| Blue Jelly Limited | Administrative & support | 2002 |
| Blue Phoenix Services Limited | Administrative & support | 2021 |
| Blue Shield Holdings Limited | Professional & scientific | 2021 |
| Blue Space AI Limited | Professional & scientific | 2025 |
| Blue Squid Trading UK Limited | Wholesale & retail | 2017 |
| Bluebag Services Limited | Real estate | 2017 |
| Bluediamond Trading Limited | Wholesale & retail | 2012 |
| Blueyeuk LP | | 2015 |
| Blythswood Square Glasgow Hotel Opco Limited | Hospitality | 2018 |
| Bmfglobal Ltd | Wholesale & retail | 2021 |
| Bmic Operations Limited | Health & social care | 2017 |
| BOA BOA Wear Ltd | Wholesale & retail | 2022 |
| Bodhimaya Ltd | Health & social care | 2015 |
| Boleros Pizzeria Limited | Hospitality | 2021 |
| Bond Blue Company Limited | Hospitality | 2023 |
| Booze Bargain 1 Ltd | Wholesale & retail | 2019 |
| Born Trading Company Ltd | Professional & scientific | 2022 |
| Bottom-Up Construction Ltd | Construction | 2026 |
| Bouche Ltd | Hospitality | 2026 |
| Boulters Lock Management Company Limited | Households | 2007 |
| Boulters Management Limited | Real estate | 2013 |
| Boundlessip Networks Limited | Professional & scientific | 2006 |
| Bourne Marketing Consultancy Ltd | Professional & scientific | 2024 |
| Boutique by Lucy Ltd | Wholesale & retail | 2021 |
| Bovix Ltd | Construction | 2025 |
| Bowland Resources (NO.2) Limited | Mining & quarrying | 2008 |
| Bowland Resources Limited | Mining & quarrying | 2009 |
| Bowood One Ltd | Extraterritorial | 2022 |
| Bowood Ventures Ltd | Financial services | 2022 |
| Boxd Catering Limited | Hospitality | 2023 |
| Boyes Post Ltd | Information & communication | 2015 |
| Boyn Hill Avenue Management Company Limited | Households | 2013 |
| Boyne House (Beaconsfield) Management Company Limited | Households | 2001 |
| BPI on Demand Limited | Information & communication | 2008 |
| Bracknell Motors Ltd | Wholesale & retail | 2023 |
| Bradbury Surfacing Civils Limited | Construction | 2025 |
| Braemar Court Freehold Co Limited | Households | 2011 |
| Braemar Court Resident Company Limited | Households | 1992 |
| Brain Brew UK Limited | Manufacturing | 2018 |
| Brain Gainz Academy Ltd | Education | 2024 |
| Brain MAN Technologies Ltd | Information & communication | 2024 |
| Brains 2 Infinity Ltd | Extraterritorial | 2008 |
| Brainstorm Global Limited | Other services | 2024 |
| Brambleai Ltd | Information & communication | 2025 |
| Bramleys Interiors Limited | Wholesale & retail | 2010 |
| Bramleys Winkfield Limited | Administrative & support | 2009 |
| Branddna Limited | Professional & scientific | 2017 |
| Brandz Global Limited | Wholesale & retail | 2022 |
| Brawn Developments Ltd | Real estate | 2022 |
| Brawn Medical Ltd | Wholesale & retail | 2015 |
| Bray Property Limited | Real estate | 2006 |
| Braywood Consultancy Limited | Extraterritorial | 2021 |
| Brazenose Limited | Hospitality | 2009 |
| Brew & Beauty Co Ltd | Hospitality | 2024 |
| Brew Tower (Marlow) MAN. Co. Ltd | Households | 1997 |
| Brewup Coffee Ltd | Wholesale & retail | 2019 |
| Brextazy Official Ltd | Wholesale & retail | 2018 |
| Briab Consulting Limited | Professional & scientific | 2015 |
| Brick Designs Ltd | Manufacturing | 2022 |
| Brickies Club Franchise - Rbwm Ltd | Arts & recreation | 2024 |
| Bridge Street Freehold Ltd | Financial services | 2025 |
| Bridgend Golf Club Limited | Construction | 1985 |
| Bridgex Technology Limited | Information & communication | 2019 |
| Bright Leaf Distribution Ltd | Wholesale & retail | 2018 |
| Bright Sparks & SON Limited | Energy | 2013 |
| Brightpunch Ltd | Information & communication | 2012 |
| Britannia 2000 Holdings Limited | Professional & scientific | 2012 |
| Britannia Defence Systems Limited | Manufacturing | 2004 |
| Britannia Worldwide Express Limited | Transport & logistics | 2007 |
| British GAS Finance Limited | Administrative & support | 2009 |
| British GAS Insurance Limited | Financial services | 2008 |
| British GAS Limited | Energy | 2013 |
| British GAS New Heating Limited | Construction | 2008 |
| British GAS Services (Commercial) Limited | Construction | 2010 |
| British GAS Social Housing Limited | Construction | 1971 |
| Britsh R&D Limited | Professional & scientific | 2022 |
| Britsmotive Limited | Wholesale & retail | 2026 |
| Britzerland Ltd | Construction | 2022 |
| Brookfield View Management Company Limited | Households | 2007 |
| Brookson (5950J) Limited | Administrative & support | 2007 |
| Brown Bear Media Ltd | Information & communication | 2023 |
| BS.AS9 Limited | Hospitality | 2025 |
| BSZ Group UK Ltd | Professional & scientific | 2024 |
| Btwl CIC | Health & social care | 2023 |
| Build-Links Club Ltd | Information & communication | 2023 |
| Building Better H Limited | Real estate | 2024 |
| Building Better Humans Ltd | Arts & recreation | 2015 |
| Building Blocks London Limited | Administrative & support | 2014 |
| Building Doctor 24 Limited | Construction | 2024 |
| Built by KAY Ltd | Real estate | 2017 |
| Builtbyrowe Ltd | Other services | 2026 |
| Bula Productions Limited | Information & communication | 2014 |
| Buland Ltd | Real estate | 2020 |
| Bump to Bambino Limited | Wholesale & retail | 2018 |
| Burke Travel Services Ltd | Professional & scientific | 2024 |
| Burlington END Management Company Limited | Households | 2005 |
| Burnett International Search Group Ltd | Administrative & support | 2026 |
| Burnham Community Association | Health & social care | 2013 |
| Burnham Court (Burnham) Management Company Limited | Households | 2021 |
| Burnham Heights RTM Company Limited | Households | 2024 |