| Brookson Projects Limited | Administrative & support | 2006 |
| Brookson Solutions Limited | Professional & scientific | 2006 |
| Brookstone Walk Residents Management Company Limited | Households | 2026 |
| Brookwood Homes Limited | Wholesale & retail | 2001 |
| Broomfields Youth Project | Education | 2012 |
| Brothers Bathrooms Ltd | Construction | 2025 |
| Brothers Grim Limited | Professional & scientific | 2025 |
| Broughton Lubricants Limited | Extraterritorial | 2020 |
| Brow Power Ltd | Other services | 2019 |
| Brown & Forth Limited | Wholesale & retail | 1968 |
| Brown Gorman LLP | | 2021 |
| Brown Lettings Ltd | Real estate | 2024 |
| Brownburn Ltd | Information & communication | 2025 |
| Brownlee DS Limited | Administrative & support | 2025 |
| Browns Contract Furniture Ltd | Other services | 2012 |
| Browsers Beds Ltd | Wholesale & retail | 2025 |
| BRP Project Management Ltd | Professional & scientific | 2017 |
| Bruche Associates Limited | Professional & scientific | 2016 |
| Bruche Heath Laundry Services Limited | Administrative & support | 2025 |
| Bruche Joinery Limited | Construction | 2005 |
| Bruche Motors Limited | Wholesale & retail | 1978 |
| Brunch (Birchwood) Limited | Hospitality | 2020 |
| Brunch (Deeside) Ltd | Hospitality | 2024 |
| Brunch (Haydock) Ltd | Hospitality | 2024 |
| Brunch (NW) Limited | Hospitality | 2011 |
| Brunch Hospitality Limited | Financial services | 2026 |
| Brundavanam Properties Ltd | Real estate | 2025 |
| Bruno 39 Ltd | Administrative & support | 2026 |
| Brushfield Limited | Information & communication | 1995 |
| Bryant Design Services Limited | Administrative & support | 2012 |
| Brynmed Limited | Health & social care | 2008 |
| Brynrhyd Solar Farm Limited | Other services | 2019 |
| Brysa Limited | Professional & scientific | 2018 |
| Brysa Mediaops Limited | Professional & scientific | 2025 |
| BSC Property Group Ltd | Financial services | 2025 |
| BSC Signs Ltd | Manufacturing | 2020 |
| BSL Strategic Limited | Real estate | 2014 |
| BSS Dhuck Limited | Administrative & support | 2014 |
| Bssa Investment Limited | Real estate | 2017 |
| BSV Properties Limited | Real estate | 2023 |
| BT Howl Joinery & Carpentry Limited | Manufacturing | 2026 |
| Btass Ltd | Administrative & support | 2024 |
| BTH Lifting Limited | Administrative & support | 2020 |
| Btlr Property Ltd | Real estate | 2024 |
| Btmnt Limited | Professional & scientific | 2017 |
| BTS NQ Ltd | Construction | 2017 |
| BTS Services Group Limited | Manufacturing | 2017 |
| BTY Boxing Ltd | Education | 2024 |
| Bubba & Mouse Ltd | Administrative & support | 2022 |
| Bubble Five Ltd | Other services | 2013 |
| Bubble Four Ltd | Other services | 2012 |
| Bubble Three Ltd | Other services | 2013 |
| Buchan's Kennels & Structures Ltd | Administrative & support | 2017 |
| Buchanan Consulting Limited | Professional & scientific | 2019 |
| Buckinghamshire Properties Limited | Construction | 1992 |
| Buckley Brick Services Ltd | Construction | 2023 |
| Buckthorn London Limited | Hospitality | 2018 |
| Budget Scaffolding UK Limited | Construction | 2022 |
| Budova Management Ltd | Real estate | 2024 |
| Budworth Estates Limited | Real estate | 2024 |
| Budworth Mechanical Ltd | Professional & scientific | 2017 |
| Budworth Property Services Ltd | Construction | 2017 |
| Buffalo HK Cafe Ltd | Hospitality | 2025 |
| Bugberry Limited | Real estate | 2022 |
| Building & Asset Condition Surveys Limited | Professional & scientific | 2014 |
| Building Envelope Integrity Testing Assciation Ltd | Professional & scientific | 2013 |
| Building Future Services Ltd | Real estate | 2019 |
| Building Modelling and Detailing Ltd | Construction | 2011 |
| Building Solutions Warrington Ltd | Energy | 2023 |
| Building, Maintenance & Facilities Ltd | Construction | 2026 |
| Buildings 2 Clean Ltd | Administrative & support | 2007 |
| Buildnet Northwest Limited | Real estate | 2025 |
| Bull & Tutey Ltd | Information & communication | 2019 |
| Bullaminda Limited | Professional & scientific | 2021 |
| Bulldog Equipment Limited | Extraterritorial | 2013 |
| Bulldog Event Crew London Ltd | Administrative & support | 2024 |
| Bulldog Industrial Holdings Limited | Wholesale & retail | 1993 |
| Bulldog Machinery Limited | Extraterritorial | 2013 |
| Bulldog Mailing Ltd | Professional & scientific | 2024 |
| Bullet Car Repairs Ltd | Wholesale & retail | 2017 |
| Bullett Pharma Consulting Ltd | Professional & scientific | 2022 |
| Bullock Development Limited | Information & communication | 2022 |
| Bulwark Financial Services Limited | Financial services | 2004 |
| Bumblebee Maintenance Ltd | Construction | 2018 |
| Bumblebee Plumbing & Heating Ltd | Construction | 2015 |
| Bump BPM Ltd | Manufacturing | 2023 |
| Bump to Bundle Limited | Other services | 2018 |
| Bundu Fashion & Creative Consultancy Ltd | Administrative & support | 2023 |
| Bunnyhopp Express Limited | Transport & logistics | 2026 |
| Burbidge Enterprises Limited | Professional & scientific | 2020 |
| Bureau Services LLP | | 2017 |
| Bureau Veritas Consumer Products Services UK Limited | Administrative & support | 1965 |
| Burford Lane Veterinary Centre Limited | Professional & scientific | 2021 |
| Burgbites Ltd | Hospitality | 2024 |
| Burgess Care Limited | Health & social care | 1996 |
| Burgess Removals Ltd | Transport & logistics | 2023 |
| Burgess Wood Investments Limited | Financial services | 2023 |
| Burke-T Digital Consulting Ltd | Information & communication | 2022 |
| Burleigh House Limited | Health & social care | 2008 |
| Burleighs Group Ltd | Real estate | 2017 |