| Bosskay Group Ltd | Other services | 2017 |
| Bossperiperi Limited | Hospitality | 2021 |
| Bostontm Construction Ltd | Construction | 2023 |
| Bosworth Projects Limited | Administrative & support | 2018 |
| BOT Market Ltd | Financial services | 2025 |
| Botanic Homes Ltd | Real estate | 2022 |
| Botanic London Beauty Ltd | Other services | 2020 |
| Botaniplex Ltd | Wholesale & retail | 2026 |
| Both / and Limited | Hospitality | 2017 |
| Botpen Ltd | Construction | 2024 |
| Botwits Ltd | Wholesale & retail | 2025 |
| Botzen Ltd | Information & communication | 2025 |
| Boujee X Limited | Wholesale & retail | 2018 |
| Boulevard Dental Care Ltd | Health & social care | 2015 |
| Bounce Teachers Ltd | Administrative & support | 2022 |
| Bouncycastle Soft Play Limited | Administrative & support | 2026 |
| Boundary Real Estate Limited | Real estate | 2024 |
| Bounty F Docs Ltd. | Administrative & support | 2022 |
| Bourne Logistics Ltd | Administrative & support | 2016 |
| Bournesand Limited | Professional & scientific | 2001 |
| Boutique Express Ltd | Wholesale & retail | 2024 |
| Bovingdon Inns Ltd | Hospitality | 2017 |
| BOW Bells Cafe Ltd | Hospitality | 2023 |
| Bowdens of London Ltd | Construction | 2019 |
| Bower House Limited | Construction | 2018 |
| Box Office Events Ltd | Arts & recreation | 2018 |
| Box Trans Ltd | Transport & logistics | 2019 |
| Boxlab Health & Fitness Limited | Other services | 2022 |
| Boxmoor Capital Ltd | Real estate | 2014 |
| Boxmoor Estate Management Ltd | Other services | 2015 |
| Boxmount Limited | Real estate | 2014 |
| BP Cherrybrook Ltd | Wholesale & retail | 2026 |
| BP Corporation Limited | Hospitality | 2016 |
| BP Energy Ltd | Construction | 2024 |
| BPI Hub Ltd | Professional & scientific | 2024 |
| BPM & Partners Limited | Professional & scientific | 2014 |
| Bpmg Limited | Real estate | 2011 |
| BR 4 Accountants Limited | Professional & scientific | 2023 |
| BR Specialist Limited | Real estate | 2008 |
| BR3AKFREE Limited | Health & social care | 2007 |
| Bradbury Ironmonger Ltd | Wholesale & retail | 2018 |
| Bradburys Hardware Ltd | Wholesale & retail | 2011 |
| Bradley Baylis Ltd | Real estate | 2019 |
| Bradworth Limited | Households | 1993 |
| Braidhouseuk Ltd | Other services | 2026 |
| Brainbox Tutoring Limited | Education | 2025 |
| Brainiac Social Ltd | Professional & scientific | 2023 |
| Brainiacademy Ltd | Education | 2026 |
| Brainmap Ltd | Information & communication | 2014 |
| Braintank Limited | Extraterritorial | 2011 |
| Braintree Technologies Limited | Information & communication | 2017 |
| Brainwave Training and Tuition Limited | Education | 2010 |
| Brak & Brak Limited | Extraterritorial | 2013 |
| Brake Stop HGV Limited | Transport & logistics | 2024 |
| Brana & Dharmi LLP | | 2024 |
| Branch Inns Ltd | Hospitality | 2018 |
| Branching Minds Limited | Education | 2025 |
| Brand + Fashion Limited | Wholesale & retail | 2019 |
| Brand Box London Ltd | Information & communication | 2025 |
| Brand Palace Ltd | Wholesale & retail | 2025 |
| Brandcrest Marketing Ltd | Professional & scientific | 2025 |
| Branded Authorised Distributors Ltd | Other services | 2013 |
| Branded Deals London Ltd | Wholesale & retail | 2025 |
| Brandesbury Ltd | Real estate | 2022 |
| Brandfactory London Limited | Professional & scientific | 2025 |
| Brandly Ltd | Professional & scientific | 2025 |
| Brandon Robertson Associates Ltd | Manufacturing | 2011 |
| Brands Arena Limited | Wholesale & retail | 2018 |
| Brandsclap Limited | Extraterritorial | 2017 |
| Brandsea Limited | Wholesale & retail | 2015 |
| Brandstad Consulting Ltd | Administrative & support | 2013 |
| Brandwork Ltd | Administrative & support | 2007 |
| Branscombe Properties Limited | Real estate | 2024 |
| Brase Limited | Wholesale & retail | 2021 |
| Brasilford Ltd | Wholesale & retail | 2021 |
| Brasjery Refrigeration Service Ltd | Manufacturing | 2019 |
| Brathwaite Accountants Ltd | Professional & scientific | 2024 |
| Brattle Wood Limited | Information & communication | 2023 |
| Brava Ltd | Water & waste | 2022 |
| Brave Accessories Limited | Other services | 2022 |
| Brave Hearts Consultants (UK) Limited | Professional & scientific | 2025 |
| Brave Hearts International Limited | Information & communication | 2019 |
| Brave Hearts Movies Limited | Information & communication | 2022 |
| Braveform Limited | Construction | 2009 |
| Bravewin Ltd | Hospitality | 2013 |
| Bravo Distributions Limited | Wholesale & retail | 2025 |
| BRAVO6 Security Ltd | Administrative & support | 2026 |
| Brawn Electrical Ltd | Construction | 2024 |
| Brazen Gameplay Limited | Information & communication | 2026 |
| BRB Kitchen Ltd | Hospitality | 2025 |
| Break ME Box Ltd | Wholesale & retail | 2026 |
| Breakdown Film Ltd | Information & communication | 2022 |
| Breaker Yard Limited | Information & communication | 2003 |
| Breamore Ltd | Real estate | 2026 |
| Breamore Properties Ltd | Real estate | 2026 |
| Breamore Road Freehold Ltd | Households | 2017 |
| Breeze Broadband Limited | Information & communication | 2018 |
| Breeze Telecommunications Ltd | Information & communication | 2015 |
| Breezy Solutions Ltd | Construction | 2025 |
| Breezy Trading Limited | Other services | 2018 |