| Blessed London Ltd | Real estate | 2025 |
| Blessing Healthcare Limited | Health & social care | 2013 |
| BLG Transport Ltd | Transport & logistics | 2021 |
| Blondot Limited | Information & communication | 2017 |
| Blood and Bandages by MT Limited | Other services | 2016 |
| Bloom Room Studio Ltd | Extraterritorial | 2015 |
| Bloommerce Ltd | Wholesale & retail | 2025 |
| Blubell Ltd | Wholesale & retail | 2023 |
| Blue Bear Surrey Limited | Extraterritorial | 2025 |
| Blue Circle Events Limited | Other services | 2023 |
| Blue Data Management Ltd | Wholesale & retail | 2026 |
| Blue Light Business Consultancy Ltd | Administrative & support | 2023 |
| Blue Lizard Signs Limited | Manufacturing | 2005 |
| Blue Moon Hotels Procurement Services Limited | Manufacturing | 2014 |
| Blue Pepper Ltd | Wholesale & retail | 2020 |
| Blue Planet Washing Solutions Ltd | Administrative & support | 2021 |
| Blue Seafish Trading Ltd | Wholesale & retail | 2024 |
| Blue Sky Affinity Limited | | 2004 |
| Blue Star Accountancy Ltd | Professional & scientific | 2019 |
| Blue Star Resources Ltd | Administrative & support | 2019 |
| BLUEBELL7 Ltd | Other services | 2016 |
| Bluebird Chain & Findings Limited | Manufacturing | 1991 |
| Bluebox Learning Ltd | Education | 2016 |
| Bluefishents Ltd | Financial services | 2025 |
| Blueheaven Properties Ltd | Real estate | 2026 |
| Bluehold Limited | Professional & scientific | 1991 |
| Bluehorizon Transfers Limited | Transport & logistics | 2025 |
| Blueleaf Limited | Wholesale & retail | 2011 |
| Blueriver Ltd | Real estate | 2021 |
| Bluestar Care & Support Ltd | Health & social care | 2022 |
| Bluestar Housing Provider Ltd | Real estate | 2025 |
| Blugold Ltd | Administrative & support | 2014 |
| Bluron Ltd | Information & communication | 2025 |
| BM Air Vent Limited | Administrative & support | 2017 |
| BMC Plumbing Solutions Limited | Construction | 2024 |
| BMI Transport Services Ltd | Transport & logistics | 2021 |
| Bmrg Group Ltd | Financial services | 2022 |
| Bmrg Property Trading Ltd | Real estate | 2022 |
| BMY Properties Limited | Real estate | 2009 |
| BN Thermic Ltd | Manufacturing | 2005 |
| Bnstructures Ltd. | Construction | 2018 |
| Bob's Movement CIC | Other services | 2025 |
| Bobtold Ltd | Wholesale & retail | 2022 |
| Bode Electrical Limited | Construction | 2023 |
| Boden Group Ltd | Construction | 2022 |
| Bodfem Care Ltd. | Administrative & support | 2021 |
| Bodikind Ltd | Health & social care | 2020 |
| Body Art Events Limited | Hospitality | 2025 |
| Body Health Gatwick Limited | Health & social care | 2023 |
| Bodydexa Limited | Health & social care | 2024 |
| Bodyzen Therapeutics Ltd | Health & social care | 2025 |
| Boeing UK Training and Flight Services Holding Limited | Professional & scientific | 1999 |
| Boeing UK Training and Flight Services Limited | Transport & logistics | 1999 |
| Bogdan M Trans Ltd | Transport & logistics | 2020 |
| Bolo Service Ltd | Construction | 2015 |
| Bombay Style Biryani Limited | Hospitality | 2025 |
| Bond Raymonds Consultancy Ltd | Information & communication | 2022 |
| Bonnie Holdings Ltd | Real estate | 2022 |
| Bonwyck Driveways and Surfacing Ltd | Construction | 2019 |
| Bonwycks Business Park Ltd | Real estate | 2021 |
| Bonwycks Lodge Farm Ltd | Real estate | 2020 |
| Book Hill International Ltd | Wholesale & retail | 2021 |
| Booking Adventures Limited | Transport & logistics | 2021 |
| Bookkeeping Partner Limited | Professional & scientific | 2017 |
| Bookme Taxi Ltd | Transport & logistics | 2025 |
| Bootlegger Bar Supplies Ltd | Administrative & support | 2021 |
| Booysen Property Ltd | Real estate | 2025 |
| Booze Xpress Limited | Wholesale & retail | 2010 |
| Border Heating Limited | Wholesale & retail | 2000 |
| Border Oak Investments Limited | Financial services | 2023 |
| Borders of London Ltd | Information & communication | 2014 |
| Boujee Box Ltd | Wholesale & retail | 2024 |
| Bouka Limited | Professional & scientific | 2021 |
| Bounce Leisure Ltd | Hospitality | 2025 |
| Bournemouth Elite Cheer Ltd | Arts & recreation | 2026 |
| Bowl N Blast Ltd | Arts & recreation | 2026 |
| Bowlas Plumbing & Heating Supplies Limited | Wholesale & retail | 2025 |
| Bowman Court Management Co. Limited | Households | 1993 |
| Bowthorpe Limited | Extraterritorial | 1999 |
| BPD Trader Ltd | Information & communication | 2025 |
| BPN Consultancy Services Limited | Professional & scientific | 2018 |
| BPP Training Limited | Education | 2024 |
| BPS Offshore Services Limited | Professional & scientific | 1981 |
| Br-Trading UK Limited | Financial services | 1986 |
| Bradlaw House Dental Care Limited | Health & social care | 2010 |
| Brady Travel Limited | Transport & logistics | 2025 |
| Brain Worm Ltd | Information & communication | 2019 |
| Brainee Ltd | Information & communication | 2025 |
| Bramor Ltd | Real estate | 2025 |
| Bramson Ltd | Real estate | 2013 |
| Branas Investment Limited | Real estate | 2022 |
| Branding Box Ltd | Administrative & support | 2022 |
| Branque Ltd Ltd | Professional & scientific | 2025 |
| Brasa Butchers Ltd | Wholesale & retail | 2017 |
| Brasa Property Investment Ltd | Real estate | 2022 |
| Bravello Ltd | Wholesale & retail | 2025 |
| Brazier Consulting Limited | Professional & scientific | 2020 |
| Brazilian Bites Limited | Hospitality | 2026 |
| Breach Consultancy Limited | Professional & scientific | 2024 |
| Breath Health Consultancies Ltd | Health & social care | 2024 |