| Bimla Private Limited | Real estate | 2022 |
| Bimwise Limited | Information & communication | 2025 |
| BIN Care Solutions Ltd | Administrative & support | 2025 |
| BIN Inza Limited | Wholesale & retail | 2026 |
| BIN Zahid Traders Limited | Wholesale & retail | 2025 |
| Binamic Digital Media Ltd | Information & communication | 2019 |
| Binamic Limited | Information & communication | 2002 |
| Binary Software Solutions Limited | Information & communication | 2023 |
| Bingham Road Ltd | Real estate | 2024 |
| Binishaz Aesthetics Ltd | Other services | 2021 |
| BIO Key Health Ltd | Health & social care | 2025 |
| Bio-Stasis Ltd | Wholesale & retail | 2023 |
| Biologics Ltd | Professional & scientific | 2024 |
| Biorow Ltd | Professional & scientific | 2009 |
| Bios Tech Limited | Information & communication | 2022 |
| Birama Limited | Health & social care | 2020 |
| Biramdas Constructions Limited | Construction | 2025 |
| Birch Sales & Marketing Limited | Wholesale & retail | 1984 |
| Birchway Holdings Ltd | Wholesale & retail | 2018 |
| Birdie Golf Carts UK Limited | Administrative & support | 2025 |
| Birk Accountancy Ltd. | Professional & scientific | 2023 |
| Birk Property Investments Ltd | Real estate | 2024 |
| Birk Software Ltd | Information & communication | 2018 |
| Birklands Estates Ltd | Real estate | 2021 |
| Birklean PPF Limited | Wholesale & retail | 2024 |
| Birmingham Grove Clinic Ltd | Health & social care | 2025 |
| Birnbeck Limited | Construction | 2015 |
| Biro Ltd | Real estate | 2024 |
| Birstall Foundry Company Limited | Manufacturing | 1959 |
| Biryani Nation Limited | Hospitality | 2024 |
| Biryaniiwala Limited | Hospitality | 2019 |
| Biryaniwala Group Ltd | Hospitality | 2020 |
| Biryaniwala Express Ltd | Hospitality | 2025 |
| Bisaj Ltd | Wholesale & retail | 2026 |
| Bishop Sports & Leisure Ltd. | Wholesale & retail | 1973 |
| Bishops Holdings Ltd | Extraterritorial | 2016 |
| Bismillah Halal Butcher & Groceries Ltd | Wholesale & retail | 2023 |
| Bismillah Private Limited | Information & communication | 2013 |
| Bison Logistics Ltd | Transport & logistics | 2021 |
| Biss Interiors London Ltd | Professional & scientific | 2026 |
| BIT2INFO Solutions Limited | Information & communication | 2016 |
| Bitnoa Ltd | Wholesale & retail | 2023 |
| Bitpointai Ltd | Financial services | 2018 |
| Bitss | Health & social care | 2025 |
| BIZ Estates Ltd | Real estate | 2025 |
| BIZ Glide Ltd | Wholesale & retail | 2022 |
| BIZ Mine Ltd | Professional & scientific | 2018 |
| BIZ Osprey Ltd | Wholesale & retail | 2018 |
| BIZ Support Professionals Ltd | Transport & logistics | 2013 |
| Bizbridge Ltd | Wholesale & retail | 2023 |
| Bizeq Limited | Professional & scientific | 1991 |
| Bizi Group Ltd | Transport & logistics | 2023 |
| Biznizkart Ltd | Wholesale & retail | 2022 |
| Bizz Services Limited | Transport & logistics | 2026 |
| Bizztastic Limited | Real estate | 2017 |
| Bizzy BEE Wash Ltd | Other services | 2023 |
| Bja's Subway Ltd | Hospitality | 2010 |
| Bjaj Innovations Ltd | Wholesale & retail | 2026 |
| Bjmh Group Limited | Transport & logistics | 2024 |
| BK Bargain Limited | Wholesale & retail | 2022 |
| BK Cars Ltd | Transport & logistics | 2010 |
| BK Holidays Limited | Administrative & support | 2022 |
| BK Leicester Limited | Hospitality | 2025 |
| BK Leytonstone Co Limited | Hospitality | 2025 |
| BK Property 1 Ltd | Real estate | 2026 |
| BK Sandhu Construction Ltd | Construction | 2021 |
| BK Slough Ltd | Hospitality | 2024 |
| BKD Dental Ltd | Health & social care | 2025 |
| BKE Immobilien-, Handels- & Dienstleistungs Ltd. | Real estate | 2005 |
| Bkhr Ltd | Wholesale & retail | 2022 |
| BKS Property Investments Limited | Real estate | 2019 |
| BKZ Contractors Ltd | Construction | 2019 |
| Black Ace Transport Ltd | Transport & logistics | 2022 |
| Black Arrow Automation Ltd | Information & communication | 2024 |
| Black Cone TM Ltd | Construction | 2026 |
| Black Fortress Security Services Ltd | Administrative & support | 2024 |
| Black Horse Design Limited | Wholesale & retail | 2025 |
| Black Horse Transport Ltd | Transport & logistics | 2025 |
| Black Knight London Chauffeurs Ltd | Transport & logistics | 2019 |
| Black Label Events Private Ltd | Hospitality | 2018 |
| Black Markhor Ltd | Professional & scientific | 2025 |
| Black Panther Consulting Ltd | Professional & scientific | 2018 |
| Black Panther Security Ltd | Administrative & support | 2022 |
| Black Pearl Consulting Ltd | Information & communication | 2009 |
| Black ROC Homes Holdings Ltd | Professional & scientific | 2024 |
| Black ROC Ltd | Administrative & support | 2023 |
| Black Roses Support C.I.C. | Hospitality | 2020 |
| Black Rosh Ltd | Financial services | 2024 |
| Black Wolf Transport Ltd | Transport & logistics | 2019 |
| Blackbeard Academy Ltd | Wholesale & retail | 2020 |
| Blackbeard Community Projects CIC | Arts & recreation | 2020 |
| Blackbolt Ltd | Agriculture & fishing | 2009 |
| Blackbrook Dorking Ltd | Real estate | 2025 |
| Blackbuck Travels Limited | Administrative & support | 2026 |
| Blackcrest Executive Car Ltd | Transport & logistics | 2026 |
| Blackfriars Dental Limited | Health & social care | 2021 |
| Blackpond Associates Limited | Professional & scientific | 2014 |
| Blackrock Asset Holdings Ltd | Real estate | 2025 |
| Blackrockk Ltd | Transport & logistics | 2016 |
| Blackstone Private Ltd | Construction | 2024 |