| Body Mentors Holdings Limited | Financial services | 2022 |
| Body Mentors Mark Cross Limited | Arts & recreation | 2022 |
| Body Mindfulness Studio Limited | Arts & recreation | 2018 |
| Bogle’S Boilers & Bathrooms Ltd | Construction | 2025 |
| Boiler Breakdown Ltd | Manufacturing | 2013 |
| Boiler Cover Breakdown Limited | Manufacturing | 2013 |
| Boiler Engineer 4U Ltd | Construction | 2018 |
| Bolatti London Ltd | Other services | 2012 |
| Boleyn Management Company (Sutton) Limited | Households | 1987 |
| BON Sine UK Ltd | Hospitality | 2025 |
| Bonadi Limited | Manufacturing | 2025 |
| Bonanza Consulting Limited | Professional & scientific | 2026 |
| Bonfield Associates Limited | Professional & scientific | 2006 |
| Bonfield Investments Limited | Financial services | 2013 |
| Bookalu Ltd | Information & communication | 2020 |
| Booker Ward Limited | Real estate | 2017 |
| BOOKSMART4U Limited | Professional & scientific | 2014 |
| Boon Spares Ltd | Wholesale & retail | 2025 |
| Boostup Ltd | Wholesale & retail | 2018 |
| Booz R US Ltd | Wholesale & retail | 2014 |
| Border Rock Limited | Real estate | 2021 |
| Borimechkata Ltd | Transport & logistics | 2020 |
| Born to Bronze Ltd | Other services | 2025 |
| BOS Inc Ltd | Real estate | 2024 |
| Bosa Development Ltd | Construction | 2021 |
| Bosco Clothing Company Limited | Wholesale & retail | 2013 |
| Boston Books Limited | Professional & scientific | 2001 |
| Botanical Plants Ltd | Administrative & support | 2025 |
| Botara Property Ltd | Real estate | 2025 |
| Bottriell's Installations Ltd | Construction | 2022 |
| Boum Leisure Ltd | Hospitality | 1993 |
| Bouncebrook Logistics Limited | Transport & logistics | 2016 |
| Boutique Royale Limited | Wholesale & retail | 2025 |
| BOW Pathways C.I.C. | Education | 2024 |
| Bowmont Building Services Ltd | Construction | 2020 |
| Bowrington Investments Limited | Real estate | 2022 |
| Box & Co Consultancy Limited | Professional & scientific | 2020 |
| Boychev Construction Limited | Construction | 2018 |
| BP Management Consulting Ltd | Professional & scientific | 2026 |
| BPI Executive Ltd | Transport & logistics | 2026 |
| BPS Electrical Services Ltd | Construction | 2019 |
| BPS Property (UK) Limited | Real estate | 2016 |
| BRA1NBOX Ltd | Education | 2020 |
| Bradford Street Property Company Limited | Real estate | 2021 |
| Bradley Jenson Services Limited | Construction | 2013 |
| Braintree Heating Centre Limited | | 1967 |
| Brainy Enterprises Ltd | Other services | 2019 |
| Brambledon Limited | Professional & scientific | 2002 |
| Bran Caffe Ltd | Hospitality | 2012 |
| Branch Services Limited | Construction | 2020 |
| Brand Africa Ltd | Wholesale & retail | 2007 |
| Brasen Energies Ltd | Professional & scientific | 2026 |
| Brasscamp Technologies Ltd | Information & communication | 2025 |
| Brati Contractors Ltd | Construction | 2025 |
| Bravo Polishing Ltd | Construction | 2024 |
| Bray Court RTM Company Ltd | Households | 2022 |
| Brazil Commodities Trading Limited | Wholesale & retail | 2012 |
| Bread and Shutter Limited | Energy | 2007 |
| Brian Harkins Limited | Wholesale & retail | 1994 |
| Brian LEE Services Ltd | Professional & scientific | 2020 |
| Brian Perkins Builders Ltd | Construction | 2012 |
| Brick House Ventures Limited | Households | 2025 |
| Brickmasters Limited | Construction | 2008 |
| Bricks & Mortar Estates Ltd | Real estate | 2021 |
| Bridgecity Canterbury Ltd | Construction | 2022 |
| Bridgecity Serviced Apartments Limited | Real estate | 2020 |
| Bridgefield Capital Ltd | Other services | 2022 |
| Bridgefield Projects Limited | Professional & scientific | 2025 |
| Bridgelink Consultants Limited | Information & communication | 2013 |
| Bridgewater Capital Ltd | Real estate | 2012 |
| Bridgewater Design Limited | Construction | 2012 |
| Bridgewater Education Ltd | Education | 2012 |
| Bridgewater Support Properties Limited | Real estate | 2023 |
| Bridgewater Trading Limited | Professional & scientific | 2012 |
| Briefclub Limited | Education | 2022 |
| Bright Home London Limited | Transport & logistics | 2025 |
| Bright Ideas Food & Health Consulting Limited | Professional & scientific | 2014 |
| Bright Light Childrens Care Ltd | Health & social care | 2025 |
| Bright Plumbing & Heating Services Limited | Construction | 2021 |
| Brill Skills Ltd | Construction | 2018 |
| Brisco Business Ltd | Professional & scientific | 2021 |
| Bristol Tracker Limited | Education | 2024 |
| Brit Nova Innovations Ltd | Wholesale & retail | 2025 |
| Britbuypvt Ltd | Wholesale & retail | 2025 |
| Britecho Ltd | Wholesale & retail | 2025 |
| British Anderson Limited | Professional & scientific | 1999 |
| British Association for Screen Entertainment Limited | Other services | 1980 |
| British Weight Lifters Association | Arts & recreation | 1957 |
| Britmetrix Limited | Wholesale & retail | 2025 |
| Briyani Boss Limited | Hospitality | 2025 |
| Brock and Cole Limited | Real estate | 2024 |
| Brontide Limited | Information & communication | 2005 |
| Broogi Ltd | Wholesale & retail | 2021 |
| Brook Brown Developments Ltd | Construction | 2020 |
| Brook Fitness Ltd | Arts & recreation | 2026 |
| Brookes Chauffeur Services Limited | Information & communication | 2001 |
| Brooks Bros. Investments Limited | Real estate | 2023 |
| Brooks Bros. Properties Limited | Real estate | 2023 |
| Brooks Home & Paint Ltd | Administrative & support | 2024 |
| Brookville Consultants Limited | Professional & scientific | 2016 |