma Ltd | Transport & logistics | 2025 |
| Birse Assets Limited | Real estate | 2026 |
| Bishop Media Group Ltd | Information & communication | 2024 |
| Bishop Strategy Group Ltd | Professional & scientific | 2026 |
| Bishwa and SON Ltd | Real estate | 2025 |
| Bismi Online Ltd | Wholesale & retail | 2025 |
| Bite Group (West END) Limited | Hospitality | 2026 |
| Bite Restaurant (West END) Limited | Hospitality | 2026 |
| Bitlynx Limited | Information & communication | 2025 |
| Bitpos Limited | Information & communication | 2022 |
| Bits Bazzr Ltd | Wholesale & retail | 2025 |
| BIZ Associates Ltd | Information & communication | 2013 |
| BIZ Boost Ltd | Information & communication | 2011 |
| Biznest Ltd | Wholesale & retail | 2016 |
| Bizzybills Ltd | Information & communication | 2025 |
| BJ Fitters Ltd | Construction | 2013 |
| BJG Enterprises Ltd | Professional & scientific | 2011 |
| Bjpropers Ltd | Construction | 2019 |
| BJS Estates Ltd | Real estate | 2024 |
| BK Superstores Ltd | Wholesale & retail | 2017 |
| BL Bottling Holdings UK Limited | Financial services | 2016 |
| Black Diamondz Limited | Arts & recreation | 2012 |
| Black Jewel Investments Ltd | Real estate | 2024 |
| Black Oak Meats Ltd | Wholesale & retail | 2026 |
| Black Star HR Limited | Professional & scientific | 2025 |
| Black Star Media Group Ltd | Professional & scientific | 2020 |
| Black&Blanco Solutions Ltd | Professional & scientific | 2021 |
| Blackborn Limited | Professional & scientific | 1996 |
| Blackfeather Ltd | Wholesale & retail | 2017 |
| Blackstone Merchandise Limited | Wholesale & retail | 2020 |
| Blackstone Sports Management Limited | Education | 2020 |
| Blackstone Telecommunications Associates Limited | Professional & scientific | 2021 |
| Blackwater Capital Ltd | Wholesale & retail | 2023 |
| Blade Barber Shop Limited | Other services | 2025 |
| Blandford House (UK) Limited | Health & social care | 2015 |
| Blenheim Court (Firstgate) RTM Company Limited | Households | 2023 |
| BLESSED7 Limited | Health & social care | 2014 |
| Blessway Companion Limited | Other services | 2026 |
| Bletchley Flats Limited | Real estate | 2020 |
| BLH Brands Limited | Other services | 2019 |
| Bling Box London Limited | Wholesale & retail | 2024 |
| Blinging Drops Limited | Wholesale & retail | 2025 |
| Blink and Bloom Beauty Ltd | Other services | 2025 |
| Blissleaf Ltd | Manufacturing | 2024 |
| BLJ Creations Ltd | Wholesale & retail | 2012 |
| Blockacre Residents Management Limited | Real estate | 1987 |
| Bloom Cosmetic Group Ltd | Other services | 2021 |
| Blooms EN Vogue Ltd | Arts & recreation | 2019 |
| Blossom Way Property Limited | Real estate | 2014 |
| Blowers Vape Shop Ltd | Wholesale & retail | 2019 |
| BLS Burnells LLP | | 2016 |
| BLU Cherry Limited | Wholesale & retail | 2016 |
| Blue Arden Homes Ltd | Real estate | 2021 |
| Blue Arrow Homecare Limited | Health & social care | 2022 |
| Blue Cosmetics Ltd | Other services | 2015 |
| Blue Cube Limited | Manufacturing | 1998 |