| Bloomselfcare Ltd | Wholesale & retail | 2026 |
| Blossom Dale Management Company Limited | Households | 1987 |
| Blossom Flooring Co., Ltd | Extraterritorial | 2018 |
| Blossom Social Care Services Ltd | Health & social care | 2024 |
| Blossomify Community Interest Company | Education | 2024 |
| Blossomwell Care Recruitment Agency Ltd | Administrative & support | 2026 |
| Blost Technologies Limited | Administrative & support | 2025 |
| Blow Beauty (Kent) Limited | Other services | 2019 |
| Blow Hair (Chislehurst) Limited | Other services | 2019 |
| BLR Group Holdings Limited | Real estate | 2025 |
| BLT Italy Ltd | Manufacturing | 2025 |
| Blue and Gold Investments Ltd | Financial services | 2025 |
| Blue Ball Grantchester Ltd. | Hospitality | 2014 |
| Blue Butterfly Flooring Limited | Wholesale & retail | 2009 |
| Blue Chilli IT Ltd | Information & communication | 2021 |
| Blue Chilli Property Ltd | Real estate | 2020 |
| Blue Coral Solutions Limited | Professional & scientific | 2007 |
| Blue DOT Coaching Limited | Professional & scientific | 2016 |
| Blue Field Consulting Ltd | Information & communication | 2021 |
| Blue Flag Holdings Ltd | Administrative & support | 2017 |
| Blue Frog Software Limited | Professional & scientific | 2025 |
| Blue Frontier Engineering Limited | Professional & scientific | 2012 |
| Blue Green Ltd | Wholesale & retail | 2012 |
| Blue HAT Limited | Professional & scientific | 2007 |
| Blue Hawk Holdings Limited | Financial services | 2025 |
| Blue Homes UK Limited | Real estate | 2005 |
| Blue INK Architecture Limited | Professional & scientific | 2017 |
| Blue Line Operations Ltd | Administrative & support | 2014 |
| Blue Lion Limited | Other services | 1992 |
| Blue Monk Services Ltd | Administrative & support | 2020 |
| Blue Nugget Consulting Limited | Information & communication | 2018 |
| Blue Oaks Solutions Ltd | Manufacturing | 2020 |
| Blue Planet Electric Ltd | Wholesale & retail | 2024 |
| Blue Planet Import&Export Co., Ltd | Wholesale & retail | 2021 |
| Blue Ribbon BIO Limited | Professional & scientific | 2025 |
| Blue Sky Conversions Ltd | Extraterritorial | 2014 |
| Blue Smile Project | Health & social care | 2010 |
| Blue Sphere Health Limited | Professional & scientific | 2010 |
| Blue Stone Software Limited | Information & communication | 2024 |
| Blue Wings Marine Service Co., Ltd | Manufacturing | 2023 |
| Blue Yonder Events Ltd | Professional & scientific | 2013 |
| Blue Zephyr Ltd | Information & communication | 2015 |
| Blueaid Limited | Information & communication | 2007 |
| Bluebell Management (Aldershot) Limited | Households | 1998 |
| Bluebird (Chalgrove) LLP | | 2025 |
| Bluebird (Crow Lane) LLP | | 2025 |
| Bluebird (Ferndown) LLP | | 2026 |
| Bluebird Land Limited | Real estate | 2024 |
| Bluebird Media Ltd | Professional & scientific | 2025 |
| Bluebird Technology Limited | Information & communication | 2004 |
| Bluecat IP Limited | Financial services | 2021 |
| Bluefin Swim School Limited | Education | 2020 |
| Bluegrid Consultancy Ltd | Information & communication | 2025 |
| Bluehaven Global Ltd | Wholesale & retail | 2025 |
| Bluehouse Technology Limited | Information & communication | 2014 |
| Bluelightsdigital Ltd | Professional & scientific | 2015 |
| Bluemax Technology Support Ltd. | Construction | 2020 |
| Bluepeak Software Ltd | Information & communication | 2025 |
| Bluepoint Technologies Limited | Construction | 2008 |
| Blues Property Advisory Limited | Administrative & support | 2007 |
| Blues Property Construction Limited | Construction | 2017 |
| Blues Property FD Ltd | Construction | 2021 |
| Blues Property Fitzwilliam Limited | Real estate | 2022 |
| Blues Property Godesdone Ltd | Construction | 2021 |
| Blues Property Guilden Ltd | Construction | 2021 |
| Blues Property Hinton Avenue Ltd | Construction | 2021 |
| Blues Property Investments Ltd | Real estate | 2014 |
| Blues Property Kingston Ltd | Construction | 2021 |
| Blues Property Lettings Limited | Real estate | 2022 |
| Blues Property Limited | Construction | 2016 |
| Blues Property Over Ltd | Construction | 2021 |
| Blues Property Prsh Ltd | Construction | 2020 |
| Blues Property Sawston Ltd | Construction | 2020 |
| Blues Property Thriplow Ltd | Construction | 2025 |
| Blues Property Trumpington Limited | Construction | 2012 |
| Blues Property Warkworth Limited | Construction | 2022 |
| Bluescientific Limited | Professional & scientific | 2013 |
| Bluesky Cambridge Limited | Health & social care | 2021 |
| Bluesky Colors Ltd | Wholesale & retail | 2022 |
| Bluesky Resource Ltd | Professional & scientific | 2019 |
| Bluestone Capital Management Limited | Financial services | 2016 |
| Bluestone Investment Holdings Limited | Financial services | 2013 |
| Blundell Bioscience Rushmoor Limited | Professional & scientific | 2016 |
| Blusky Cleaning Solutions Ltd | Administrative & support | 2026 |
| Bluues Ltd | Administrative & support | 2024 |
| BLW Recruitment Ltd | Administrative & support | 2021 |
| Blythe Valley (Parcel S Apartments) Residents Management Company Limited | Households | 2021 |
| Blythewood Properties Limited | Real estate | 2000 |
| BMC Consultancy Services Limited | Professional & scientific | 2015 |
| BMG (British Medical Group) Limited | Financial services | 2020 |
| BMJ Motors Limited | Wholesale & retail | 2025 |
| Bmkk | Financial services | 2019 |
| BMR AI Solutions Ltd | Information & communication | 2026 |
| BMZ Innovation Group Ltd | Wholesale & retail | 2020 |
| BN Algorithms Limited | Information & communication | 2008 |
| BNB Asset Holdings Limited | Real estate | 2024 |
| BNC Aviation Services Ltd | Manufacturing | 2025 |
| Bnfm Ltd | Administrative & support | 2023 |
| BNK Holdco Limited | Financial services | 2025 |
| BO Digital Ltd | Professional & scientific | 2021 |