| Bizsol Ltd | Professional & scientific | 2014 |
| Biztech Supplies Ltd | Wholesale & retail | 2025 |
| BJ Private Hire Rental Ltd | Wholesale & retail | 2025 |
| Bjek Properties Ltd | Real estate | 2025 |
| BJG Transport Ltd | Transport & logistics | 2024 |
| BJK Consultancy Services Ltd | Professional & scientific | 2025 |
| BJN Constructions Ltd | Construction | 2024 |
| BJT Professional Services Limited | Administrative & support | 2012 |
| BK Moore Estates Ltd | Real estate | 2024 |
| BK Smart Repairs Ltd | Wholesale & retail | 2024 |
| BKC Holdings Limited | Professional & scientific | 2025 |
| BKH Catering Limited | Hospitality | 2023 |
| BKM Associates Limited | Professional & scientific | 2014 |
| BKM Builders Ltd | Construction | 2025 |
| BKW Consultants Ltd | Professional & scientific | 2025 |
| BL Brow Bar (Staffordshire) Limited | Other services | 2017 |
| Black AXE Industries Ltd | Hospitality | 2017 |
| Black Cabs (Stoke-On-Trent) Limited | Extraterritorial | 2008 |
| Black Cat IT Consulting Ltd | Information & communication | 2022 |
| Black Dog Industries Limited | Wholesale & retail | 2019 |
| Black Dog Technologies Limited | Professional & scientific | 2018 |
| Black Duck Ltd | Information & communication | 2023 |
| Black LAB Productions Limited | Other services | 2018 |
| Black Onyx Academy Limited | Education | 2022 |
| Black Onyx Concepts Ltd | Administrative & support | 2017 |
| Black Onyx Enforcement Services Limited | Administrative & support | 2023 |
| Black Onyx Holdings Limited | Financial services | 2020 |
| Black Onyx Maritime Limited | Administrative & support | 2021 |
| Black Onyx Network Limited | Administrative & support | 2023 |
| Black Pyramid Gaming LLP | | 2009 |
| Blackbird 1964 Limited | Extraterritorial | 2013 |
| Blackbird Construction Management Limited | Construction | 2024 |
| Blackbrook Developments Limited | Construction | 2003 |
| Blackburn Holdings Ltd | Financial services | 2022 |
| Blackburn Holiday Lets Ltd | Real estate | 2021 |
| Blackburn Rhys-Jones Developments Ltd | Real estate | 2020 |
| Blackgate Holdings North Ltd | Financial services | 2010 |
| Blackhatinvestments Limited | Real estate | 2019 |
| Blacklake Construction & Development Ltd | Construction | 2026 |
| Blacklake Leisure Lettings Limited | Real estate | 2011 |
| Blackpool Accommodations Limited | Hospitality | 2024 |
| Blackridge Equity Ltd | Real estate | 2025 |
| Blackton Grange Estates Limited | Hospitality | 2022 |
| Blackwood Finance Limited | Financial services | 2024 |
| Blanc Stone Ltd | Hospitality | 2023 |
| Blandie Ltd | Wholesale & retail | 2021 |
| Blatt Holdings Limited | Financial services | 2016 |
| Blazing K 9'S Ltd | Extraterritorial | 2023 |
| Blazing Marketing Limited | Extraterritorial | 2012 |
| Blbaz Convenience Store Ltd | Wholesale & retail | 2023 |
| BLG Family Office UK Limited | Professional & scientific | 2018 |
| Blinded Faith Limited | Health & social care | 2021 |
| Blinds 4 U Ltd | Wholesale & retail | 2014 |
| Blindsubuy Ltd | Wholesale & retail | 2020 |
| Blink and Smile Ltd | Health & social care | 2020 |
| Blink Digital Recruitment UK Limited | Administrative & support | 2020 |
| Blink Digital Services Limited | Administrative & support | 2020 |
| Blink Digital UK Limited | Information & communication | 2017 |
| Blink Socials Limited | Professional & scientific | 2025 |
| Blinkin-Ink & Mobis Ltd | Other services | 2014 |
| BLISSY97 Limited | Health & social care | 2026 |
| Blitz Fireworks Limited | Wholesale & retail | 2007 |
| Blitzworld Buggies Ltd | Manufacturing | 2015 |
| BLM Developments Ltd | Construction | 2026 |
| BLM Smiles Limited | Professional & scientific | 2018 |
| BLN Property Ltd | Real estate | 2025 |
| Block NW One Limited | Hospitality | 2018 |
| Blok Software Limited | Information & communication | 2025 |
| Blood Red Books Limited | Information & communication | 2013 |
| Bloodcare Ltd | Health & social care | 2026 |
| Bloody Good Employers Limited | Professional & scientific | 2021 |
| Bloody Good Period Ltd | Wholesale & retail | 2019 |
| Bloom & Gilded Ltd | Manufacturing | 2025 |
| Bloom Corporate Accounting Ltd | Professional & scientific | 2024 |
| Blooming Bump Limited | Health & social care | 2020 |
| Blooming Good Care Ltd | Public administration | 2021 |
| Bloor Capital Ltd | Information & communication | 2023 |
| Bloor Holdings NW Limited | Financial services | 2021 |
| Blossom Abode Ltd | Real estate | 2025 |
| Blossom Ladies Brunch CIC | Education | 2020 |
| Blossoms Midlands Ltd | Other services | 2026 |
| Bloxwich UK Limited | Hospitality | 2007 |
| Blubolt Security Limited | Extraterritorial | 2024 |
| Blubridge Holdings Ltd | Health & social care | 2024 |
| Blue Bay Hotels Limited | Administrative & support | 2019 |
| Blue Bay Travel Group Limited | Information & communication | 2017 |
| Blue Bay Travel Limited | Information & communication | 2005 |
| Blue Bell Hardingswood Ltd | Hospitality | 2026 |
| Blue Breeze Landscapes Ltd | Administrative & support | 2025 |
| Blue Chip Holdings Limited | Real estate | 2019 |
| Blue Chip Properties (Manchester) Limited | Real estate | 2003 |
| Blue CUB Property Limited | Real estate | 2021 |
| Blue Ribbon Media Ltd | Professional & scientific | 2023 |
| Blue River Networks Limited | Wholesale & retail | 2020 |
| Blue Sheep Media Ltd | Education | 2020 |
| Blue Tiffin Meir Limited | Hospitality | 2019 |
| Bluebean Consulting Ltd | Professional & scientific | 2005 |
| Bluebell (Crewe) Limited | Extraterritorial | 1987 |
| Bluebell Staffing Limited | Administrative & support | 2019 |
| Bluebell Stores Ltd | Wholesale & retail | 2019 |