| Blakespool Park Management Company Limited | Households | 1988 |
| Blakeyglobal Ltd | Professional & scientific | 2021 |
| Blamire Studio Limited | Wholesale & retail | 2021 |
| Blanch House Limited | Hospitality | 2010 |
| Blancke Medical Consultancy Limited | Health & social care | 2012 |
| Blanco Services Ltd | Health & social care | 2023 |
| Blandfield Properties Limited | Real estate | 2002 |
| Blank City Publishings Ltd | Information & communication | 2019 |
| Blank Thread Source Limited | Wholesale & retail | 2019 |
| Blank Vintage Ltd | Wholesale & retail | 2021 |
| Blast Event Hire Ltd | Hospitality | 2012 |
| Blast Events (Bristol) Limited | Hospitality | 2012 |
| Blast Fitness Health and Wellbeing Limited | Arts & recreation | 2022 |
| Blast Scaffolding Ltd | Construction | 2026 |
| Blastmaster (UK) Limited | Construction | 1998 |
| Blastnet Communications Limited | Information & communication | 2008 |
| Blatchford Solutions Limited | Financial services | 2024 |
| Blawz Ltd | Information & communication | 2025 |
| Blaxtar Productions Limited | Information & communication | 2008 |
| Blaxter Forse Limited | Real estate | 2021 |
| Blaze Studio Ltd | Arts & recreation | 2003 |
| Blazin Trowels Limited | Construction | 2004 |
| Blazing Holdings Limited | Hospitality | 2021 |
| Blazon Publishing & Media Limited | Information & communication | 2010 |
| BLC Construction Supplies Ltd | Administrative & support | 2011 |
| Bldg Construction Ltd | Construction | 2021 |
| Blding Ltd | Extraterritorial | 2019 |
| BLE Tools Ltd | Wholesale & retail | 2025 |
| Blencathra Nominees Limited | Extraterritorial | 2009 |
| Blend Group Holdings Limited | Financial services | 2024 |
| Blend Investments Limited | Real estate | 2024 |
| Blended Beginnings Ltd | Extraterritorial | 2023 |
| Blended Seven Limited | Information & communication | 2013 |
| Blendiq Limited | Information & communication | 2025 |
| Blenheim Brickwork Limited | Construction | 2006 |
| Blenheim Court (Winchcombe) Limited | Households | 2002 |
| Blenheim Road Flats Limited | Professional & scientific | 1964 |
| Blenheim Veterinary Centre Limited | Extraterritorial | 2008 |
| Blessed Indeed Childminder Ltd | Health & social care | 2023 |
| Blessings in Action CIC | Education | 2024 |
| Blfcollectables Ltd | Wholesale & retail | 2026 |
| Blinatech Ltd | Construction | 2026 |
| Blind Base Ltd | Wholesale & retail | 2019 |
| Blind Pictures Limited | Information & communication | 2012 |
| Blinds of Bath Limited | Other services | 2025 |
| Blindside Box Limited | Wholesale & retail | 2024 |
| Bling Consultancy Limited | Professional & scientific | 2022 |
| Blink Giant Media Ltd | Information & communication | 2008 |
| Blink of an EYE Studios Ltd | Professional & scientific | 2018 |
| Blink Plastering Ltd | Construction | 2024 |
| Blink Strategic Consulting Ltd. | Professional & scientific | 2018 |
| Blinkbox Autohaus Ltd | Transport & logistics | 2022 |
| Bliss Legal Limited | Professional & scientific | 2025 |
| Blissful Ventures Ltd | Real estate | 2024 |
| Blithe Yoga CIC | Education | 2025 |
| Blitx Fitness Ltd | Wholesale & retail | 2020 |
| Blitz Telemarketing Limited | Administrative & support | 1999 |
| Blj.Consultancy Ltd | Professional & scientific | 2019 |
| BLJ91A Ltd | Professional & scientific | 2023 |
| BLK Construction Ltd | Construction | 2023 |
| BLK Diamond Ltd | Wholesale & retail | 2025 |
| Blkamo Clothing Ltd | Wholesale & retail | 2024 |
| Blkwolf Motor Limited | Wholesale & retail | 2025 |
| Bloc Climbing Ltd | Arts & recreation | 2013 |
| Block 1 Cedar Hall (Management) Company Limited | Households | 1984 |
| Block 2 Cedar Hall (Management) Company Limited | Households | 1984 |
| Block 3 Cedar Hall (Management) Company Limited | Households | 1984 |
| Block 4 Cedar Hall (Management) Company Limited | Households | 1984 |
| Block Catering Ltd | Hospitality | 2025 |
| Blocked Drains Services Bristol Ltd | Construction | 2024 |
| Blockhaven Property Management Limited | Households | 1986 |
| Blockhouse Residents Company Limited | Households | 1989 |
| Blocktopus Limited | Information & communication | 2012 |
| Blocky Contractors Ltd | Construction | 2025 |
| Blog Write Ltd | Professional & scientific | 2019 |
| Bloggs Salons Ltd | Other services | 2010 |
| Blok Solutions Ltd | Administrative & support | 2002 |
| Bloke Group Ltd | Wholesale & retail | 2023 |
| Blokzero Management Ltd | Hospitality | 2017 |
| Blomonj Ltd. | Arts & recreation | 2021 |
| Bloodman Ltd | Health & social care | 2025 |
| Bloof Ltd | Wholesale & retail | 2026 |
| Bloom & Grow Studio Ltd | Professional & scientific | 2024 |
| Bloom & River Consulting Ltd | Professional & scientific | 2025 |
| Bloom Aesthetics & Spa Ltd | Wholesale & retail | 2022 |
| Bloom Mobile Beauty Limited | Professional & scientific | 2018 |
| Bloom PR & Communications Ltd | Professional & scientific | 2015 |
| Bloom Yoga Bristol Ltd | Other services | 2025 |
| Bloomfield Editorial Ltd | Information & communication | 2019 |
| Bloomsburg Limited | Professional & scientific | 2014 |
| Bloomsbury Bowling Limited | Arts & recreation | 2005 |
| Bloomsbury Leisure Holdings Limited | Professional & scientific | 2010 |
| Bloomsbury Management Ltd | Hospitality | 2019 |
| Bloop Player Ltd | Manufacturing | 2025 |
| Blossom 1 Solar Limited | Energy | 2020 |
| Blossom 2 Solar Limited | Energy | 2020 |
| Blossom Co Floral Design Limited | Wholesale & retail | 2020 |
| Blossom Green (Martley ) Management Company Limited | Households | 2025 |
| Blossoming Events Ltd | Administrative & support | 2023 |
| Blossoming Homes Ltd | Health & social care | 2009 |