| Blue Light Performance Limited | Professional & scientific | 2024 |
| Blue Lions FC Limited | Information & communication | 2020 |
| Blue Pink Management Ltd | Real estate | 2026 |
| Blue Rain Store Limited | Wholesale & retail | 2025 |
| Blue Sky Friday Ltd | Wholesale & retail | 2021 |
| Blue Sonic Limited | Construction | 2004 |
| Bluebell Bushcraft Ltd | Education | 2025 |
| Bluebell Spring Consultancy Limited | Professional & scientific | 2019 |
| Bluecrest Health Screening Limited | Health & social care | 2012 |
| Bluedoor UK Limited | Financial services | 2024 |
| Bluefinch Commerce Limited | Information & communication | 2025 |
| Blueocean Fish & Chips Ltd | Hospitality | 2018 |
| Bluepotato Ltd | Information & communication | 2016 |
| Bluestocking Consulting Ltd | Professional & scientific | 2022 |
| Bluestone B2B Limited | Administrative & support | 2012 |
| Blunova Limited | Administrative & support | 2014 |
| Blyko Limited | Professional & scientific | 2004 |
| Blyth Development Group Limited | Construction | 2025 |
| BN Chippy Limited | Hospitality | 2025 |
| BN Distribution Services Ltd | Wholesale & retail | 2026 |
| BN Fortune Limited | Hospitality | 2026 |
| BN Property Consultants Ltd | Professional & scientific | 2019 |
| BN Roofing and Guttering Ltd | Construction | 2026 |
| BN14 Art Studios Ltd | Arts & recreation | 2017 |
| BNF Global Ltd | Construction | 2025 |
| Bnweb Ltd | Information & communication | 2024 |
| Boards and Branding Ltd | Wholesale & retail | 2020 |
| BOB Mitchell Surveying Ltd | Other services | 2020 |
| Boden Beach Huts Limited | Hospitality | 2024 |
| Boden Solutions Limited | Wholesale & retail | 2024 |
| Bodimans Financial Unlimited | Financial services | 2025 |
| Bodimans LLP | | 2025 |
| Bodyfit Physiotherapy Limited | Health & social care | 2010 |
| Bodyworks Studio Ltd | Arts & recreation | 2012 |
| Bognor Pies Limited | Wholesale & retail | 2015 |
| BOH Global Holdings Limited | Real estate | 2023 |
| Boilerandplumbing.Com Ltd | Wholesale & retail | 2024 |
| Bold Growth Media Ltd | Information & communication | 2022 |
| Bold Wise Ltd | Professional & scientific | 2016 |
| Boldbakers Limited | Administrative & support | 2026 |
| Boldoak Partners Limited | Financial services | 2024 |
| Boldoak Services Limited | Professional & scientific | 2024 |
| Bollywood Spice Ltd | Hospitality | 2025 |
| BON Vivant Ltd | Hospitality | 2019 |
| Bongomad Ltd | Wholesale & retail | 2021 |
| Bookers Vineyard Ltd | Real estate | 2015 |
| Bookingthesea Ltd | Administrative & support | 2017 |
| Bookkeeping Spreadsheet Solutions Ltd | Hospitality | 2014 |
| Boormans Accountants Ltd | Professional & scientific | 2023 |
| Bora Aesthetic Ltd | Health & social care | 2019 |
| Borbely Property Services Limited | Construction | 2013 |
| Borderstock Limited | Real estate | 1997 |
| Borngrade Ltd | Construction | 2010 |
| Bosgo Ltd | Other services | 2017 |
| Boss Studio Ltd | Professional & scientific | 2021 |
| Boswell Park Homes Limited | Hospitality | 2018 |
| Bottle & JUG Dept. Ltd | Wholesale & retail | 2023 |
| Bottomline Accounts Ltd | Professional & scientific | 2014 |
| BOU Jewellery Ltd | Manufacturing | 2021 |
| Boudicca Proxy Ltd | Professional & scientific | 2011 |
| Boulevard Landscapes Ltd | Administrative & support | 2001 |
| Bounce and Play Surrey Limited | Administrative & support | 2024 |
| Bourke & Cooper Limited | Construction | 2001 |
| Bousham Ltd | Other services | 2021 |
| Boutique Editions Limited | Information & communication | 2003 |
| Boutique Management Consulting Ltd | Professional & scientific | 2025 |
| Bowden Chemicals Limited | Wholesale & retail | 1984 |
| Bowen Builders Limited | Construction | 2013 |
| Bower Interior Design Ltd | Professional & scientific | 2022 |
| Bowers & Wilkins Ltd | Manufacturing | 2025 |
| Bowman Books Ltd | Wholesale & retail | 2025 |
| Bowser Socials Ltd | Information & communication | 2023 |
| Bowsprit Holdings Limited | Real estate | 1990 |
| Bowsprit Property Development Limited | Construction | 1989 |
| Box Clever Music Limited | Arts & recreation | 2002 |
| Box Nails Ltd | Other services | 2018 |
| Boxco Limited | Manufacturing | 2025 |
| Boxfund 2 Limited | Wholesale & retail | 2014 |
| Boxfund Advisers Ltd | Professional & scientific | 2023 |
| Boxfund Limited | Financial services | 2022 |
| Boyd Family Properties Limited | Real estate | 2016 |
| Boyd Hotel Consultancy Services Ltd | Professional & scientific | 2025 |
| Boyle Properties Limited | Other services | 2005 |
| BP Executive Search Limited | Administrative & support | 2022 |
| BP Social Ltd | Information & communication | 2023 |
| Bpcauk Ltd | Professional & scientific | 2020 |
| BPM Training & Medical Services Limited | Education | 2023 |
| Bradley and Garnett Roofing and Construction Limited | Real estate | 2003 |
| Bradley and Lacy Ltd | Real estate | 2002 |
| Bradshire Investments Ltd | Real estate | 2020 |
| Braeside Estates Limited | Real estate | 2002 |
| Bragatha Ltd | Financial services | 2023 |
| Bramblestone Holdings Limited | Financial services | 2026 |
| Bramley & Sage Holdings Limited | Financial services | 2024 |
| Branch Baby Loss Network CIC | Education | 2024 |
| Branch Innovations Ltd | Education | 2026 |
| Brand Acceleration UK Limited | Administrative & support | 2023 |
| Brand Creative UK Limited | Professional & scientific | 2025 |
| Brand Mentors Marketing Media Ltd | Information & communication | 2026 |
| Brand Stand Limited | Manufacturing | 2011 |