| Beyond Football Limited | Professional & scientific | 2023 |
| Beyond Inc Ltd | Information & communication | 2022 |
| BEZ Associates Ltd | Real estate | 2021 |
| Bezi Body Ltd | Construction | 2022 |
| BFA Construction Ltd | Construction | 2023 |
| BFP Services Kent Ltd | Other services | 2025 |
| Bfraysservices Limited | Health & social care | 2015 |
| BGF Ltd | Construction | 2018 |
| BH Hair & Tanning Ltd | Other services | 2024 |
| Bhathal Holdings Limited | Financial services | 2025 |
| Bhurji Limited | Other services | 2012 |
| BIA & KAR Limited | Transport & logistics | 2018 |
| Bicaconstruct Ltd | Construction | 2026 |
| Bicans Property and Maintenance Services Ltd | Construction | 2021 |
| Bicris Ltd | Transport & logistics | 2025 |
| Bidex Foods Ltd | Wholesale & retail | 2024 |
| Big 7 Express Ltd | Transport & logistics | 2020 |
| Big Arran's Ltd | Transport & logistics | 2016 |
| Big B Security Limited | Administrative & support | 2014 |
| Big Ledge Consulting Ltd | Administrative & support | 2025 |
| Big M Motor Spares Limited | Wholesale & retail | 1977 |
| Big Portion Perry Ltd | Hospitality | 2026 |
| Big Talk Consulting Ltd | Manufacturing | 2022 |
| Bigben Cinemas Ltd | Information & communication | 2015 |
| Bigu Construction Ltd | Construction | 2019 |
| Bigu Property Development Ltd | Real estate | 2022 |
| Bikesnbits Ltd | Other services | 2017 |
| Bilco Direct Ltd | Wholesale & retail | 2019 |
| Bill K Limited | Hospitality | 2023 |
| Billies Bakes Limited | Manufacturing | 2025 |
| Billington Travel Limited | Administrative & support | 2019 |
| Billy Interiors Ltd. | Construction | 2019 |
| Bilman Limited | Transport & logistics | 2010 |
| BIM MEP Ltd | Professional & scientific | 2021 |
| Bimsol Healthcare Ltd | Health & social care | 2025 |
| Binning Estates Ltd | Real estate | 2021 |
| Binostar Limited | Health & social care | 2025 |
| Bionicgpt Limited | Information & communication | 2023 |
| Birdi Healthcare UK Ltd | Health & social care | 2024 |
| Birth and Nature Ltd | Health & social care | 2019 |
| Bishop & Bishop Kent Ltd | Hospitality | 2025 |
| Bismillah Eatery Limited | Hospitality | 2018 |
| BIT Technologies (GB) Ltd | Information & communication | 2014 |
| Bizo Trans Ltd | Transport & logistics | 2021 |
| Bizone Ltd | Construction | 2015 |
| BJ Construction Services Ltd | Extraterritorial | 2015 |
| BJP Shopfitting Ltd | Construction | 2026 |
| BK Mechanical Management Ltd | Construction | 2023 |
| BL Prime Limited | Administrative & support | 2025 |
| Black Badger Systems Ltd | Professional & scientific | 2019 |
| Black Barn Property Management Limited | Real estate | 2026 |
| Black Diamonds Nexus CIC | Information & communication | 2025 |
| Black Eagle Academy International Limited | Administrative & support | 2026 |
| Black Eagle Academy Limited | Wholesale & retail | 2023 |
| Black Eagle Security Limited | Administrative & support | 2016 |
| Black Financial Services Limited | Financial services | 2014 |
| Black Mums Essex C.I.C. | Administrative & support | 2025 |
| Black Mums Kent C.I.C. | Administrative & support | 2024 |
| Black Mums Surrey Ltd | Administrative & support | 2025 |
| Black Oak Developments Ltd | Administrative & support | 2016 |
| Black Oak Joinery Ltd | Construction | 2018 |
| Black Turtle Group Limited | Other services | 2023 |
| Blackcurrant Limited | Real estate | 2017 |
| Blackheath Coffee Co Limited | Hospitality | 2025 |
| Blackout Evolution Ltd | Arts & recreation | 2024 |
| Blackstone Brothers Limited | Real estate | 2019 |
| Blackwells Jewellers Ltd | Manufacturing | 2018 |
| Blackwing Productions Ltd | Information & communication | 2016 |
| Blaggan Holdings Limited | Financial services | 2023 |
| Blanco Koncept Limited | Other services | 2017 |
| Blazon Fabrications Limited | Manufacturing | 1979 |
| Blazon Holdings Limited | Manufacturing | 2008 |
| Blessing Joy and Grace Limited | Construction | 2015 |
| Bleu Iris Technologies Ltd | Transport & logistics | 2021 |
| Blinkin Ltd | Wholesale & retail | 2016 |
| Blitz Force Ltd | Wholesale & retail | 2025 |
| BLJ Logistic Ltd | Construction | 2022 |
| Blmk Limited | Information & communication | 2005 |
| Blocktech Electrical Ltd | Construction | 2017 |
| Blocktech MEP Limited | Administrative & support | 2020 |
| Blonpek Global Concept Limited | Construction | 2019 |
| Bloomfield Sustainable Solutions Ltd | Administrative & support | 2019 |
| Bloomsbury Incorporated Limited | Health & social care | 1986 |
| Bloomville Integrated Systems Limited | Wholesale & retail | 2021 |
| Blossom Kids Childcare Limited | Health & social care | 2020 |
| BLT 1 Limited | Real estate | 2022 |
| BLU YNK Ltd | Other services | 2023 |
| Blucrete Cement Limited | Wholesale & retail | 2020 |
| Blue Abacus Consultancy Ltd | Administrative & support | 2025 |
| Blue Cube Connections Limited | Information & communication | 2007 |
| Blue Foam Ltd | Other services | 2019 |
| Blue Light Holidays Limited | Real estate | 2021 |
| Blue Logic Electrical Services Ltd | Construction | 2017 |
| Blue Ocean Futures Limited | Information & communication | 2021 |
| Blue Pearl Property Management Ltd | Real estate | 2023 |
| Blue Planet Bioresources Ltd | Professional & scientific | 2019 |
| Blue Sky International Finance Limited | Financial services | 2023 |
| Bluebell Barn Farm Ltd | Administrative & support | 2016 |
| Bluebriks Properties Ltd | Real estate | 2019 |
| Blueeyesconstruction Ltd | Construction | 2022 |