| Bhan Thai (UK) Ltd | Hospitality | 2011 |
| Bhuvi Properties Ltd | Real estate | 2024 |
| Bickell Electrical Services Ltd | Construction | 2016 |
| Bickerton Court Management Company Limited | Households | 2016 |
| Bidshaper Limited | Professional & scientific | 2023 |
| Big Dave Productions Limited | Administrative & support | 2017 |
| Biggenius Limited | Extraterritorial | 2010 |
| BIL 6677 LLP | | 2010 |
| Bill Moule & Sons Limited | Construction | 1980 |
| Billing Associates Limited | Real estate | 1998 |
| Binns Fencing Limited | Construction | 1950 |
| Binns Group Limited | Financial services | 2022 |
| BIO Yarn Ltd | Wholesale & retail | 2023 |
| Biogenetics & Tech Limited | Professional & scientific | 2022 |
| Biomedical Vascular Phantoms UK Limited | Professional & scientific | 2025 |
| Bioscience Ltd. | Other services | 2007 |
| Biotherapy Ltd | Health & social care | 2023 |
| Biovance Group Ltd | Information & communication | 2026 |
| Birch & Co Properties Limited | Real estate | 2025 |
| Birkin Court (WGC) Management Company Limited | Households | 2017 |
| Biscuit Crumbs Ltd | Information & communication | 2025 |
| Bizopus Technologies Ltd | Information & communication | 2011 |
| Biztek Properties Limited | Real estate | 2020 |
| Biztek Solutions Limited | Information & communication | 2012 |
| BJS Sport Ltd | Arts & recreation | 2015 |
| Black Diamond Inc Ltd | Transport & logistics | 2018 |
| Blackaby Consulting Ltd | Professional & scientific | 2026 |
| Blackhorse Ventures Ltd | Real estate | 2003 |
| Blackstone Administration Limited | Professional & scientific | 2018 |
| Blackstone Global Solutions Limited | Administrative & support | 2015 |
| Blackstone Property Investments Limited | Real estate | 2020 |
| Blackstone Realty Limited | Construction | 2019 |
| Blackthorn of Kent Ltd | Manufacturing | 2024 |
| Blakeney Court Freehold Limited | Real estate | 1998 |
| Blanco Plastering Ltd | Construction | 2026 |
| Blaxland Ltd | Real estate | 2004 |
| Blaze Executive Cars Limited | Transport & logistics | 2015 |
| Blenheim Crescent Limited | Households | 1983 |
| Blenheim Investments UK Limited | Real estate | 2007 |
| Block Meat London Ltd | Administrative & support | 2025 |
| Blocked Drains and Plumbing Ltd | Water & waste | 2016 |
| Bloom Resonance Limited | Information & communication | 2024 |
| Blossom Realty Ltd | Real estate | 2025 |
| Blossom Urbane Ltd | Information & communication | 2024 |
| Blue Apple Consulting Ltd | Professional & scientific | 2023 |
| Blue Flag Visual Limited | Arts & recreation | 2017 |
| Blue Frog Finance Limited | Financial services | 2017 |
| Blue Hope Talent Limited | Information & communication | 2022 |
| Blue Jigsaw Limited | Manufacturing | 2003 |
| Blue Marine Investment Ltd | Wholesale & retail | 2025 |
| Blue Milk Media Limited | Information & communication | 2015 |
| Blue Oyster - Leading Edge Solutions Limited | Real estate | 2003 |
| Blue Pear Marketing Ltd | Information & communication | 2019 |
| Bluebell Homes One Limited | Real estate | 2024 |
| Bluebell Homes Two Limited | Real estate | 2024 |
| Bluedot Clarity Ltd | Professional & scientific | 2018 |
| Bluekloud Limited | Professional & scientific | 2012 |
| Bluestones Capital Ltd | Real estate | 2025 |
| Blunt Foods Limited | Wholesale & retail | 2019 |
| Bmdl Ltd | Real estate | 2021 |
| Bmproductions UK Ltd | Information & communication | 2025 |
| Bodial Limited | Construction | 1995 |
| Bollands Estates Limited | Real estate | 2021 |
| BON Investments LLP | | 2025 |
| Boncomms Limited | Wholesale & retail | 2020 |
| Bond Financial Limited | Financial services | 2000 |
| Bond Insurance Services Limited | Financial services | 2005 |
| Bones Chicken Ltd | Hospitality | 2021 |
| Bones Chicken Popup Limited | Hospitality | 2023 |
| Bonlife Trading LLP | | 2026 |
| Booty Camp Ltd | Arts & recreation | 2013 |
| Boring Digital Limited | Information & communication | 2019 |
| Boris&Co Ltd | Professional & scientific | 2017 |
| Borne Construction and Developments Limited | Construction | 2022 |
| Borough Property Maintenance Limited | Construction | 1993 |
| BOS Outsourcing Limited | Information & communication | 2026 |
| Boucherie Gerard Limited | Administrative & support | 2004 |
| Boulevard Events Ltd | Hospitality | 2010 |
| BOW Lane Ents. Limited | Administrative & support | 1999 |
| Bowgate Mews Management Company Limited | Real estate | 2022 |
| Box 5 Limited | Real estate | 2006 |
| Boxing With the Stars Limited | Administrative & support | 2017 |
| Boxwood Park Management Limited | Households | 2021 |
| Boycey Pictures Limited | Arts & recreation | 2014 |
| Bozier Limited | Information & communication | 2008 |
| BPA Ltd | Information & communication | 1999 |
| BQV Consultancy Services Limited | Information & communication | 2019 |
| Brackens Elite Property Management Limited | Real estate | 2002 |
| Brant Interims Limited | Information & communication | 2021 |
| Branter Limited | Professional & scientific | 2006 |
| BRB Real Estate Ltd | Real estate | 2016 |
| Bridge Court (Mutton Lane) RTM Ltd | Households | 2018 |
| Bridges Forwarding Limited | Transport & logistics | 2024 |
| Bright Light Innovation Limited | Professional & scientific | 2007 |
| Brightfields Academy Ltd | Education | 2025 |
| Brightminds Tech Ltd | Education | 2026 |
| Brighton 2020 Limited | Real estate | 2020 |
| Brighton Roosts Limited | Professional & scientific | 2019 |
| Brightsam Limited | Real estate | 2017 |
| Brilliant Visible Star Limited | Information & communication | 2012 |