| BLH Holdings Limited | Financial services | 2023 |
| Bligh Financial Management Ltd | Financial services | 2002 |
| BLINDS2FIT Solutions Limited | Construction | 2020 |
| Bliss Cleaning Services Ltd | Administrative & support | 2025 |
| Blissful Cake Haven Limited | Manufacturing | 2025 |
| Blissfulkind Ltd | Wholesale & retail | 2023 |
| Blitz & Co Ltd | Administrative & support | 2013 |
| Block Accountants Limited | Professional & scientific | 2016 |
| Block Creative Property Limited | Real estate | 2019 |
| Blockbuild.Co.Uk Ltd | Construction | 2019 |
| Blockchain Enterprises Services Ltd | Information & communication | 2023 |
| Blockchain Management Limited | Financial services | 2025 |
| Blogg's Group Ltd | Financial services | 2026 |
| Bloggs Underground Services Ltd | Water & waste | 2026 |
| Bloodmoon FX Ltd | Arts & recreation | 2026 |
| Bloody Mary's Bar Ltd | Hospitality | 2026 |
| Bloom Beauty & Reflexology Ltd | Other services | 2025 |
| Bloom Support Services Ltd | Health & social care | 2026 |
| Bloomfoods Limited | Hospitality | 2021 |
| Blooming Gorse Ltd | Professional & scientific | 2026 |
| Bloomsbury Mill Ltd | Wholesale & retail | 2016 |
| Bloomsford Ltd | Other services | 2019 |
| Blossom & Broom Cleaning Company Ltd | Administrative & support | 2023 |
| Blossom Care for YOU Ltd | Health & social care | 2015 |
| Blossom Curry Ltd | Hospitality | 2024 |
| Blossom Dental Solutions Limited | Health & social care | 2024 |
| Blossom Path Care Limited | Public administration | 2025 |
| Blossom Valley Care Ltd | Transport & logistics | 2015 |
| Blou Consultancy Services Ltd | Professional & scientific | 2020 |
| Blox Poynt Ltd | Transport & logistics | 2025 |
| Blox Recruitment Ltd | Administrative & support | 2025 |
| BLT Ltd | Administrative & support | 2021 |
| BLU Bear Moto Ltd | Manufacturing | 2024 |
| Blue 7 Trading Ltd | Administrative & support | 2011 |
| Blue Aran Limited | Wholesale & retail | 1995 |
| Blue Bear Developments Limited | Construction | 2015 |
| Blue Birch Systems Limited | Information & communication | 2007 |
| Blue Bottle Leisure Ltd | Hospitality | 2008 |
| Blue Bubble Lettings Limited | Real estate | 2011 |
| Blue Cat Tattoo Studios Limited | Other services | 2026 |
| Blue Chip Golf Products UK Ltd | Wholesale & retail | 2025 |
| Blue Chip Marine Limited | Manufacturing | 2005 |
| Blue Compute Limited | Information & communication | 2012 |
| Blue Construct Ltd | Construction | 2021 |
| Blue Crest Marine Ltd | Manufacturing | 2024 |
| Blue Data Security Limited | Information & communication | 2014 |
| Blue Diamond Heating Services Limited | Construction | 2017 |
| Blue Dragon Combat Limited | Arts & recreation | 2015 |
| Blue Funnel (2005) Limited | Professional & scientific | 2005 |
| Blue Funnel Cruises Limited | Transport & logistics | 1993 |
| Blue GEE Supplies LLP | | 2012 |
| Blue Gravity Ltd | Hospitality | 2025 |
| Blue Harbour Estates Limited | Real estate | 2025 |
| Blue Heron Communications Limited | Professional & scientific | 2004 |
| Blue Hills 2011 Ltd | Real estate | 2011 |
| Blue JAY Ecology Limited | Professional & scientific | 2017 |
| Blue Level Media Limited | Information & communication | 1999 |
| Blue Marine Yachting Limited | Manufacturing | 2007 |
| Blue Motors Southampton Limited | Wholesale & retail | 2020 |
| Blue Mountain Inc Ltd | Wholesale & retail | 2024 |
| Blue Nile Holdings Ltd | Financial services | 2021 |
| Blue Ocean Monitoring Limited | Professional & scientific | 2015 |
| Blue ORB Advisory Ltd | Professional & scientific | 2026 |
| Blue Penguin Bars Ltd | Hospitality | 2023 |
| Blue Pirate Limited | Wholesale & retail | 2024 |
| Blue Racing Ltd | Transport & logistics | 2021 |
| Blue Ribbon Facilities Group Ltd | Administrative & support | 2017 |
| Blue Rock Systems Limited | Information & communication | 2005 |
| Blue Rocket Recruitment Limited | Administrative & support | 2020 |
| Blue Rocket Rental Limited | Real estate | 2022 |
| Blue Roof Bungalow Limited | Health & social care | 2016 |
| Blue Rose Cleaning Services Limited | Administrative & support | 2020 |
| Blue Rover Ltd | Professional & scientific | 2015 |
| Blue Sapphire Accounting Ltd | Professional & scientific | 2026 |
| Blue Sea Art Gallery Limited | Wholesale & retail | 2023 |
| Blue Sky Design & Build Limited | Administrative & support | 2012 |
| Blue Sky Developing (Carberry) Limited | Construction | 2023 |
| Blue Sky Developing Limited | Construction | 2015 |
| Blue Sky Windows (Hampshire) Limited | Construction | 2010 |
| Blue Spark Heating Ltd | Construction | 2017 |
| Blue Spring Healthcare Ltd | Administrative & support | 2016 |
| Blue Starlight Ltd | Administrative & support | 2016 |
| Blue Stone Financial Services Ltd | Financial services | 2023 |
| Blue Strand Marine Limited | Manufacturing | 2013 |
| Blue Survey Limited | Mining & quarrying | 2021 |
| Blue Tang Digital Ltd | Administrative & support | 2020 |
| Blue Willow Haven Caravans Ltd | Real estate | 2025 |
| Bluebell IT Consultancy Limited | Information & communication | 2016 |
| Bluebells Lettings Limited | Real estate | 2024 |
| Bluebox Software Solutions Ltd | Information & communication | 2019 |
| Bluecloud Photography Limited | Professional & scientific | 2011 |
| Bluedrop Services (Holdings) Limited | Financial services | 2019 |
| Bluedrop Services (NW) Limited | Financial services | 2010 |
| Bluejet Limited | Professional & scientific | 2005 |
| Blues Soul Tavern Limited | Hospitality | 2009 |
| Bluesand Limited | Construction | 1993 |
| Bluesea Relocations Ltd | Real estate | 2023 |
| Blueshift Manufacturing Limited | Professional & scientific | 2013 |
| Bluestratus Limited | Information & communication | 2012 |
| Blundell Flowers Ltd | Wholesale & retail | 2005 |