| Beau Bespoke Limited | Financial services | 2021 |
| Beau Legal Limited | Professional & scientific | 2014 |
| Beckett House Limited | Education | 1993 |
| Bedi Partners Ltd | Construction | 2023 |
| BEE in a Tree Forest School Ltd | Education | 2023 |
| Beech Lawn Chalfont Ltd | Real estate | 2025 |
| Beechwood Place Care Ltd | Health & social care | 2014 |
| Beeson and Sons Limited | Construction | 1930 |
| Behr Medical Limited | Extraterritorial | 2013 |
| Belgravia Prime Ltd | Construction | 2025 |
| Bellair Hyperbarics Ltd | Extraterritorial | 2020 |
| Bellshaugh Limited | Financial services | 2014 |
| Beltane Construction Limited | Construction | 2020 |
| Belton Investments Limited | Real estate | 2009 |
| BEN More Management Company Limited | Households | 1987 |
| Benbrook Properties Limited | Real estate | 1978 |
| Benedict Newman Neri 7 Limited | Real estate | 2024 |
| Benifacts Umbrella Services Limited | Professional & scientific | 2014 |
| Benny Hancock Ltd | Wholesale & retail | 2019 |
| Beolite Services Ltd | Professional & scientific | 2020 |
| Bering Associates Ltd | Real estate | 2019 |
| Bering Ventures LLP | | 2023 |
| Berry Good Partnerships Ltd | Transport & logistics | 2020 |
| Berrycroft Management Company Limited | Administrative & support | 1985 |
| Bespique Limited | Wholesale & retail | 2026 |
| Bestoutcome Limited | Information & communication | 2000 |
| Better Homes (Surrey) Limited | Real estate | 2017 |
| Beverley Glock Limited | Professional & scientific | 2010 |
| Beyond Films Ltd | Information & communication | 2026 |
| Beyond Numbers Ltd | Professional & scientific | 2010 |
| Beyond Potential Limited | Other services | 2020 |
| Beyond the Gumline Ltd | Health & social care | 2014 |
| Beyond TNC (UK) Limited | Information & communication | 2020 |
| Bfbs | Information & communication | 1946 |
| Bfbs Aldershot Limited | Information & communication | 2013 |
| Bfbs Blandford Limited | Information & communication | 2013 |
| Bfbs Brize Norton Limited | Information & communication | 2015 |
| Bfbs Catterick Limited | Information & communication | 2013 |
| Bfbs Colchester Limited | Information & communication | 2013 |
| Bfbs Edinburgh Limited | Information & communication | 2013 |
| Bfbs Media Limited | Information & communication | 1998 |
| Bfbs Salisbury Plain Limited | Information & communication | 2013 |
| Bfbs Shorncliffe Limited | Information & communication | 2015 |
| BFG Capital Holdings Ltd | Financial services | 2025 |
| BFG Capital Ltd | Professional & scientific | 2025 |
| BG Bidco 3 Limited | Administrative & support | 2018 |
| BG Midco 3 Limited | Administrative & support | 2018 |
| BG Nominee 3 Limited | Administrative & support | 2018 |
| BG Topco 3 Limited | Administrative & support | 2018 |
| Bhatti Property Group Limited | Real estate | 2019 |
| Big Kahuna Management Limited | Arts & recreation | 2022 |
| Big MAC Productions Ltd | Construction | 2026 |
| Big Red Consulting Ltd | Professional & scientific | 2025 |
| Big Twin Limited | Wholesale & retail | 2010 |
| Bigsrigs Ltd | Construction | 2019 |
| Bigwood Portfolio Limited | Real estate | 2019 |
| Bika Developments Oak END Way Limited | Real estate | 2021 |
| Billaroo Limited | Construction | 2021 |
| Biocell Ltd | Professional & scientific | 2022 |
| Birchtrade Limited | Wholesale & retail | 1991 |
| Bird and Lovibond Limited | Professional & scientific | 2018 |
| Bird Design and Build Limited | Construction | 2025 |
| Bishop Simon Limited | Information & communication | 2018 |
| Bitcoin Properties Limited | Real estate | 2017 |
| Bizney Limited | Information & communication | 2019 |
| BJ Accounting Ltd | Professional & scientific | 2026 |
| BJC (Healthcare) Consulting Limited | Professional & scientific | 2008 |
| BJM Construction Ltd | Construction | 2018 |
| BJT Consulting Ltd | Professional & scientific | 2025 |
| BL Cleaning Ltd | Administrative & support | 2024 |
| BL Gardening Ltd | Administrative & support | 2024 |
| Blainey North Collection Limited | Administrative & support | 2015 |
| Blainey North Limited | Administrative & support | 2011 |
| Blantyre Link Limited | Wholesale & retail | 1990 |
| Blantyre Park Limited | Real estate | 2008 |
| Blantyre West Limited | Real estate | 2008 |
| Blast LOG Limited | Mining & quarrying | 2006 |
| BLG Ltd | Administrative & support | 2025 |
| Blix Ltd | Information & communication | 2019 |
| BLM Gardening Ltd | Administrative & support | 2025 |
| Blooming Magnolia Limited | Professional & scientific | 2018 |
| Blossom Gerrards Cross Ltd | Hospitality | 2021 |
| Blue Flame Boiler & Heating Repairs Ltd. | Construction | 1997 |
| Blue Green Health Ltd | Wholesale & retail | 2019 |
| Blue Iridium Limited | Professional & scientific | 2015 |
| Blue Lotus 360 Holdings Ltd | Information & communication | 2023 |
| Blue Moon Ventures Limited | Real estate | 2019 |
| Blue Penny Limited | Information & communication | 2003 |
| Blue Touch Paper Limited | Extraterritorial | 2007 |
| Blue Umbrella Group Limited | Real estate | 2017 |
| Bluebook Accountancy Ltd | Professional & scientific | 2013 |
| Bluecoat Investments Limited | Real estate | 1989 |
| Bluegrove Management Limited | Professional & scientific | 2011 |
| Bluevale Pristine Intelligence Limited | Professional & scientific | 2007 |
| BMD Advisory Limited | Professional & scientific | 2019 |
| Bmkd Universal Ltd | Financial services | 2023 |
| BMR Property Investment Company Limited | Real estate | 2019 |
| Boardfence Limited | Real estate | 1995 |
| Boatlamps Ltd | Wholesale & retail | 2011 |
| Bodisun Ltd | Other services | 2024 |