| Azulverde Travel & Tours (U.K.) Ltd | Administrative & support | 2023 |
| Azur Financial Ltd | Professional & scientific | 2014 |
| Azure Prism Limited | Wholesale & retail | 2016 |
| Azure Space Limited | Financial services | 2023 |
| Azzurro Group Limited | Manufacturing | 2023 |
| B & D Garden Service Ltd | Administrative & support | 2017 |
| B & D Property Investments Ltd | Real estate | 2022 |
| B & D Quantity Surveying Ltd | Professional & scientific | 2018 |
| B & G Property Management and Maintenance Limited | Real estate | 2026 |
| B & S Homes Ltd | Real estate | 2024 |
| B & S Hydraulics Limited | Professional & scientific | 1967 |
| B Broad Consultancy Ltd | Professional & scientific | 2026 |
| B Entertained Ltd | Information & communication | 2022 |
| B Financial Limited | Financial services | 2017 |
| B K Estate Holdings Ltd | Real estate | 2003 |
| B K Management Consultants Ltd | Financial services | 2016 |
| B Limani Ltd | Real estate | 2025 |
| B M Mortgages Ltd | Financial services | 2022 |
| B M Windows & Doors Limited | Construction | 2010 |
| B Milestone Limited | Health & social care | 2019 |
| B P Rabadiya Ltd | Construction | 2021 |
| B Sherwood Limited | Professional & scientific | 2010 |
| B X Bridal & Tailor Ltd | Wholesale & retail | 2022 |
| B X DRY Cleaners & Alterations Ltd | Administrative & support | 2015 |
| B&A Prime Cleaning Services Ltd | Administrative & support | 2026 |
| B&B Eco Ltd | Wholesale & retail | 2020 |
| B&B Quality Contractors Ltd | Construction | 2020 |
| B&C Retails Ltd | Hospitality | 2024 |
| B&Y.H Ltd | Wholesale & retail | 2025 |
| B-Fitt Fitness Ltd | Arts & recreation | 2013 |
| B-Tech Distribution Ltd | Information & communication | 2020 |
| B.B. Clarke (UK) Ltd | Manufacturing | 2000 |
| B.E.S.T. Medical Services Limited | Health & social care | 2006 |
| B.G Carpentry & Construction Ltd | Construction | 2026 |
| B.L Brown Ltd | Transport & logistics | 2025 |
| B.P. Sanders and Company Limited | Extraterritorial | 2022 |
| B.T.M. Print Limited | Manufacturing | 1997 |
| B2B Beauty Ltd | Other services | 2025 |
| B2C Glazing Limited | Construction | 2021 |
| BA Clinical Consultancy Ltd | Professional & scientific | 2013 |
| BA Global Ltd | Wholesale & retail | 2021 |
| BA London Investment Ltd | Real estate | 2022 |
| BAB Trans Ltd | Transport & logistics | 2019 |
| Baba Catering Watford Ltd | Hospitality | 2025 |
| Baba Yaga's HUT Ltd | Arts & recreation | 2025 |
| Babitha & Abraham Limited | Real estate | 2024 |
| Baby Cabaret CIC | Health & social care | 2023 |
| Baby Dragons Ltd | Wholesale & retail | 2009 |
| Baby Scan Clinic Limited | Health & social care | 2018 |
| Babze Ltd | Wholesale & retail | 2024 |
| BAC MAN Global Ltd | Wholesale & retail | 2024 |
| Back in Action Limited | Wholesale & retail | 1989 |
| Backyourdream Ltd | Wholesale & retail | 2022 |
| BAD Label Ltd | Manufacturing | 2022 |
| Bagata Ltd | Construction | 2016 |
| BAH Custom House Ltd | Construction | 2018 |
| Bahaar Design Ltd | Real estate | 2021 |
| Baheno Ltd | Real estate | 2025 |
| Bahra Designs Limited | Professional & scientific | 2005 |
| Bahubali Consultancy Services Limited | Information & communication | 2023 |
| Baigency Ltd | Wholesale & retail | 2025 |
| Bailey Enterprises Limited | Professional & scientific | 2019 |
| Bainbridge Consulting Limited | Information & communication | 2015 |
| Bains Financial Planning Limited | Financial services | 2019 |
| Bains Legal Ltd | Education | 2023 |
| Baja Ltd | Manufacturing | 2018 |
| Baked by Brooks Ltd | Wholesale & retail | 2025 |
| Baker Capital Holdings Limited | Financial services | 2019 |
| Baker Commercial Estates Limited | Real estate | 2001 |
| Baker Hills Management Ltd | Real estate | 2019 |
| Baker Plumbing and Heating Ltd | Construction | 2021 |
| Bakery Court (Bovingdon) Limited | Real estate | 2015 |
| Bakery Enache Limited | Manufacturing | 2020 |
| Baking Bread Ltd | Professional & scientific | 2020 |
| Bakk Property Management Limited | Households | 1988 |
| Balaji SAP Consulting Ltd | Professional & scientific | 2013 |
| Balance & Options Ltd | Arts & recreation | 2016 |
| Balctrans Limited | Transport & logistics | 2017 |
| Baldota Group Corporation Ltd | Hospitality | 2019 |
| Baldota Limited Liability Partnership | | 2023 |
| Baldwin & Bleakley Electrical Services Limited | Construction | 1976 |
| Balema Group Ltd | Wholesale & retail | 2020 |
| Balintore Gundogs Ltd | Administrative & support | 2025 |
| Balkan Consult Limited | Professional & scientific | 2017 |
| Balliee Buzz London Ltd | Wholesale & retail | 2023 |
| Balmoral Contracts Ltd | Construction | 2024 |
| Balshaw Metropole Limited Partnership | | 2002 |
| Balton CP Limited | Wholesale & retail | 1976 |
| Balton Technology Limited | Information & communication | 2022 |
| Balucci Properties Ltd | Real estate | 2017 |
| Balvane Ltd | Wholesale & retail | 2024 |
| Bama Capital Limited | Construction | 2020 |
| Bamblehorse Enterprises Limited | Information & communication | 2018 |
| Bamex UK Limited | Wholesale & retail | 2017 |
| Bamps Limited | Information & communication | 2000 |
| Banan Barber Ltd | Other services | 2025 |
| Banana Trading Ltd | Wholesale & retail | 2022 |
| Bananza Ltd | Wholesale & retail | 2020 |
| Bancil Partnership Limited | Other services | 1997 |
| Bancila Limited | Transport & logistics | 2023 |