| Box 2 Box Sports Ltd | Arts & recreation | 2016 |
| Boxed Acquisitions Limited | Real estate | 2021 |
| Boxerdome Limited | Wholesale & retail | 2006 |
| Boxgraft Steward Limited | Extraterritorial | 2000 |
| Boxtree 42 Ltd | Real estate | 2020 |
| Boyan & Co Limited | Information & communication | 2014 |
| Bozz Security and Training Ltd. | Transport & logistics | 2018 |
| BP Housing Ltd | Real estate | 2024 |
| BP Tank Limited | Households | 2013 |
| BPA Search International Limited | Administrative & support | 2010 |
| Bphd Properties Limited | Real estate | 2017 |
| BPM100 Ltd | Arts & recreation | 2018 |
| BPR Decorators Limited | Wholesale & retail | 2009 |
| BPS Consultant Ltd | Information & communication | 2020 |
| BPT (Southern) Limited | Real estate | 1999 |
| BPW Corporate Limited | Professional & scientific | 2023 |
| BQ Medical Limited | Health & social care | 2023 |
| BR 21 Ltd | Wholesale & retail | 2025 |
| BR Patel Limited | Wholesale & retail | 2013 |
| BR Spices Ltd | Hospitality | 2024 |
| Braces & Beats Limited | Health & social care | 2024 |
| Bracken UK Limited | Real estate | 1998 |
| Brackenhill Developments Limited | Construction | 2011 |
| Brackmills Limited | Wholesale & retail | 2016 |
| Braconhyrst RTM Company Limited | Households | 2024 |
| Bradbury Commercial Management Ltd | Real estate | 2019 |
| Bradgate View Limited | Financial services | 2020 |
| Bradley Digital Limited | Professional & scientific | 2019 |
| Bradmead Estates Ltd | Real estate | 2024 |
| Bradmoor Hatcheries Limited | Wholesale & retail | 2008 |
| Bradshaw Middleton & Jones Ltd | Professional & scientific | 2019 |
| Brahm Mirror Creations Ltd | Manufacturing | 2026 |
| Brahmani Store Limited | Wholesale & retail | 2025 |
| Brain HUG Ltd. | Information & communication | 2016 |
| Brainacular Limited | Education | 2025 |
| Brainbee Limited | Information & communication | 2019 |
| Brainpower Technologies Ltd | Information & communication | 2014 |
| Braintree Property Limited | Real estate | 2019 |
| Brainwork Technologies Ltd | Information & communication | 2024 |
| Brainy Healthcare Ltd | Wholesale & retail | 2025 |
| Braj Vikas Properties Ltd | Real estate | 2017 |
| Brama Care Ltd | Health & social care | 2015 |
| Bramald Limited | Administrative & support | 2001 |
| Bramatech Limited | Information & communication | 2025 |
| Brams Residential Limited | Real estate | 2025 |
| Bramshaw Scientific and Technical Services Ltd | Professional & scientific | 2023 |
| Brand and Trade Developers Ltd | Professional & scientific | 2025 |
| Brand Design Studio Ltd | Professional & scientific | 2025 |
| Brand Evangelicals Ltd | Information & communication | 2020 |
| Brand Expression Limited | Professional & scientific | 2024 |
| Brand Founder Ltd | Professional & scientific | 2023 |
| Brand Managers Limited | Extraterritorial | 2000 |
| Brand One Ventures Ltd | Wholesale & retail | 2021 |
| Brand Purist Ltd | Professional & scientific | 2012 |
| Brand Theorem Limited | Professional & scientific | 2025 |
| Brand UP Ltd | Extraterritorial | 2006 |
| Brandan House Freehold Limited | Households | 2011 |
| Brandon House Limited | Real estate | 2017 |
| Brandon Mead (2) Management Limited | Real estate | 2012 |
| Brands Express UK Limited | Wholesale & retail | 2015 |
| Brandscapes Worldwide Consultancy Services Limited | Professional & scientific | 2017 |
| Brandvine Ltd | Wholesale & retail | 2011 |
| Brannigan Limited | Extraterritorial | 2003 |
| Brar Entertainment Limited | Information & communication | 2021 |
| Brass House Entertainment Ltd | Arts & recreation | 2020 |
| Brattle Investments Limited | Financial services | 2022 |
| Braude Wealth Management Limited | Financial services | 2013 |
| Bravas London Limited | Extraterritorial | 2013 |
| Bravas Properties Limited | Real estate | 2022 |
| Brave Falcon Limited | Hospitality | 2015 |
| Brave Private Ltd | Real estate | 2016 |
| Braver Solutions Limited | Health & social care | 2020 |
| Bray Consortium Limited | Hospitality | 2016 |
| Braytech Limited | Construction | 1996 |
| Braywick Limited | Professional & scientific | 2020 |
| Brazee Solutions Limited | Professional & scientific | 2018 |
| BRB Build&Craft Ltd | Construction | 2026 |
| BRC Estate Limited | Real estate | 2026 |
| Bread Boss Ltd | Manufacturing | 2015 |
| Bread on the Rise Limited | Real estate | 2022 |
| Breadcrumb News Limited | Information & communication | 2026 |
| Breaking Trends Limited | Professional & scientific | 2002 |
| Breakspear Technologies Ltd | Information & communication | 2014 |
| Breakthrough Family Law Ltd | Professional & scientific | 2012 |
| Breakthrough Global Trading Ltd | Wholesale & retail | 2017 |
| Breakthrough Studios Limited | Information & communication | 2025 |
| Breakwater Consulting Limited | Financial services | 2016 |
| Breast Clinic London Ltd. | Health & social care | 2022 |
| Breathe Fitness Limited | Arts & recreation | 2019 |
| Breathease Health Ltd | Health & social care | 2025 |
| Breathitate Ltd | Information & communication | 2023 |
| Brelon Limited | Professional & scientific | 2020 |
| Bremgreen Properties Limited | Construction | 2000 |
| Bren Thaven UK Limited | Wholesale & retail | 2022 |
| Brendons LLP | | 2004 |
| Brendons Property Consultants Limited | Professional & scientific | 1992 |
| Brent and Harrow Chamber of Commerce Ltd | Other services | 1997 |
| Brevino Limited | Wholesale & retail | 2025 |
| Brew Haven Hospitality Ltd | Construction | 2020 |
| Brewed Bliss Ltd | Hospitality | 2025 |