| Barton-Wright Ltd | Wholesale & retail | 2022 |
| Basra Medics UK Ltd | Health & social care | 2013 |
| Bateman Services Limited | Professional & scientific | 1977 |
| Bates Wharf (Southern) Ltd | Wholesale & retail | 1999 |
| Bates Wharf Boat Club Ltd | Arts & recreation | 2024 |
| Bats Cabs Global Limited | Administrative & support | 2019 |
| Battenberg Ltd | Information & communication | 2013 |
| Bay Plastics Limited | Manufacturing | 1988 |
| BCN Associates Ltd | Construction | 2005 |
| BE Leadership Ltd | Other services | 2014 |
| Beacon Homes Consultancy Limited | Administrative & support | 2015 |
| Beacon Hospitality Services Limited | Hospitality | 2013 |
| Beaconhomes Group Limited | Administrative & support | 2015 |
| Beacontree Limited | Financial services | 2004 |
| Beardsley Revill Partnership Limited | Administrative & support | 2011 |
| Beatswap Ltd | Wholesale & retail | 2026 |
| Beauty by Seerat Ltd | Other services | 2025 |
| Beckford Trading Ltd | Wholesale & retail | 2026 |
| Beech Hall Residents Association Limited | Households | 1984 |
| Beechleigh Promotions Limited | Administrative & support | 2007 |
| Behwell Ltd | Health & social care | 2026 |
| Beibl Limited | Wholesale & retail | 2018 |
| Bejoy Ltd | Wholesale & retail | 2023 |
| Bell HR Limited | Administrative & support | 2005 |
| Belsize Grange Residents RTM Company Limited | Real estate | 2016 |
| Bemark Blue Ltd | Professional & scientific | 2012 |
| Bendle Holdings Limited | Financial services | 2026 |
| Bennie Lifts Limited | Professional & scientific | 1934 |
| Bens Way Ltd | Transport & logistics | 2017 |
| Benwell Productions Ltd | Information & communication | 2024 |
| Bespoke Roofing Ltd | Construction | 2023 |
| Best Cabs Limited | Transport & logistics | 2023 |
| Bestmove Logistics Limited | Transport & logistics | 2010 |
| Bexley and Greenwich Healthcare Ltd | Public administration | 2022 |
| Beyond Wellness Clinic Ltd | Health & social care | 2024 |
| Beyondbuy Store Ltd | Wholesale & retail | 2023 |
| BG World Experience Limited | Other services | 2019 |
| BGI Supplies U.K Limited | Information & communication | 2022 |
| Bhandari Brothers (UK) Ltd | Other services | 2009 |
| Bike Hero Ltd | Administrative & support | 2021 |
| Bikers Essentials Limited | Administrative & support | 2026 |
| BIO Shield Solutions Ltd | Administrative & support | 2025 |
| Biotech UK Healthcare Limited | Professional & scientific | 2010 |
| Bitharmony Limited | Information & communication | 2026 |
| Black Pearl Creations Limited | Hospitality | 2026 |
| Blackwater Valley Industrial Park Management Limited | Real estate | 1997 |
| Blue Arrow Transport Limited | Administrative & support | 1999 |
| Blue Estate Agents London Limited | Other services | 2013 |
| Blue Willow Homes Limited | Hospitality | 2019 |
| Blue Yeti Scenic Carpentry Ltd | Manufacturing | 2025 |
| Bluebelle Designs Walton Limited | Wholesale & retail | 2011 |
| Bluebird Creative Events Ltd | Administrative & support | 2014 |
| Bluede Motors Ltd | Wholesale & retail | 2025 |
| Blueview Group Limited | Administrative & support | 2020 |
| BM Trading Ltd | Wholesale & retail | 2019 |
| Body and Beyond Ltd | Wholesale & retail | 2024 |
| Boga Ltd | Hospitality | 2023 |
| Bogieville Limited | Information & communication | 2022 |
| Bond Education Cambridge Ltd | Other services | 2017 |
| Bond Education Limited | Administrative & support | 2013 |
| Bond Recruitment Services Limited | Administrative & support | 2009 |
| Boomrang E Solutions & Services Private Ltd | Other services | 2016 |
| Bosmosis Consulting Limited | Professional & scientific | 2021 |
| BQR Consulting Limited | Professional & scientific | 2011 |
| Bradford Gaines Limited | Administrative & support | 2018 |
| Brayan and Spencer Associates Group Limited | Professional & scientific | 2020 |
| Brayan and Spencer Associates Limited | Professional & scientific | 2012 |
| Breathe Online Ltd | Information & communication | 2020 |
| Bridge & Bark Limited | Other services | 2026 |
| Bridge Court (Radlett) Management Company Limited | Households | 1985 |
| Bright Production House Ltd | Information & communication | 2018 |
| Briony by Design Ltd | Hospitality | 2023 |
| Brisma Estate Ltd | Real estate | 2025 |
| Brne & Co Ltd | Wholesale & retail | 2024 |
| Broadcast Services Limited | Information & communication | 1990 |
| Broke Hack Ltd | Wholesale & retail | 2025 |
| Brook House Accountants Limited | Professional & scientific | 2025 |
| Brook House Auditors Ltd | Professional & scientific | 2023 |
| Brooke Development and Construction Ltd | Construction | 2024 |
| Brox Books Ltd | Information & communication | 2018 |
| Bryant Medical Ltd | Wholesale & retail | 2016 |
| Bucas International Limited | Administrative & support | 2017 |
| Buckingham Landscapes Limited | Administrative & support | 2003 |
| Buds FX Limited | Arts & recreation | 2021 |
| Buildasad Ltd | Construction | 2022 |
| Buildright Building & Maintenance Limited | Construction | 2004 |
| Bulbarrow Consultants Ltd | Professional & scientific | 2019 |
| Bullett Solutions Limited | Wholesale & retail | 2007 |
| Bunns Bootsales Corp Limited | Wholesale & retail | 2026 |
| Bunns Bootsales Ltd | Wholesale & retail | 2026 |
| Busy People Global Ltd | Administrative & support | 2025 |
| BVS Lifestyle Management Ltd | Administrative & support | 2025 |
| C & S Metals Ltd | Water & waste | 2025 |
| C.J. Smith (T.V. & Electrical) Limited | Wholesale & retail | 1978 |
| C2E Specialist Car Importers Limited | Wholesale & retail | 2015 |
| Cace Plumbing & Heating Ltd | Construction | 2025 |
| Cacique Africa Limited | Administrative & support | 2008 |
| Cadillac Plastic Limited | Wholesale & retail | 1982 |
| Cake Girl Café Limited | Hospitality | 2023 |
| Cake Girl Limited | Wholesale & retail | 2023 |