| BMV Group Ltd | Construction | 2024 |
| BNG Portal Limited | Information & communication | 2023 |
| BNS Screeding Limited | Construction | 2018 |
| BNW123 Holdings Limited | Administrative & support | 2023 |
| BNW123 Limited | Administrative & support | 2023 |
| BOB and Weave Salons Ltd | Other services | 2025 |
| Bobagee Limited | Hospitality | 2024 |
| Bobbya Ltd | Transport & logistics | 2025 |
| Bobbylewis Limited | Real estate | 2020 |
| Bodes Abodes Ltd | Real estate | 2026 |
| Bogdan Transport Ltd | Transport & logistics | 2021 |
| Boiler Care Services Ltd | Construction | 2026 |
| Bolivian and General TIN Trust PLC | Administrative & support | 1925 |
| Bond Residential Danbury Limited | Real estate | 2018 |
| Bond Residential Land and New Homes Limited | Real estate | 2015 |
| Bond Residential Limited | Real estate | 2009 |
| Boneyard Collars UK Ltd | Manufacturing | 2026 |
| Bonito Burrito Ltd | Hospitality | 2020 |
| Bonsack Ltd | Manufacturing | 2006 |
| Bonsai Investment Group Ltd | Real estate | 2026 |
| Boody UK Limited | Wholesale & retail | 2023 |
| Book a Builder UK Limited | Extraterritorial | 2022 |
| Book a Guard Security Services Ltd | Administrative & support | 2026 |
| Book for Care Limited | Information & communication | 2015 |
| Book for Fitness Limited | Information & communication | 2015 |
| Book for Health Limited | Information & communication | 2015 |
| Booth Financial Services Limited | Financial services | 2003 |
| Boothroyd Limited | Professional & scientific | 2007 |
| Bootyful Construction Limited | Construction | 2025 |
| Boreham Conservation Society | Other services | 2001 |
| Boreham Leisure Limited | Hospitality | 2011 |
| Borgh Drylining & Partitioning Ltd | Construction | 2015 |
| Boriste Ltd | Financial services | 2018 |
| Borita Transport Limited | Transport & logistics | 2018 |
| Borley Court Management Company Limited | Households | 1992 |
| Boss Electric Vehicle Chargers Ltd | Extraterritorial | 2020 |
| Boss Electric Vehicle Charging Ltd | Extraterritorial | 2020 |
| Boss Electric Vehicle Company Ltd | Extraterritorial | 2020 |
| Boss Hoggs Ltd | Hospitality | 2019 |
| Botany Bay Bungalow Limited | Real estate | 2020 |
| Botany Services Limited | Real estate | 2018 |
| BOTEV1913 Ltd | Construction | 2017 |
| Boulter, Hepburn and Watts Limited | Wholesale & retail | 2015 |
| Bourne High Performance Powertrains Ltd | Professional & scientific | 2019 |
| Bourne HPP Holdings Ltd | Financial services | 2024 |
| Bourne HPP Ltd | Professional & scientific | 2024 |
| Bourne Motorsport Engineering Ltd | Professional & scientific | 2022 |
| Bouttell Property Investment Limited | Real estate | 2019 |
| Bower Croft Limited | Real estate | 2018 |
| Bower Inc Ltd | Real estate | 2021 |
| Bowerbirds Interiors Limited | Wholesale & retail | 2017 |
| Bowl Bites Limited | Arts & recreation | 2025 |
| Bowler Estates Limited | Real estate | 2019 |
| Bowls Zone Limited | Wholesale & retail | 2026 |
| Box Golf Limited | Wholesale & retail | 2025 |
| Box Perfection Limited | Construction | 2019 |
| Box River Studios Limited | Information & communication | 2017 |
| Box Talent Limited | Professional & scientific | 2026 |
| Boxedbinary Limited | Information & communication | 2023 |
| Boyton Cross Garage Ltd | Wholesale & retail | 2025 |
| BPG UK Services Limited | Hospitality | 2026 |
| BPH Facilities Limited | Construction | 2011 |
| BPH Rail & Civil Engineering Limited | Construction | 2011 |
| Bptuning Ltd | Wholesale & retail | 2025 |
| BPW OIL, GAS & Drainage Services Ltd | Construction | 2022 |
| Brabourne (UK) Ltd | Real estate | 2012 |
| Brad Green Physiotherapy Ltd | Health & social care | 2024 |
| Brad Rogers Group Ltd | Construction | 2024 |
| Bradford Memorials Limited | Manufacturing | 2002 |
| Braemar Garages Management Company Limited | Households | 2013 |
| Bragg Central Limited | Information & communication | 1997 |
| Brainpal Ltd | Health & social care | 2025 |
| Braintree MOT Centre Ltd | Wholesale & retail | 2012 |
| Braintree Removals Ltd | Transport & logistics | 2008 |
| Braintree Van Hire Ltd | Administrative & support | 2017 |
| Brake Fit Mobile Limited | Wholesale & retail | 2018 |
| Brambles Lane Development Ltd | Construction | 2024 |
| Brambles of Bromeswell Ltd | Hospitality | 2020 |
| Bramling Developments Limited | Construction | 2018 |
| Bramptons Developments Ltd | Construction | 2022 |
| Bramptons Properties Limited | Construction | 2026 |
| Bramwoods Residents Association Limited | Households | 1976 |
| Brand and Howes Environmental Limited | Water & waste | 2006 |
| Brandify PR and Marketing Ltd | Professional & scientific | 2025 |
| Branding by Garden Limited | Administrative & support | 2010 |
| Brandon Residential Homes Ltd | Real estate | 2021 |
| Brandora Sales Group Ltd | Administrative & support | 2025 |
| Brands Network UK Limited | Wholesale & retail | 2025 |
| Branocs and City Wealth Limited | Financial services | 2026 |
| Brantwood Productions Limited | Information & communication | 2018 |
| Bratton Foods Ltd | Hospitality | 2020 |
| Breakaway Holidays and Weekends Limited | Administrative & support | 2002 |
| Breakdown Recovery Essex Ltd | Transport & logistics | 2025 |
| Breakthrough Health and Wellness Ltd | Health & social care | 2026 |
| Breakthrough HR Limited | Professional & scientific | 2017 |
| Brentwood Brothers Ltd | Other services | 2024 |
| Brentwood Communications Limited | Information & communication | 1978 |
| Brentwood Cycle Co.Limited | Real estate | 1948 |
| Brentwood Executive Cars Ltd | Transport & logistics | 2018 |
| Brentwood Leisure Park Limited | Real estate | 2025 |