| Bites, Sips & ME Limited | Hospitality | 2026 |
| Bitgab Ltd | Transport & logistics | 2017 |
| Bixware Ltd | Information & communication | 2012 |
| Bixxi Trans Limited | Transport & logistics | 2023 |
| Bizsol Accountancy Ltd | Professional & scientific | 2026 |
| BJ OYE Consulting Limited | Professional & scientific | 2019 |
| Bj's Plaice Ltd | Hospitality | 2017 |
| BJS Plaice Private Ltd | Hospitality | 2021 |
| BK Mobile Services Ltd | Wholesale & retail | 2018 |
| BKA Delivery Services Ltd | Transport & logistics | 2018 |
| BKR Homes and Developments Limited | Construction | 2025 |
| Black & Bassu Trans Ltd | Transport & logistics | 2024 |
| Black & Bloom Limited | Hospitality | 2026 |
| Black Anchor Ltd | Real estate | 2025 |
| Black Bear IT Solutions Limited | Information & communication | 2013 |
| Black Box Controls Limited | Information & communication | 2005 |
| Black Box Property Ltd. | Real estate | 2011 |
| Black Bridge Property LPS Ltd | Real estate | 2023 |
| Black CAB Studio Ltd | Manufacturing | 2016 |
| Black Cat Property Solutions Ltd | Real estate | 2019 |
| Black Circle Apparel Limited | Wholesale & retail | 2022 |
| Black Electrical Ltd | Construction | 2019 |
| Black Harbour Ltd | Wholesale & retail | 2025 |
| Black Olive Food Ltd | Hospitality | 2024 |
| Black OPS Baits Ltd | Manufacturing | 2025 |
| Black Sail Red Sky Limited | Professional & scientific | 2019 |
| Black Star Property (Castilian ST) Ltd | Real estate | 2018 |
| Blackbear Fitness Limited | Wholesale & retail | 2021 |
| Blackberry Homecare Ltd | Health & social care | 2015 |
| Blackbird Consultancy Services Ltd | Professional & scientific | 2020 |
| Blackbird Property Management Ltd | Hospitality | 2014 |
| Blackpoint Media Ltd | Information & communication | 2016 |
| Blacksheep Windows Ltd | Construction | 2023 |
| Blacktrac Ltd | Administrative & support | 2010 |
| Blackwell Consulting Limited | Real estate | 2000 |
| Blade Architectural Glazing Limited | Construction | 2026 |
| Blade Bidco Limited | Financial services | 2025 |
| Blade Topco Limited | Financial services | 2025 |
| Blades & Geary Home Improvements Ltd | Construction | 2010 |
| Blake Electrical Installation Ltd | Construction | 2026 |
| Blake Property Services Holdings Ltd | Financial services | 2026 |
| Blaze Dental and Aesthetics Limited | Financial services | 2021 |
| Blazefield Tovey Limited | Real estate | 2005 |
| Blazing Trail Tours Limited | Administrative & support | 1999 |
| Bleach Properties Ltd | Administrative & support | 2018 |
| Bleak House Consultancy Limited | Information & communication | 2015 |
| Blenheim Property Group Ltd | Real estate | 2021 |
| Blenheim Sales & Lettings Ltd | Real estate | 2019 |
| Blessed Global Logistics Ltd | Transport & logistics | 2025 |
| Blinds in Harmony Limited | Wholesale & retail | 2007 |
| Bliss Suites Limited | Real estate | 2017 |
| Blisswood Limited | Wholesale & retail | 2021 |
| Blitz IT Cleaning Specialists Limited | Administrative & support | 2020 |
| BLK SHP Assets Ltd | Real estate | 2025 |
| BLOCK7 Limited | Information & communication | 2018 |
| Blockchain Logistics Ltd | Transport & logistics | 2019 |
| Blondies Bakes PB Ltd | Manufacturing | 2021 |
| BLOODS4YOU Ltd | Health & social care | 2023 |
| Bloom Business Coaching Ltd | Professional & scientific | 2023 |
| Bloom Software Ltd | Information & communication | 2023 |
| Bloomingfield Consulting Limited | Professional & scientific | 2024 |
| Bloompark (Rutland) Limited | Financial services | 2018 |
| Bloomwings Ltd | Wholesale & retail | 2025 |
| Blossom Bookkeeping Ltd | Professional & scientific | 2023 |
| Blounts Electrical Services Limited | Construction | 2019 |
| BLU Invest +UK Limited Partnership | | 2025 |
| BLU Invest MK Ltd | Real estate | 2025 |
| Blubell Hospitality Consultants Ltd | Professional & scientific | 2018 |
| Blue Arrow Property Management Ltd | Real estate | 2023 |
| Blue Bear Necessities Limited | Manufacturing | 2015 |
| Blue Blossom Developments Limited | Construction | 2017 |
| Blue Blossom Surveys Ltd | Professional & scientific | 2024 |
| Blue Creation Limited | Administrative & support | 2004 |
| Blue Crest Sports Ltd | Education | 2022 |
| Blue Diamond Coach Ltd | Other services | 2018 |
| Blue Diamond Wealth Ltd | Professional & scientific | 2024 |
| Blue Dolphin - Business Development Limited | Professional & scientific | 2007 |
| Blue Edge Consults Limited | Professional & scientific | 2025 |
| Blue Fire Studio Ltd | Professional & scientific | 2025 |
| Blue FOX Security Ltd | Administrative & support | 2024 |
| Blue FOX Transport Limited | Transport & logistics | 2005 |
| Blue Horizons Resorts (UK) Limited | Real estate | 2016 |
| Blue Horse Group Ltd | Hospitality | 2020 |
| Blue IVY Collection Ltd | Wholesale & retail | 2020 |
| Blue JAY Investments Limited | Real estate | 2020 |
| Blue Latern Trading Ltd | Other services | 2025 |
| Blue Line Trailers Limited | Professional & scientific | 2004 |
| Blue Magic Logistics Ltd | Transport & logistics | 2022 |
| Blue Magic Transport Ltd | Transport & logistics | 2019 |
| Blue Monkey Creative Limited | Information & communication | 2023 |
| Blue Ocean Strategies Limited | Wholesale & retail | 2026 |
| Blue Orange Production Limited | Professional & scientific | 2019 |
| Blue PAW Wellbeing and Trauma Support Limited | Health & social care | 2022 |
| Blue Ridge Global Operations Ltd | Wholesale & retail | 2025 |
| Blue Ridge Holdings Limited | Hospitality | 2016 |
| Blue Sky Blue Consultancy Limited | Real estate | 2005 |
| Blue Spider Consulting Limited | Information & communication | 2016 |
| Blue Tech Electrical Ltd | Construction | 2023 |
| Blue Tech Properties Ltd | Construction | 2023 |
| Blue Water Plumbing Services Limited | Construction | 2022 |