| Bodge IT Limited | Wholesale & retail | 2008 |
| Bolch & Sipaul Limited | Health & social care | 2019 |
| Bolnore Limited | Households | 2009 |
| Bolnore Local Centre Management Company Limited | Real estate | 2006 |
| Bondeastleigh Limited | Professional & scientific | 2011 |
| Bonushouse Limited | Real estate | 2001 |
| Boodylara Ltd | Health & social care | 2023 |
| Books & Payroll Accounting Ltd | Administrative & support | 2011 |
| Boonified Ltd | Health & social care | 2021 |
| Borderless Digital Limited | Information & communication | 2020 |
| Borne Investments Limited | Administrative & support | 2002 |
| Borthong Ltd | Health & social care | 2019 |
| Bosphoressence Ltd | Wholesale & retail | 2006 |
| Boss Cooling Ltd | Construction | 2016 |
| BOT Geniuses Limited | Education | 2024 |
| Botlib.Ai Ltd | Information & communication | 2023 |
| Bourn Properties Ltd. | Real estate | 2015 |
| Bourne END & Henley Security Systems Limited | Administrative & support | 2009 |
| Boutique HR Partners Limited | Administrative & support | 2024 |
| Boyle & Summers Limited | Professional & scientific | 2014 |
| BP Protect Limited | Administrative & support | 2021 |
| Bprc Public Relations (Scott Crouch) Limited | Administrative & support | 2012 |
| BR 146 Flats Ltd | Real estate | 2017 |
| Bradbury Medico-Legal Services Ltd | Health & social care | 2018 |
| Bradford International College Limited | Education | 2021 |
| Bramble Equine Stud & Services Ltd | Agriculture & fishing | 2019 |
| Bramhal Ltd | Households | 2021 |
| Brands in Gaming Limited | Professional & scientific | 2003 |
| Branksome Care Limited | Health & social care | 2004 |
| Branta Talent Solutions Limited | Administrative & support | 2026 |
| Brave Army Design Ltd | Wholesale & retail | 2014 |
| Brenhaul Commercial (UK) Ltd | Wholesale & retail | 2013 |
| Breyer Group Public Limited Company | Construction | 1963 |
| Brian Nguyen Ltd | Wholesale & retail | 2021 |
| Bridge Beauty Limited | Other services | 2020 |
| Bridge Fire and Security Limited | Professional & scientific | 2012 |
| Bridge the GAP Travel Management Limited | Administrative & support | 2022 |
| Bright Culture Consulting Limited | Professional & scientific | 2025 |
| Brighter Minds Assessment Service Ltd | Health & social care | 2020 |
| Brightpath Consulting Limited | Professional & scientific | 2017 |
| Brightwire Electrical Ltd | Construction | 2013 |
| Brindley Technical Consultants Ltd | Professional & scientific | 2021 |
| Brise Properties Limited | Real estate | 2016 |
| Bristow Associates Group Holdings Ltd | Financial services | 2026 |
| British Teleflower Service Limited | Administrative & support | 1998 |
| Broadway Homeland Estates Limited | Real estate | 2019 |
| Brobrad Developments Limited | Administrative & support | 1997 |
| Brockton Homes Ltd | Real estate | 2016 |
| Broglia Press 86 Limited | Professional & scientific | 1980 |
| Broley Ltd | Construction | 2022 |
| Brompton Gardens (Ascot) Residents Management Company Limited | Households | 2018 |
| Brookeswood Developments Limited | Construction | 1993 |
| Brooklands Property Investments Ltd | Real estate | 2019 |
| Brookwood Management Company Limited | Real estate | 1990 |
| Brothers Awareness Emporium Ltd | Wholesale & retail | 2023 |
| Broughton Crafts Limited | Wholesale & retail | 2003 |
| Brow & Beauty (Chandlers Ford) Limited | Other services | 2019 |
| Brown & Green (Farm Shops) Limited | Wholesale & retail | 2010 |
| Browns Hair Lounge (Waltham Chase) Ltd | Other services | 2023 |
| Browns' Hair Lounge Limited | Other services | 2003 |
| Brownskin Limited Company Limited | Administrative & support | 2019 |
| Brows and Beauty Hampshire Limited | Other services | 2024 |
| Broxx Ltd | Wholesale & retail | 2017 |
| BRS Carpentry & Construction Ltd | Construction | 2014 |
| Brsj Consultancy Limited | Construction | 2016 |
| Bruce Pharm Limited | Health & social care | 2024 |
| Brunswick Company Secretaries Limited | Professional & scientific | 1998 |
| BTG Events Ltd | Hospitality | 2026 |
| Buba Real Estate Ltd | Real estate | 2025 |
| Bubble Property Group Ltd | Real estate | 2024 |
| Buchanan Freebird Limited | Extraterritorial | 1993 |
| Bucksmore Education Limited | Education | 1999 |
| Buffbay Limited | Other services | 2014 |
| Building Tech and Landscapes Ltd | Construction | 2024 |
| Buildtech Consultancy Ltd | Construction | 2018 |
| Bulletproof Guitar Player Ltd | Information & communication | 2024 |
| Bullfinch (2020) Limited | Real estate | 2019 |
| Bullshark Limited | Construction | 2004 |
| Bulwark Supported Living Ltd | Health & social care | 2024 |
| Bunce Logistics Ltd | Transport & logistics | 2026 |
| Bunkerman Limited | Administrative & support | 2000 |
| Bunnymans Ltd | Hospitality | 2026 |
| Burch Property Holdings Limited | Real estate | 2023 |
| Burchell's Consulting Limited | Professional & scientific | 2014 |
| Burnside Telecom Limited | Manufacturing | 2015 |
| Burton Mgmt Ltd | Professional & scientific | 2025 |
| Burton Property Limited | Construction | 2004 |
| Busimapiye Limited | Real estate | 2012 |
| Busineff Ltd | Information & communication | 2008 |
| Business Talent Growth (BTG) Ltd | Administrative & support | 2025 |
| Busy for Your Business Ltd | Administrative & support | 2024 |
| Butterflies Transportation Ltd | Transport & logistics | 2014 |
| Buyairo.Com Ltd | Wholesale & retail | 2025 |
| BY JO Crafts Limited | Wholesale & retail | 2021 |
| BY Pass Driver Training Ltd | Professional & scientific | 2016 |
| BY the Horns Ltd | Manufacturing | 2011 |
| Bzyproperties Ltd | Real estate | 2023 |
| C & C Conner Limited | Health & social care | 2006 |
| C & G Eastleigh Ltd | Other services | 2019 |
| C & G Regulatory Solutions Limited | Administrative & support | 2021 |