| Brookfield Strategies Limited | Professional & scientific | 2020 |
| Brookline Capital Ltd | Real estate | 2021 |
| Brookman Holdings Limited | Financial services | 2023 |
| Brookman Investments Limited | Professional & scientific | 2008 |
| Brookmans Park Osteopathy Limited | Health & social care | 2005 |
| Brookson (5152C) Limited | Administrative & support | 2007 |
| Brosnan & SON Storage & Removals Limited | Transport & logistics | 1999 |
| Bross Brener Ltd | Construction | 2018 |
| Brough Gardens Limited | Administrative & support | 2018 |
| Browning and Spice Ltd | Manufacturing | 2026 |
| Bruds’ Girls Limited | Wholesale & retail | 2019 |
| Brutus Consulting Ltd | Information & communication | 2015 |
| Brvconstruct Ltd | Construction | 2022 |
| Brázdová IP Limited | Professional & scientific | 2025 |
| BSI Electrics Limited | Construction | 2010 |
| BSM Car Transport Ltd | Transport & logistics | 2016 |
| BT BIM Limited | Construction | 2026 |
| BTH & Sons Developments Limited | Real estate | 2020 |
| BTM Construction & Civils Limited | Construction | 2026 |
| Bubble Hub Limited | Real estate | 2018 |
| Buchanan (86) DCL Ltd | Real estate | 2016 |
| Buchanan DCL Ltd | Real estate | 2016 |
| Buckingham Court (ST Albans) Limited | Households | 2000 |
| Buckingham House Andover Ltd | Real estate | 2023 |
| Bucklers Hard Boat Builders Limited | Manufacturing | 1971 |
| BUD HR Limited | Information & communication | 2023 |
| BUD Rescue & Recovery Limited | Other services | 2004 |
| Budget Numbers Limited | Information & communication | 2004 |
| Build Clean Xperts Ltd | Administrative & support | 2019 |
| Build Public Relations Ltd | Professional & scientific | 2013 |
| Buildgrowlast Ltd | Other services | 2023 |
| Building 1 Zone Limited | Other services | 2015 |
| Builtbybruce Ltd | Construction | 2024 |
| Bulbruin Limited | Administrative & support | 1976 |
| Bumpy Property Management Ltd | Real estate | 2025 |
| Bunavoneader Hydro Limited | Energy | 2013 |
| Burbage Avenue Limited | Administrative & support | 2013 |
| Burgess Memorials Limited | Other services | 2002 |
| Burgundy Developments Limited | Construction | 2008 |
| Burgundy Homes Ltd | Real estate | 2015 |
| Burleigh Old Dairy Flats Management Company Limited | Households | 2011 |
| Burrows Property Services Ltd | Construction | 2025 |
| Burston Aquatics Limited | Extraterritorial | 2021 |
| Burston Garden Centre Limited | Extraterritorial | 2016 |
| Burston Nurseries Limited | Wholesale & retail | 1963 |
| Burton Wealth Management Limited | Financial services | 2011 |
| BUS Stop Media Ltd | Information & communication | 2021 |
| Bushey Catering Limited | Hospitality | 2025 |
| Bushley Limited | Extraterritorial | 1984 |
| Business Disputes Solutions Ltd | Information & communication | 2010 |
| Business Growth Partners Limited | Other services | 2002 |
| Business Solutions RG Ltd | Information & communication | 2015 |
| Businesses Work Limited | Wholesale & retail | 2008 |
| Businesses Work Trading Limited | Wholesale & retail | 2023 |
| Businessscope Consultancy Ltd | Administrative & support | 2005 |
| Butterfly and Dragonfly Ltd | Information & communication | 2025 |
| Butterwick Investments Limited | Real estate | 1959 |
| Butterworth Construction Limited | Construction | 2014 |
| Buy Fine Art Limited | Wholesale & retail | 2023 |
| Buzz Beestro Ltd | Hospitality | 2023 |
| Buzzhire Limited | Administrative & support | 2009 |
| Buzzmint Limited | Information & communication | 2021 |
| BWA Immigration and Asylum Consultants Ltd | Other services | 2024 |
| BWH Construction Ltd | Construction | 2018 |
| BY Biology Ltd | Wholesale & retail | 2022 |
| BY Florence Design Ltd | Professional & scientific | 2020 |
| BY George Limited | Information & communication | 2007 |
| BY the Sea Supported Holidays Ltd | Administrative & support | 2014 |
| BY Two Studio Limited | Professional & scientific | 2026 |
| Byfleet Solna Limited | Professional & scientific | 1963 |
| Byld II LP | | 2025 |
| Byld Ventures I LP | | 2022 |
| Bymarsi Boutique Ltd | Manufacturing | 2025 |
| BYN Consulting Limited | Information & communication | 2025 |
| Byron Blake Limited | Real estate | 2014 |
| Byron DCL Ltd | Real estate | 2016 |
| BYRON(2A) DCL Ltd | Real estate | 2016 |
| Bytewise Consulting Ltd. | Information & communication | 2017 |
| Byview Investments Limited | Households | 1962 |
| C & E W Mobile Homes Limited | Real estate | 2004 |
| C a H Construction Limited | Construction | 2017 |
| C B Management Limited | Professional & scientific | 1998 |
| C D Turner Limited | Administrative & support | 2015 |
| C DEM Finance Limited | Professional & scientific | 2018 |
| C Demurrage Limited | Professional & scientific | 2014 |
| C Godfrey Plumbing Services Ltd | Construction | 2010 |
| C J London Properties Ltd | Real estate | 2014 |
| C J Watson Limited | Wholesale & retail | 2003 |
| C Leeming Limited | Professional & scientific | 2019 |
| C M C Consulting Limited | Administrative & support | 1994 |
| C Perkins Children's Physiotherapy Ltd | Other services | 2019 |
| C R E Industrial Developments Limited | Construction | 2018 |
| C Solutions (Holdings) Limited | Professional & scientific | 2020 |
| C Solutions Energy Limited | Professional & scientific | 2017 |
| C Solutions Group Limited | Professional & scientific | 2017 |
| C Solutions Limited | Professional & scientific | 2000 |
| C Support Limited | Professional & scientific | 2008 |
| C&C Construction Hertfordshire Ltd | Construction | 2024 |
| C&C Leak Detection Ltd | Professional & scientific | 2026 |
| C&D General Building Limited | Construction | 2024 |