| Blue Oceans Property Consulting Ltd | Households | 2020 |
| Blue Octopus Learning Limited | Professional & scientific | 2026 |
| Blue Prior Developments Limited | Professional & scientific | 2003 |
| Blue Prior Securities Limited | Professional & scientific | 2000 |
| Blue Rabbit Chefs Ltd | Hospitality | 2023 |
| Blue Rose Garden Care Ltd | Administrative & support | 2025 |
| Blue Salamander Limited | Professional & scientific | 2021 |
| Blue Scaffolding Services Ltd | Construction | 2018 |
| Blue School Travel Ltd | Transport & logistics | 2023 |
| Blue Silver Solutions Ltd | Professional & scientific | 2019 |
| Blue Sky Arts Limited | Arts & recreation | 2001 |
| Blue Sky Films Ltd | Information & communication | 2022 |
| Blue Sky Outdoor Kitchens Ltd | Manufacturing | 2021 |
| Blue Sky South GOA Limited | Wholesale & retail | 2022 |
| Blue Star Couriers Ltd | Transport & logistics | 2025 |
| Blue Star Servis Ltd | Construction | 2025 |
| Blue Star Wings Limited | Administrative & support | 2019 |
| Blue Tile Property Consultants Ltd | Professional & scientific | 2011 |
| Blue Tyres Limited | Wholesale & retail | 2019 |
| Blue UP Ltd | Wholesale & retail | 2022 |
| Blue Veranda Seasons Ltd | Real estate | 2023 |
| Blue Water Web Design LLP | | 2003 |
| Blue Whale Property Limited | Real estate | 2020 |
| Bluebell (Reading) Limited | Hospitality | 2017 |
| Bluebell Chase Residents Management Company Limited | Households | 2017 |
| Bluebell Property Services Limited | Real estate | 2019 |
| Bluebells of Henley Limited | Extraterritorial | 2013 |
| Bluebells ST Limited | Real estate | 2015 |
| Blueberry Berkshire Ltd | Administrative & support | 2023 |
| Blueberry Media Digital Ltd | Professional & scientific | 2020 |
| Bluebird Accountancy Limited | Professional & scientific | 2017 |
| Bluebird Engineering Limited | Professional & scientific | 1985 |
| Bluecatchai Ltd | Information & communication | 2022 |
| Bluedawn Ltd | Professional & scientific | 2026 |
| Bluejay and Jack Summer Developments Ltd | Construction | 2019 |
| Bluejay Developments Limited | Real estate | 2014 |
| Bluejay Dogwellness Ltd | Agriculture & fishing | 2023 |
| Blueking Holdings Limited | Manufacturing | 2018 |
| Blueknight Limited | Administrative & support | 2025 |
| Bluekong Networks Limited | Information & communication | 2014 |
| Bluemango Technologies Limited | Information & communication | 2006 |
| Bluematchbox Potters Supplies Ltd | Wholesale & retail | 2021 |
| Blueorbit Trading Ltd | Wholesale & retail | 2025 |
| Blueprint Base Limited | Professional & scientific | 2026 |
| Blueprint Construction Reading Limited | Construction | 2025 |
| Bluerange Properties Ltd | Real estate | 2025 |
| Blueroot Technology Services Ltd | Information & communication | 2021 |
| Bluesat Limited | Information & communication | 2012 |
| Bluesky Financial Planners Limited | Financial services | 2019 |
| Bluesky Group World Ltd | Financial services | 2016 |
| Bluesky Independent Financial Advisers LLP | | 2011 |
| Bluesky Security and Cleaning Ltd | Administrative & support | 2026 |
| Blueskys Trading Limited | Wholesale & retail | 2015 |
| Bluesquare Repair Services Limited | Manufacturing | 2011 |
| Bluestar Software Limited | Information & communication | 1998 |
| Bluestone Financial Planning Limited | Financial services | 2021 |
| Bluestone Hemingway Ltd | Manufacturing | 2026 |
| Bluevision Consultancy Ltd | Information & communication | 2025 |
| Bluewater Marine Limited | Manufacturing | 2025 |
| Blueway Trading Limited | Wholesale & retail | 2024 |
| Blume Psychology Ltd | Health & social care | 2020 |
| Blunt Lines Ltd | Other services | 2024 |
| Blxck Mmxxi Limited | Wholesale & retail | 2021 |
| BM Kebab Ltd | Hospitality | 2023 |
| BM Providers Limited | Health & social care | 2019 |
| BMA Properties (UK) Limited | Real estate | 2011 |
| BMC Car Care Services Ltd | Other services | 2019 |
| BMC UK Subadvisor Support Limited | Financial services | 2016 |
| Bmc&C Limited | Wholesale & retail | 2020 |
| Bmcg Holdings Ltd | Financial services | 2026 |
| Bmep Ltd | Professional & scientific | 2024 |
| BMI Group Holdings UK Limited | Professional & scientific | 2016 |
| BMO Rail Ltd | Construction | 2016 |
| Bmoore Inventive Ltd | Professional & scientific | 2018 |
| BMS Mainline Limited | Wholesale & retail | 2012 |
| Bms(Silchester) Limited | Professional & scientific | 2003 |
| Bmsharley Ltd | Professional & scientific | 2019 |
| BN Process Solutions Limited | Professional & scientific | 2025 |
| BNB Squire Ltd | Real estate | 2026 |
| BND Property Limited | Real estate | 2019 |
| Bngsmart Ltd | Information & communication | 2025 |
| BNQ Plumbing & Heating Ltd | Construction | 2025 |
| BNW Technology Ltd | Information & communication | 2002 |
| BNW U.K. Ltd | Administrative & support | 2003 |
| Bo-Vision Limited | Information & communication | 2026 |
| Boast Site Services Ltd | Mining & quarrying | 2018 |
| Boat Holdings Limited | Financial services | 2025 |
| Boat Topco Limited | Financial services | 2025 |
| Boathouse Advisory Limited | Professional & scientific | 2025 |
| Boathouse Physiotherapy Limited | Health & social care | 2016 |
| BOB Cook Limited | Professional & scientific | 2013 |
| BOB Went Consulting Limited | Professional & scientific | 2015 |
| Bob's Properties Limited | Extraterritorial | 2004 |
| Boba Bloom Reading Ltd | Hospitality | 2023 |
| Bobo&Dida Ltd | Transport & logistics | 2025 |
| Bocata SUB Limited | Hospitality | 2021 |
| BOD Pubs Limited | Hospitality | 2026 |
| Bodea Beauty Ltd | Manufacturing | 2026 |
| Bodhi Technology Limited | Information & communication | 2019 |
| Bodie and Bloom Ltd | Manufacturing | 2025 |