| Bimsco Ltd | Construction | 2018 |
| Binarii Labs (UK) Ltd | Information & communication | 2024 |
| Binary Meadow Ltd | Information & communication | 2026 |
| Binbin Limited | Administrative & support | 2008 |
| Binder Construction Limited | Construction | 2024 |
| Binnaz by Behzat Limited | Wholesale & retail | 2014 |
| Binning Concrete Limited | Administrative & support | 2020 |
| Binning Investments Ltd | Real estate | 2020 |
| Binshow Ltd | Construction | 2024 |
| Binsols Technologies Ltd | Wholesale & retail | 2025 |
| BIO Active Supported Living Ltd | Administrative & support | 2019 |
| BIO Beauty and Nails Limited | Other services | 2025 |
| BIO Digital Care Ltd | Professional & scientific | 2021 |
| BIO Sonic Productions Ltd | Information & communication | 2023 |
| Biobrick Technology & Solutions Ltd | Financial services | 2026 |
| Biocrocks UK Ltd | Wholesale & retail | 2026 |
| Biomed Consulting Ltd | Professional & scientific | 2018 |
| Biopath Ltd | Professional & scientific | 2025 |
| Biopulse Limited | Professional & scientific | 2024 |
| Bioq Pharma Limited | Extraterritorial | 2005 |
| Biorganic Limited | Wholesale & retail | 1998 |
| Biosash Ltd | Wholesale & retail | 2022 |
| Biotech Consultants Ltd | Professional & scientific | 2012 |
| Bioway Limited | Professional & scientific | 2024 |
| BIP Global Ltd | Administrative & support | 2018 |
| BIR Construct Ltd | Construction | 2019 |
| BIR Investments Ltd | Real estate | 2017 |
| BIR Payroll Ltd | Administrative & support | 2015 |
| Birch Medical Ltd. | Health & social care | 2015 |
| Birches London Ltd | Wholesale & retail | 2026 |
| Bircsinvestment Consultants Limited | Professional & scientific | 2024 |
| Bird EYE Security Forces Ltd | Administrative & support | 2022 |
| Birdi Building Services Ltd | Real estate | 2022 |
| Birdview Investments Limited | Financial services | 2026 |
| Birdwood Veleting Centre Limited | Other services | 2025 |
| Birladamy Services Limited | Construction | 2016 |
| Birmingham Circumcision Centre Limited | Health & social care | 2022 |
| Biryani Pointe Limited | Hospitality | 2023 |
| BIS HAN Developments Ltd | Construction | 2017 |
| Bisa Overseas Ltd | Professional & scientific | 2024 |
| Biscayne Developments Limited | Real estate | 2026 |
| Bishop Roofing Limited | Wholesale & retail | 2005 |
| Bishops AI Strategy Ltd | Professional & scientific | 2026 |
| Bishops Avenue Investments Limited | Real estate | 2020 |
| Bishops Online Tutoring Ltd | Education | 2025 |
| Bishops Street Investment Ltd | Real estate | 2015 |
| Bisla Builder Ltd | Construction | 2024 |
| Bismillah (London) Fast Foods Ltd | Hospitality | 2021 |
| Bismillah Umrah Tours Ltd | Administrative & support | 2025 |
| BIT Specialist Ltd | Information & communication | 2013 |
| Bitaly Ltd | Wholesale & retail | 2020 |
| Bitbros Limited | Information & communication | 2023 |
| Bitebliss Burger Ltd | Hospitality | 2024 |
| Bits and Bargains Ltd | Wholesale & retail | 2025 |
| Biwa Developments Limited | Real estate | 2022 |
| Biwa Jewelleries Limited | Wholesale & retail | 2023 |
| Biwad Group Ltd | Administrative & support | 2020 |
| Biwad Holdings Limited | Professional & scientific | 2020 |
| Biwad Ltd | Professional & scientific | 2020 |
| Biwad Services Ltd | Administrative & support | 2026 |
| BIZ Energies Limited | Administrative & support | 2014 |
| Bizan Consultancy Limited | Wholesale & retail | 2020 |
| Bizease Solutions Limited | Wholesale & retail | 2026 |
| Bizhood Ltd | Wholesale & retail | 2025 |
| Bizmax Global Consultants Ltd | Professional & scientific | 2020 |
| Bizness Training Limited | Education | 2014 |
| Bizserve UK Ltd | Other services | 2009 |
| Bizspot Ltd | Information & communication | 2025 |
| Biztech Consultants Limited | Information & communication | 2010 |
| Bizz Interactive Services Limited | Wholesale & retail | 2025 |
| Bizz Properties Ltd | Real estate | 2020 |
| BJD Resources (UK) Ltd | Health & social care | 2023 |
| BJR Motors & Cafe Limited | Wholesale & retail | 2025 |
| BJS Fashion Ltd | Wholesale & retail | 2013 |
| BJS International Limited | Administrative & support | 2021 |
| BJS Projects Limited | Administrative & support | 2021 |
| BK Casting Agency Limited | Administrative & support | 2021 |
| BK Custom Merch Ltd | Manufacturing | 2026 |
| BK Ilford Limited | Hospitality | 2025 |
| BK Real Estate Group Ltd | Real estate | 2024 |
| BK Start Limited | Professional & scientific | 2024 |
| BKB Collections Ltd | Wholesale & retail | 2025 |
| BKH Autos Ltd | Wholesale & retail | 2024 |
| BKM Care Limited | Health & social care | 2025 |
| BKP Properties Limited | Real estate | 2020 |
| BKS Estate Ltd | Real estate | 2025 |
| Black & White Accountants Ltd. | Professional & scientific | 2017 |
| Black and White Web Designs Ltd | Information & communication | 2019 |
| Black Bishop Limited | Real estate | 2017 |
| Black Bishop Properties Limited | Real estate | 2020 |
| Black Box (London) Limited | Manufacturing | 2014 |
| Black Brick Estates Ltd | Real estate | 2026 |
| Black Cube Property Investment Ltd | Real estate | 2020 |
| Black Daimond Limited | Construction | 2020 |
| Black Diamond Gym Ltd | Arts & recreation | 2021 |
| Black Diamond Gym UK Community Interest Company | Arts & recreation | 2026 |
| Black Gold Publishing Ltd | Information & communication | 2020 |
| Black Haven Group Limited | Wholesale & retail | 2025 |
| Black Horse Assets Ltd | Real estate | 2019 |
| Black Horse Dwellings Ltd | Construction | 2019 |