| Blinksmile Ltd | Other services | 2025 |
| Blinman Ltd | Health & social care | 2016 |
| Bliqero Ltd | Wholesale & retail | 2026 |
| Blishee Ltd | Administrative & support | 2025 |
| Bliss Look Ltd | Wholesale & retail | 2021 |
| Blissett Care Ltd | Health & social care | 1999 |
| Blissfulnova Store Ltd | Wholesale & retail | 2025 |
| Blitz Recycling Limited | Water & waste | 2012 |
| Blitz Skips Limited | Water & waste | 2012 |
| Blitz Technologies Limited | Wholesale & retail | 2010 |
| BLJ Ltd | Information & communication | 2015 |
| BLM Consulting Ltd | Professional & scientific | 2018 |
| Bloc Coffee Ltd | Hospitality | 2017 |
| Bloc Construction Limited | Construction | 2018 |
| Bloc Draig Ltd | Information & communication | 2024 |
| Block a Lozelles Gardens RTM Company Limited | Households | 2024 |
| Block a Moorhead Close RTM Company Limited | Real estate | 2009 |
| Block B Moorhead Close RTM Company Limited | Real estate | 2009 |
| Block Feng Limited | Extraterritorial | 2021 |
| Block One Group Ltd | Professional & scientific | 2026 |
| Block Shengfeng Ltd | Wholesale & retail | 2021 |
| Blockbooster Ltd | Information & communication | 2025 |
| Blockbuster Films Ltd | Wholesale & retail | 2019 |
| Blockchain Data Group LP | | 2017 |
| Blockchain Innovation Ltd | Information & communication | 2017 |
| Blockchain Remittance Ltd | Information & communication | 2019 |
| Blockchain Tech Ltd | Information & communication | 2020 |
| Blockcraft Limited | Information & communication | 2025 |
| Blockex Limited | Information & communication | 2016 |
| Blockmoon Limited | Manufacturing | 2021 |
| Blockrank Limited | Information & communication | 2022 |
| Blockrock Ltd | Professional & scientific | 2020 |
| Blocksafevault Ltd | Information & communication | 2025 |
| Blocksports International Limited | Arts & recreation | 2022 |
| Blockup International Ltd | Manufacturing | 2025 |
| Blockup Ltd | Wholesale & retail | 2025 |
| Bloco Padel Ltd | Arts & recreation | 2026 |
| Bloemteknik Limited | Manufacturing | 2023 |
| Blogerops Ltd | Information & communication | 2024 |
| Blok Creative Ltd | Professional & scientific | 2025 |
| Blonde Properties Limited | Real estate | 2005 |
| Bloodline Planning Ltd. | Other services | 2019 |
| Bloodstream Digital Ltd | Information & communication | 2023 |
| Bloom BNB Ltd | Hospitality | 2025 |
| Bloom Street Limited | Real estate | 2020 |
| Bloom Workforce Solutions Ltd | Administrative & support | 2025 |
| Bloomberg Care Services Ltd | Health & social care | 2016 |
| Bloomboxclub Limited | Wholesale & retail | 2015 |
| Bloomery Group Ltd | Wholesale & retail | 2025 |
| Bloomhill Ltd | Manufacturing | 2022 |
| Blooming Good Limited | Professional & scientific | 2024 |
| Blooming Marvellous Staffing Agency Limited | Administrative & support | 2021 |
| Blooming Retail Ventures Ltd | Wholesale & retail | 2026 |
| Bloomingblossoms Ltd | Wholesale & retail | 2025 |
| Bloomistry Limited | Other services | 2009 |
| Bloomlayer IT Limited | Professional & scientific | 2025 |
| Bloomsberg Ltd | Other services | 2018 |
| Bloomsbury Trust Ltd | Financial services | 2025 |
| Bloomsbury Ventures Ltd | Financial services | 2025 |
| Bloomsway UK Ltd | Hospitality | 2025 |
| Blorem Limited | Wholesale & retail | 2021 |
| Blorvix Ltd | Education | 2025 |
| Blossom and Nectar Limited | Agriculture & fishing | 2019 |
| Blossom Connect Limited | Information & communication | 2025 |
| Blossom Creations Ltd | Construction | 2025 |
| Blossom Educational and Child Psychology Limited | Education | 2026 |
| Blossom Global Ltd | Extraterritorial | 2018 |
| Blossom Tree Nursery Rhiwbina Ltd | Education | 2016 |
| BLQ Ltd | Other services | 2026 |
| BLS Groundworks & Fencing Ltd | Administrative & support | 2019 |
| Bltim Limited | Administrative & support | 2018 |
| BLU Carpentry Ltd. | Manufacturing | 2017 |
| BLU Sky Enterprise Limited | Wholesale & retail | 2022 |
| BLU Vita Ltd | Administrative & support | 2025 |
| BLU2 Limited | Administrative & support | 2013 |
| BLU2 Tooth Fairy Limited | Health & social care | 2020 |
| Blue Aenvgiell Limited | Information & communication | 2021 |
| Blue Anchor Properties Limited | Real estate | 2023 |
| Blue Armour Ltd | Information & communication | 2015 |
| Blue Bear Temporary Talent Limited | Administrative & support | 2023 |
| Blue Beryl Services Ltd | Real estate | 2018 |
| Blue Box Investments Limited | Professional & scientific | 2003 |
| Blue Breeze Cleaning Limited | Administrative & support | 2018 |
| Blue Brush Ltd | Professional & scientific | 2021 |
| Blue Care Support Limited | Health & social care | 2025 |
| Blue Chip Corporate Chauffeurs Ltd | Transport & logistics | 2019 |
| Blue Cloud Hoster Ltd | Information & communication | 2022 |
| Blue Consulting (Cardiff) Limited | Hospitality | 2010 |
| Blue Crescent Investment and Trade Ltd | Wholesale & retail | 2025 |
| Blue Door Construction Ltd | Construction | 2025 |
| Blue Dreams Global Ltd | Wholesale & retail | 2025 |
| Blue Drop Laundry Ltd | Other services | 2026 |
| Blue Electrical Contractors Ltd | Construction | 2013 |
| Blue ELK Limited | Administrative & support | 2022 |
| Blue Flame (Cardiff) Ltd | Construction | 2015 |
| Blue Global X Ltd | Information & communication | 2025 |
| Blue Harper Corporation Limited | Information & communication | 2012 |
| Blue HAT Solutions Limited | Information & communication | 2010 |
| Blue Heavan Grills Limited | Hospitality | 2022 |
| Blue Horizon Energy Group Ltd. | Mining & quarrying | 2020 |