| Aviraj Services Ltd | Real estate | 2025 |
| Avol Investments Ltd | Real estate | 2024 |
| Aweside Developments Ltd | Real estate | 2009 |
| AWS Consulting Ltd | Professional & scientific | 2025 |
| Ayham British Innovators Limited | Information & communication | 2019 |
| Aylesford Court (Letchworth) Management Company Limited | Administrative & support | 2010 |
| Aylmerton Court Management Company Limited | Households | 1984 |
| Aztek Logistics Limited | Transport & logistics | 2003 |
| Aztek Self Storage Ltd | Extraterritorial | 2012 |
| Azureus Consulting Ltd | Information & communication | 2015 |
| B & D Construction Ltd | Construction | 2024 |
| B & E Homes Limited | Real estate | 2021 |
| BAD Bunnies Limited | Professional & scientific | 2020 |
| Badger-Gon Limited | Professional & scientific | 2018 |
| Baijan Consulting Ltd | Professional & scientific | 2019 |
| Bakker & Wilson Plumbing & Heating Ltd | Construction | 2013 |
| Bance Track Ltd | Professional & scientific | 2025 |
| Barbuci Services Ltd | Transport & logistics | 2026 |
| Bardell Design Ltd | Professional & scientific | 2026 |
| Barley Bourne Accountants Limited | Professional & scientific | 2023 |
| Barnet Metal & Engineering Co Limited | Wholesale & retail | 2006 |
| Barnet Woodhouse Limited | Extraterritorial | 2020 |
| Bars International Limited | Hospitality | 2001 |
| Barsham West Limited | Real estate | 2016 |
| Barton Capital Limited | Financial services | 2024 |
| Barton Jones Packaging Limited | Wholesale & retail | 1993 |
| Baruch Care Ltd | Health & social care | 2022 |
| Basra Enterprises Ltd | Wholesale & retail | 2010 |
| Basra Group Ltd | Real estate | 2015 |
| Basra Investments Ltd | Real estate | 2004 |
| Basra Office Limited | Real estate | 2025 |
| Battered Black Book Limited | Other services | 2016 |
| Battle Guide Tours Limited | Information & communication | 2020 |
| Bayridges Consulting Ltd | Transport & logistics | 2022 |
| BB Carpentry & Builders Ltd | Construction | 2024 |
| BB Ice Limited | Energy | 2024 |
| Bclr Limited | Professional & scientific | 2025 |
| BE Bold HOP Step Ltd | Education | 2024 |
| BE Living (Bromley North) Limited | Real estate | 2017 |
| BE Living Developments (Brunton) Limited | Real estate | 1999 |
| BE Living Developments (Chorley) Limited | Real estate | 1998 |
| BE Living Developments (Newton Aycliffe) Limited | Real estate | 2000 |
| BE Living Developments Limited | Real estate | 2001 |
| BE Living Group Limited | Construction | 2006 |
| BE Living Holdings Ltd | Construction | 2001 |
| BE Living Limited | Real estate | 2003 |
| Be:Here Holdings ANV Phase 4 Limited | Construction | 2024 |
| Be:Here Limited | Construction | 1995 |
| Beacon Care Services Limited | Administrative & support | 2014 |
| Bean Valley Coffee Ltd | Manufacturing | 2023 |
| Bearton Limited | Real estate | 2019 |
| Beauty BEE Academy Ltd | Other services | 2025 |
| Bedford Business Centre Limited | Real estate | 2023 |
| BEE Outside Ltd | Arts & recreation | 2024 |
| Beeby Anderson Recruitment Ltd | Administrative & support | 2006 |
| Beech Precision Engineering Limited | Manufacturing | 2002 |
| Being Mortal Community Interest Company | Health & social care | 2025 |
| Beka Holdings Ltd | Financial services | 2026 |
| Believe Global GEM Limited | Professional & scientific | 2024 |
| Belle and Beast Emporium Limited | Wholesale & retail | 2016 |
| Bellona Advisors Ltd | Professional & scientific | 2021 |
| BEN Coulter Electrical Ltd | Construction | 2017 |
| BEN Hubbard Ltd | Manufacturing | 2026 |
| Bench IT Limited | Administrative & support | 2013 |
| Benchmark Fabrications Group Limited | Financial services | 2022 |
| Benchmark Fabrications Limited | Manufacturing | 1994 |
| Benefit Care Limited | Health & social care | 2022 |
| Benson Injection Moulding Ltd | Manufacturing | 2025 |
| Beraha Limited | Education | 2026 |
| Berk and BRO Ltd | Energy | 2025 |
| Berkeley Road Holdings Limited | Real estate | 2023 |
| Berkhamsted Trading Company Limited | Extraterritorial | 1956 |
| Berts Autos Ltd | Wholesale & retail | 2025 |
| Best Before Café Community Interest Company | Hospitality | 2018 |
| Bevan Construction Limited | Construction | 2023 |
| Bevan Enterprises Ltd | Professional & scientific | 2023 |
| BHB Electrical and Construction Services Limited | Construction | 1999 |
| Bickerdikes Garden Centre Limited | Wholesale & retail | 1998 |
| Bidwell House Management Company Limited | Households | 1990 |
| Big Bart Ltd | Professional & scientific | 2026 |
| Big Geronimo Ltd | Transport & logistics | 2026 |
| Big Letters Little Letters Limited | Information & communication | 2019 |
| Biggleswade Investments Limited | Real estate | 2025 |
| Bikes of RYE Limited | Information & communication | 2024 |
| Billy Arnott Limited | Wholesale & retail | 2010 |
| Birchwood House Holdings Limited | Construction | 2022 |
| Bishopsgate Search Ltd | Administrative & support | 2020 |
| BJ Homes Limited | Real estate | 2011 |
| BL Precision Ltd | Manufacturing | 2000 |
| Black & Gold Consulting Ltd | Professional & scientific | 2024 |
| Black & White Automotive Ltd | Wholesale & retail | 2023 |
| Black Bull Properties Limited | Extraterritorial | 2012 |
| Black Wolf Post Ltd | Information & communication | 2023 |
| Blaxton Property Limited | Real estate | 2021 |
| Blaze Entertainment Limited | Information & communication | 2009 |
| Bloom DRH Limited | Real estate | 2021 |
| Blue Ambition Property Lettings UK Ltd | Real estate | 2021 |
| Blue JAY Oriental Foods Ltd | Wholesale & retail | 2011 |
| Blue Whale Plumbing and Heating Ltd | Construction | 2023 |
| Bluepeak Search & Consulting Limited | Administrative & support | 2023 |