| British Lion Screen Entertainment Limited | Information & communication | 1968 |
| British Lion Television Limited | Extraterritorial | 1991 |
| British South India Council of Commerce Limited | Other services | 2012 |
| Brittania Windows & Doors Ltd | Construction | 2025 |
| Brmste Ltd | Information & communication | 2023 |
| Brnd Fire Solutions Ltd | Public administration | 2024 |
| Brnd Labs Limited | Wholesale & retail | 2015 |
| Broadstone Carpentry Limited | Construction | 2013 |
| Broadsword Pest Control Limited | Extraterritorial | 2016 |
| Broadway Collective Ltd | Real estate | 2024 |
| Brockenhurst Property Services (East) Limited | Real estate | 2020 |
| Brockenhurst Property Services (West) Limited | Real estate | 2020 |
| Brockenhurst Property Services Limited | Real estate | 2008 |
| Brolen Holdings Limited | Financial services | 2018 |
| Brooker Mouldings Limited | Manufacturing | 1988 |
| Brookson (5458N) Limited | Administrative & support | 2007 |
| Broughton Hall Care Limited | Health & social care | 2014 |
| Broughton Property Company Ltd | Hospitality | 2019 |
| Browning Pest Services Ltd | Administrative & support | 2013 |
| Browninghill Ltd | Professional & scientific | 2019 |
| BRP Research Ltd | Households | 2025 |
| Bruce Wayne Limited | Information & communication | 2009 |
| Brumby Consulting Ltd | Information & communication | 2015 |
| Brunel Close and Dove Inn Residents Association Ltd | Water & waste | 2002 |
| Bruno Trans Ltd | Transport & logistics | 2015 |
| Brushworks Decorating Ltd | Construction | 2017 |
| Bruyant Data Ltd | Information & communication | 2026 |
| BS IT Consultants Limited | Professional & scientific | 2018 |
| BSK Projects Ltd | Mining & quarrying | 2026 |
| Bspm Property Limited | Hospitality | 2013 |
| Bsync IT Services Ltd | Information & communication | 2026 |
| BU Zora Limited | Education | 2019 |
| Buck Sidhu Ltd | Real estate | 2022 |
| Buckskin Evangelical Church | Other services | 2011 |
| Buhati Limited | Health & social care | 2021 |
| Build Budget Expert Ltd | Construction | 2024 |
| Build IT Development Limited | Construction | 2011 |
| Buildability Drives and Patios Ltd | Administrative & support | 2024 |
| Building Surveying and Project Management Limited | Professional & scientific | 2001 |
| Buildmaster Group Limited | Professional & scientific | 2025 |
| Bulk Water Tankers Ltd | Water & waste | 2020 |
| Bulldog Holdings Limited | Financial services | 1964 |
| Bulldog Mortlake Limited | Real estate | 2014 |
| Bumbitant Ltd | Wholesale & retail | 2022 |
| Bumble & BEE Jewellery Ltd | Manufacturing | 2021 |
| Bumblebee PA Executive Services Limited | Administrative & support | 2025 |
| Bunch and Bird Design Limited | Wholesale & retail | 2025 |
| Bunch's Market Garden Ltd | Agriculture & fishing | 2016 |
| Bunty Investments Ltd | Manufacturing | 2023 |
| Bureau Prive Limited | Real estate | 2023 |
| Burford Contracting Ltd | Manufacturing | 2015 |
| Burger Co Limited | Hospitality | 2026 |
| Burnham Lodge Holdings Limited | Professional & scientific | 2003 |
| Burnham Lodge Limited | Health & social care | 2003 |
| Burrowfields (Basingstoke) Management Limited | Administrative & support | 2006 |
| Busbar Installation Training Solutions Limited | Education | 2023 |
| Bushe Ltd | Wholesale & retail | 2021 |
| Business Consultancy Europe Ltd | Professional & scientific | 2022 |
| Business Finance Partners Limited | Financial services | 2010 |
| Business Services (RMD) Ltd | Professional & scientific | 2014 |
| Busy BEE Cleaning Basingstoke Limited | Extraterritorial | 2025 |
| Busy BEE Cleaning Hampshire Limited | Administrative & support | 2025 |
| Busy BEE Quality Carpet and Upholstery Cleaning Ltd | Administrative & support | 2008 |
| Butler & Butler Trading Limited | Wholesale & retail | 2008 |
| Butler J Limited | Wholesale & retail | 2016 |
| Buttermere Farms Limited | Agriculture & fishing | 2013 |
| Buttons & Bubbles C.I.C. | Wholesale & retail | 2023 |
| Buy IT for Life Ltd | Information & communication | 2021 |
| Buyer's Lounge Ltd | Wholesale & retail | 2022 |
| BV Readers Limited | Administrative & support | 2014 |
| Bwcb Community Interest Company | Arts & recreation | 2026 |
| BWS Engineering Limited | Professional & scientific | 2015 |
| Bymee Events Ltd | Hospitality | 2018 |
| Byron Lewis Ltd | Wholesale & retail | 2025 |
| Bytebridge Consulting Ltd | Information & communication | 2024 |
| Bébé Nurture Ltd | Health & social care | 2022 |
| C & B Autobody Repairs Ltd | Administrative & support | 2012 |
| C & D Plumbing and Heating Limited | Construction | 2016 |
| C & P James Services Limited | Professional & scientific | 2022 |
| C Hart Contractors Ltd | Construction | 2020 |
| C Harvey Limited | Construction | 2009 |
| C M Construction (UK) Limited | Construction | 2005 |
| C R Syklemoore & Sons | | 2001 |
| C S B Props Limited | Arts & recreation | 2022 |
| C&A Transports Limited | Transport & logistics | 2019 |
| C&E Manhattan Limited | Information & communication | 2017 |
| C&J Pet Services Ltd | Other services | 2019 |
| C&S Landscaping Ltd | Transport & logistics | 2019 |
| C&T Building Services Limited | Construction | 2005 |
| C-T Aviation Solutions Limited | Professional & scientific | 2006 |
| C-Tas Holdings Ltd | Professional & scientific | 2026 |
| C. I. Hants Prop Limited | Real estate | 2016 |
| C.S.I. Printing Ltd | Manufacturing | 2024 |
| C.Y. Construction Limited | Construction | 1999 |
| C.Y. Developments Limited | Construction | 2003 |
| C47 Limited | Information & communication | 2013 |
| CA Ecology Ltd | Professional & scientific | 2014 |
| CA Environmental Sustainable Solutions Consultancy Ltd | Professional & scientific | 2020 |
| Cable Products Limited | Extraterritorial | 1991 |
| Cadiva Holdings UK Limited | Financial services | 2022 |