| Britcross Trade Ltd | Wholesale & retail | 2025 |
| Brite Education Ltd | Administrative & support | 2025 |
| Brithub Guild Ltd | Wholesale & retail | 2025 |
| Britlen Trading Ltd | Wholesale & retail | 2025 |
| Britsilk Wellness Lounge (UK) Limited | Other services | 2025 |
| Britt Asset Management Ltd. | Administrative & support | 2012 |
| Brittech Edge Ltd | Manufacturing | 2025 |
| Brivo ZW Ltd | Wholesale & retail | 2025 |
| Brivon Digital Ltd | Wholesale & retail | 2026 |
| Broadscope Global Ltd | Manufacturing | 2026 |
| Broadstone Accounting Ltd | Professional & scientific | 2018 |
| Brocadero Networks Limited | Information & communication | 2012 |
| Brocco Trade Ltd | Hospitality | 2025 |
| BROCCOLI1 Ltd | Construction | 2025 |
| Brocko Studio Ltd | Information & communication | 2026 |
| Brocksford Consultancy Ltd | Professional & scientific | 2022 |
| Broken Biscuits Limited | Extraterritorial | 2017 |
| Bronzely & Partners LP | | 2019 |
| Brooke Estates Ltd | Real estate | 2026 |
| Brothers of YI Petroleum Limited | Administrative & support | 2014 |
| Brotherton Psychology Ltd | Professional & scientific | 2017 |
| Brow Bar Harrow Ltd | Other services | 2021 |
| Brown Melon Ltd | Information & communication | 2025 |
| Brownlie IP Limited | Professional & scientific | 2026 |
| Brownson Property Ltd | Real estate | 2025 |
| BRP Architecture Ltd | Professional & scientific | 2017 |
| Brtr Ltd | Real estate | 2017 |
| Brunton Healthcare Ltd | Administrative & support | 2025 |
| Bryanstone Residents Association Limited | Households | 1988 |
| Bryn Industrial Co., Ltd | Wholesale & retail | 2026 |
| BSGIKON24 Ltd | Real estate | 2024 |
| BSK Media Ltd | Professional & scientific | 2025 |
| BT Childcare Ltd | Administrative & support | 2020 |
| Buachaille Consulting Ltd | Professional & scientific | 2024 |
| Bubble Bash Ltd | Administrative & support | 2025 |
| Bubutoys Ltd | Wholesale & retail | 2025 |
| Buch Ltd | Arts & recreation | 2013 |
| Buckingham International Culture Ltd | Education | 2022 |
| Buddha Rehab Ltd | Wholesale & retail | 2024 |
| Budge UP Ltd | Information & communication | 2025 |
| Buenezers Limited | Information & communication | 2024 |
| Bufan Electronic Technology Co., Ltd | Wholesale & retail | 2025 |
| Buffalo Housing Association CIC | Hospitality | 2024 |
| Build Like Beavers Ltd | Information & communication | 2020 |
| Build RIG Light Ltd | Arts & recreation | 2025 |
| Building Roles Ltd | Administrative & support | 2025 |
| Bujin Media LLP | | 2020 |
| Bujjen Projects Limited | Professional & scientific | 2016 |
| Buling Betsey Ltd | Wholesale & retail | 2024 |
| Bull and Red Flag Ltd | Arts & recreation | 2026 |
| Bullion-X UK Ltd | Wholesale & retail | 2022 |
| Bulvar.Co Limited | Wholesale & retail | 2026 |
| BUN Apps Ltd | Information & communication | 2025 |
| Bundles of Joy Maternity Project CIC | Public administration | 2025 |
| Bunny Baily Jewelry Co. Ltd | Wholesale & retail | 2025 |
| Buona Vista Consulting Ltd | Professional & scientific | 2025 |
| Bure Valley Property Limited | Real estate | 2025 |
| Burgoynes (Lyonshall) Limited | Agriculture & fishing | 1990 |
| Burgoynes Marquees Limited | Administrative & support | 2014 |
| Burgoynes Pallet Track Limited | Transport & logistics | 2021 |
| Burgreen Ltd | Construction | 2021 |
| Buribu Ltd | Information & communication | 2025 |
| Burlington Opportunities Limited | Construction | 2020 |
| Burncloud Ltd | Information & communication | 2024 |
| Burning Chair Limited | Information & communication | 2018 |
| Burnout Geese Ltd | Health & social care | 2017 |
| Bushfire Ministries International | Other services | 2008 |
| Business Assist (GB) Limited | Other services | 2009 |
| Business Excellence Systems Limited | Professional & scientific | 2024 |
| Business Master Education Development Limited | Education | 2023 |
| Business Solutions Intl Ltd | Professional & scientific | 2013 |
| Business Trading & Investments L.P. | | 2019 |
| Butler Cesave Ltd | Wholesale & retail | 2025 |
| Butlers Management Services Ltd | Real estate | 2025 |
| Butterfly OT Ltd | Education | 2025 |
| Butterfly Touch Care Ltd | Health & social care | 2026 |
| Butterworth Confectionery Sales Limited | Administrative & support | 2016 |
| Buy My Holiday Ltd | Administrative & support | 2023 |
| Buzhoushan Industrial Co., Ltd | Extraterritorial | 2021 |
| Buzz Hubz Ltd | Wholesale & retail | 2024 |
| Buzzdrive Ltd | Administrative & support | 2014 |
| Buzzer Player Ltd | Wholesale & retail | 2025 |
| Bvrt Ltd | Wholesale & retail | 2015 |
| BW & AB Ltd | Transport & logistics | 2020 |
| BWC Wholesale Ltd | Wholesale & retail | 2019 |
| Bwmf Ltd | Wholesale & retail | 2025 |
| BWY Business With YOU Consulting and Representation Ltd | Professional & scientific | 2022 |
| Bxtplumbing Limited | Construction | 2025 |
| BY AMI Beauty Studio Ltd | Other services | 2025 |
| BY Jipang Co., Limited | Professional & scientific | 2010 |
| BY Marc Ltd | Wholesale & retail | 2025 |
| BY Oliver Furniture Ltd | Wholesale & retail | 2025 |
| BY Sasha Ltd | Wholesale & retail | 2024 |
| Bydesign Privacy Ltd | Professional & scientific | 2025 |
| BYK Mall Limited | Wholesale & retail | 2025 |
| Bynoi Ltd | Wholesale & retail | 2025 |
| Byrhtnoth Ironworks Ltd | Wholesale & retail | 2025 |
| Byte Light Year Ltd | Arts & recreation | 2025 |
| Byte Pixel Ltd | Information & communication | 2025 |
| Byte TAO Dynamics Ltd. | Wholesale & retail | 2025 |