| BIO CNG Ltd | Energy | 2017 |
| BIO Construction Materials Ltd | Manufacturing | 2023 |
| Biorhythmic Synchrony Ltd | Health & social care | 2023 |
| Birchwood Sussex Limited | Professional & scientific | 2023 |
| Birds-I-Plm Limited | Information & communication | 2019 |
| Bishtec Race Engineering Ltd | Wholesale & retail | 2020 |
| BJN Roofing (Contractors) Limited | Construction | 1996 |
| BJN Roofing (Kent) Ltd | Construction | 2003 |
| BJN Roofing (Surrey) Ltd. | Construction | 2003 |
| BJN Roofing (Sussex) Ltd | Construction | 2003 |
| BJN Roofing Limited | Real estate | 1968 |
| Black Cat Commercial Services Limited | Wholesale & retail | 2011 |
| Black Desk Ltd | Hospitality | 2026 |
| Black Dog Charcoal Ltd | Agriculture & fishing | 2021 |
| Black Dog Firewood Limited | Agriculture & fishing | 2021 |
| Black Dog Forestry & Arboriculture Limited | Agriculture & fishing | 2021 |
| Black Dog Forestry Limited | Agriculture & fishing | 2018 |
| Black Isle (Europe) Holdings Ltd | Professional & scientific | 2019 |
| Black Isle (Europe) Limited | Professional & scientific | 2012 |
| Black Knight Developments Limited | Real estate | 1998 |
| Black Label Syndicate Limited | Financial services | 2020 |
| Blackburn & Emmett Limited | Real estate | 2020 |
| Blackfoxevents Ltd | Administrative & support | 2017 |
| Blackfriars Shipping Limited | Transport & logistics | 2020 |
| Blackgate Investments Ltd | Financial services | 2025 |
| Blackhouse Farm Maintenance Ltd | Administrative & support | 2025 |
| Blackhouse Farm Management (Sussex) Limited | Real estate | 2015 |
| Blades Cutting Edge Ltd | Other services | 2022 |
| Blairbeth Consulting Ltd | Financial services | 2011 |
| Blank Market Limited | Wholesale & retail | 2025 |
| Blikkaba Limited | Professional & scientific | 2017 |
| Blitzi Ltd | Information & communication | 2024 |
| Bloom Perfumery Ltd | Wholesale & retail | 2012 |
| Bloom Squared Ltd | Arts & recreation | 2021 |
| Blossom Floral Couture Limited | Wholesale & retail | 2022 |
| Bloxham Property Ltd | Real estate | 2023 |
| BLU Cyan Limited | Real estate | 2020 |
| Blue Apple Systems Limited | Information & communication | 2004 |
| Blue Capital Furniture Installation Ltd | Construction | 2018 |
| Blue Capital Holdings Ltd | Real estate | 2018 |
| Blue Capital Painting and Decoration Ltd | Construction | 2018 |
| Blue Capital Property Arrangement Consultant Ltd | Real estate | 2018 |
| Blue Fields Consulting Limited | Professional & scientific | 2016 |
| Blue Forge Ltd | Administrative & support | 2023 |
| Blue GAS & Heating Specialists Limited | Construction | 2016 |
| Blue Horizons Flight Training Ltd | Professional & scientific | 2021 |
| Blue Mountains Property Investments Limited | Real estate | 2016 |
| Blue Oak Trading & Investment Limited | Other services | 2004 |
| Blue Pear (Software) Limited | Information & communication | 2006 |
| Blue Shore Global Ltd | Professional & scientific | 2017 |
| Bluebells Day Nursery Ltd | Education | 1998 |
| Bluebrander Limited | Professional & scientific | 2018 |
| Blueco Estates Ltd | Construction | 2014 |
| Bluecoat Management Company Limited | Households | 2003 |
| Bluecoat Sports | Arts & recreation | 2002 |
| Bluehex Ltd | Information & communication | 2017 |
| Bluepeak Property Ltd | Real estate | 2026 |
| Blueschist Ltd | Real estate | 2026 |
| Bluewell Service Company Limited | Construction | 2024 |
| Blundell Holdings Limited | Other services | 2025 |
| BM Drivers Ltd | Transport & logistics | 2018 |
| BM Gates and Automation Ltd | Administrative & support | 2013 |
| BM Rental Cars - West Sussex Ltd | Administrative & support | 2026 |
| BM Roofing Sussex Limited | Construction | 2022 |
| BMC Energy Services Limited | Manufacturing | 2014 |
| BN3 Consulting Limited | Information & communication | 2020 |
| BNF Landscaping Ltd | Administrative & support | 2020 |
| Boardman, Gelly & Co. Ltd | Administrative & support | 2013 |
| BOB & Job's Property Ventures Ltd | Real estate | 2026 |
| BOB Barnett Limited | Professional & scientific | 2010 |
| BOB Leach Building & Project Management Limited | Construction | 2025 |
| Bobago Limited | Administrative & support | 2007 |
| BOC Golf Consulting Ltd | Professional & scientific | 2019 |
| Bodee Beauty Limited | Other services | 2018 |
| Bodywise Gym & Studios Limited | Arts & recreation | 2014 |
| Boiler Patrol Group Limited | Extraterritorial | 2023 |
| Boiler Technicians Limited | Construction | 2020 |
| Boka Holdings Limited | Professional & scientific | 2023 |
| Bold Star Marketing Limited | Professional & scientific | 2026 |
| Bonded Asset Corporation Limited | Other services | 2017 |
| Bondinvest Ltd | Professional & scientific | 2015 |
| Bookham Autos Ltd | Wholesale & retail | 2013 |
| Bookham Harrison Farms Limited | Manufacturing | 2007 |
| Borders & Boundaries Ltd | Administrative & support | 2025 |
| Born Free Trading Limited | Wholesale & retail | 1993 |
| Bosh Vending Ltd | Hospitality | 2025 |
| Boss Controls (North West) Ltd | Extraterritorial | 2020 |
| Boss Controls Group Limited | Financial services | 2020 |
| Boss Controls Ltd | Professional & scientific | 2010 |
| Boss Exclusive Limited | Arts & recreation | 2017 |
| Boston Road Development Limited | Construction | 2019 |
| Botanic Energy Limited | Professional & scientific | 2020 |
| Botonics Limited | Health & social care | 2007 |
| Boulder Consultants Ltd | Professional & scientific | 2026 |
| Boulderwood Ltd | Construction | 2024 |
| Boulter Construction Limited | Construction | 2022 |
| Boulter Mortgages Limited | Financial services | 2024 |
| Bound to Please Ltd | Manufacturing | 2023 |
| Boundless Works Ltd | Professional & scientific | 2025 |
| Bounty Lakes Ltd | Arts & recreation | 2025 |