| Broadway Travel Service(Wimbledon)Limited | Administrative & support | 1949 |
| Brodies Logistics Ltd | Transport & logistics | 2026 |
| Bromarsh Court Residents Association Limited | Real estate | 2005 |
| Bromley Property Holdings Limited | Professional & scientific | 2000 |
| Bromley Property Investments Limited | Professional & scientific | 2000 |
| Bronsgeest Ltd | Health & social care | 2011 |
| Brook Cottage Holdings Limited | Financial services | 2021 |
| Brookcade Limited | Wholesale & retail | 2021 |
| Brookfield (Acklam) Management Company Limited | Households | 2014 |
| Brookfield Consultancy Services Limited | Professional & scientific | 2026 |
| Brookfield Medical Services Limited | Health & social care | 2023 |
| Brookwater Beverages Ltd | Wholesale & retail | 2026 |
| Broom & Co Limited | Other services | 2025 |
| Broomhaugh Developments Limited | Construction | 2016 |
| Brou Services Ltd | Construction | 2016 |
| Brough Partners Limited | Professional & scientific | 2018 |
| Brouhaha Ltd | Wholesale & retail | 2020 |
| Brow Game TLV Ltd | Other services | 2023 |
| Browandlashstudioco Ltd | Other services | 2025 |
| Browell Smith & Co Solicitors Ltd | Professional & scientific | 2010 |
| Browell Smith & Co. LLP | | 2010 |
| Brown & Co Grooming Ltd | Other services | 2019 |
| Brown and Bond Property Ltd | Real estate | 2022 |
| Brown and Illingworth Limited | Transport & logistics | 2011 |
| Brown FOX Lettings Limited | Real estate | 2021 |
| Brown Knight & Truscott Limited | Manufacturing | 1992 |
| Brown, March and Bowman Ltd | Professional & scientific | 2018 |
| BRS General Trading Limited | Wholesale & retail | 2025 |
| BRT Motor Group Limited | Wholesale & retail | 2019 |
| Bruce & Co Legal & Financial Ltd. | Professional & scientific | 2001 |
| Bruce & Co. Wills & Trusts Ltd | Professional & scientific | 2006 |
| BRUNCH23 Ltd | Hospitality | 2023 |
| Brundibár Arts Festival Limited | Arts & recreation | 2015 |
| Brunswick Blinds Limited | Wholesale & retail | 2021 |
| Brunswick Coffee Shop Limited | Hospitality | 2009 |
| Brunswick Dental Practice Ltd | Health & social care | 2025 |
| Brunswick Energy Ltd | Wholesale & retail | 2020 |
| Brunton Electrical Services Ltd | Manufacturing | 2025 |
| Brunton Group Limited | Professional & scientific | 2009 |
| Brunton Grove Management Limited | Households | 1983 |
| Brunton Holdings Limited | Professional & scientific | 2015 |
| Brunton Pharmacy Limited | Wholesale & retail | 2025 |
| Brunton Place Management Company Limited | Households | 2019 |
| Brunton Project Management Consultants Limited | Professional & scientific | 2016 |
| Brunton Residential Ltd | Real estate | 2017 |
| Brunton Woods Management Company Limited | Real estate | 2021 |
| Brush Technology Limited | Manufacturing | 1990 |
| Bruvvers Theatre Company | Arts & recreation | 1993 |
| Bryan Does Food Ltd | Hospitality | 2023 |
| Bryan Mccormick Limited | Health & social care | 1986 |
| Bryce Energy Services Ltd | Professional & scientific | 2020 |
| Bryn Bowden Solutions Limited | Construction | 2023 |
| Bryonn Architecture Ltd | Professional & scientific | 2014 |
| Bryony Gibson Consulting Limited | Administrative & support | 2013 |
| BS Northeast Ltd | Wholesale & retail | 2022 |
| Bs&P Ltd | Administrative & support | 2009 |
| BSB Cleaning Solutions Ltd | Administrative & support | 2026 |
| BSC Weddings Ltd | Professional & scientific | 2019 |
| Bsetsam Ltd | Hospitality | 2023 |
| Bsfc Limited | Wholesale & retail | 2016 |
| Bsge Co Limited | Professional & scientific | 2020 |
| Bsgi Tradco Limited | Administrative & support | 2024 |
| BSL Communications Limited | Professional & scientific | 2026 |
| BSL Medical Services Limited | Health & social care | 2015 |
| Bspk Flooring Ltd | Wholesale & retail | 2019 |
| BSS Newcastle Ltd | Other services | 2026 |
| Bssb Innovation (UK) Limited | Other services | 2018 |
| BT Shopfitting Limited | Construction | 2014 |
| BTS Aesthetics Ltd | Health & social care | 2017 |
| Btsrecruitment&Training Ltd | Administrative & support | 2024 |
| Bubbas BBQ Ltd | Hospitality | 2025 |
| Bubble Boots Football Ltd | Hospitality | 2015 |
| Bubble Boots Parties Ltd | Health & social care | 2022 |
| Bubble CHA Limited | Hospitality | 2012 |
| Bubble Hospitality Marketing Limited | Professional & scientific | 2018 |
| Bubble T Break Ltd | Hospitality | 2015 |
| Bubble T-Lab Ltd | Hospitality | 2024 |
| Bubbles and FUR Ltd | Extraterritorial | 2025 |
| Buckland Building Developments Limited | Construction | 2026 |
| Bucklebox Ltd | Extraterritorial | 2007 |
| Buckleys' Solutions Ltd | Real estate | 2025 |
| Buckton Fields (Northampton) Apartment Management Company Limited | Real estate | 2022 |
| Buckton Fields (Northampton) Estate Management Company Limited | Real estate | 2022 |
| BUD N Stud Limited | Wholesale & retail | 2023 |
| Buddin Drum Software Ltd | Information & communication | 2025 |
| Budget Apartments Newcastle Ltd | Real estate | 2019 |
| Budget Leisure UK Limited | Hospitality | 2015 |
| Budget Storage Newcastle Limited | Other services | 2016 |
| Budget Workwear UK Ltd | Wholesale & retail | 2020 |
| Budstore Ltd | Wholesale & retail | 2023 |
| Buetti Ltd | Wholesale & retail | 2023 |
| Buffet Box Ltd | Hospitality | 2019 |
| BUG BUG Group Ltd | Administrative & support | 2025 |
| Build & Plumb Limited | Extraterritorial | 2025 |
| Build (NE) Ltd | Construction | 2019 |
| Build a Buddy World Limited | Manufacturing | 2025 |
| Build Alter Improve Ltd | Construction | 2019 |
| Build and Bloom Marketing Limited | Professional & scientific | 2026 |
| Build by Choice Ltd | Construction | 2022 |
| Build Planet Zero Limited | Professional & scientific | 2022 |