| Basement Bond Limited | Manufacturing | 2025 |
| Basicbegin Limited | Agriculture & fishing | 1996 |
| Basil Brush Limited | Information & communication | 2013 |
| Basil Street Capital LLP | | 2013 |
| Basil Street Energy Limited | Wholesale & retail | 2018 |
| Batchelor Landscaping Ltd | Administrative & support | 2025 |
| Bath Zone Ltd | Wholesale & retail | 2007 |
| Bathroom Warehouse Winchester Ltd | Wholesale & retail | 2017 |
| Bathwick Tyres Limited | Extraterritorial | 1984 |
| Baticore Limited | Wholesale & retail | 2025 |
| Battered Sole Limited | Administrative & support | 2006 |
| Battery Realty Ltd | Real estate | 2022 |
| Baxter Environmental Limited | Administrative & support | 2017 |
| Baxter Heat Pumps Ltd | Professional & scientific | 2017 |
| Bayescamp Ltd. | Information & communication | 2017 |
| Bayit Home Community Interest Company | Real estate | 2023 |
| Bayview Property Management Ltd | Real estate | 2013 |
| BBK (Southampton) Ltd | Hospitality | 2020 |
| Bbre Limited | Real estate | 2025 |
| BC Challenge Limited | Administrative & support | 2015 |
| BCM (IOW) LLP | | 2011 |
| BCM Wilson Hill Limited | Real estate | 2023 |
| BDS Technology Limited | Administrative & support | 1999 |
| BE Green Cleaning Limited | Administrative & support | 2019 |
| Beachy Holdings Limited | Extraterritorial | 2004 |
| Beachy Limited | Administrative & support | 2004 |
| Beacon Business Healthcare Ltd | Other services | 2010 |
| Beacon Hill Office Limited | Professional & scientific | 2013 |
| Beacon Hill Producers Limited | Professional & scientific | 2007 |
| Beaconsfield Restaurants Limited | Hospitality | 2004 |
| Beadon Meadow Management Company Limited | Real estate | 2018 |
| Beam Design Limited | Construction | 1994 |
| Bear Construction South Ltd | Construction | 2019 |
| Beau Auto Services Ltd | Wholesale & retail | 2026 |
| Beau Education Ltd | Information & communication | 2026 |
| Beau Rentals Limited | Real estate | 2025 |
| Beauty in Sound Ltd | Wholesale & retail | 2021 |
| Bebesgrene Developments Limited | Construction | 1964 |
| BEC Hill Limited | Agriculture & fishing | 2023 |
| Becvar Health Limited | Health & social care | 2014 |
| Bedfield House Limited | Hospitality | 2009 |
| Bedrok Marketing Ltd | Professional & scientific | 2022 |
| BEE Content Ltd | Professional & scientific | 2025 |
| Beech Lawn Care Limited | Health & social care | 2003 |
| Beechcroft Farm (Winchester) LLP | | 2011 |
| Beeches Park NO.1 Residents Company Limited | Households | 1988 |
| Beef Farmers Direct Limited | Agriculture & fishing | 2009 |
| Beesanaes Limited | Health & social care | 2016 |
| Beest Limited | Professional & scientific | 2012 |
| Before the Box Ltd | Professional & scientific | 2014 |
| Belgarum Counsel Ltd | Professional & scientific | 2025 |
| Belgarum Estate Agents Limited | Real estate | 2004 |
| Bell Brickwork Ltd | Construction | 2014 |
| Bell Silencer Services Limited | Extraterritorial | 1977 |
| Bell-Fox Ltd | Administrative & support | 2004 |
| Bellacrafts Community CIC | Education | 2026 |
| Bellacrafts Limited | Wholesale & retail | 2010 |
| Bellamy Trustees Limited | Professional & scientific | 2018 |
| Bellevue Estates (Southampton) Limited | Hospitality | 1998 |
| Bells and Whistles Make Ltd | Manufacturing | 2018 |
| Belmont Advisory Limited | Professional & scientific | 2024 |
| Belmont Court Freehold Company Limited | Households | 2005 |
| Belrose Limited | Health & social care | 2011 |
| BEN Appleton Landscapes Ltd | Professional & scientific | 2020 |
| BEN White Smiles Ltd | Health & social care | 2016 |
| Ben's Pilates Ltd | Arts & recreation | 2022 |
| Benivate Ltd | Professional & scientific | 2025 |
| Benjamin Peace Paintworks Ltd | Construction | 2023 |
| Bennett & Baxter Limited | Wholesale & retail | 2002 |
| Bentley OT Ltd | Information & communication | 2025 |
| Berchester Consulting Limited | Professional & scientific | 2018 |
| Bereweeke Limited | Financial services | 2017 |
| Bereweeke Property Management Limited | Professional & scientific | 2005 |
| Berin Services Limited | Health & social care | 2019 |
| Berkeley Media Group Limited | Information & communication | 2017 |
| Berkshire Property Ltd | Real estate | 2017 |
| Bermont Project Management Ltd | Other services | 2008 |
| Bernards Gate Residents Management Company Ltd | Households | 2005 |
| Berridge & Co (Builders) Limited | Construction | 2003 |
| Bespoke Aluminium Manufacturing Ltd | Manufacturing | 2021 |
| Bespoke Biking C.I.C. | Other services | 2012 |
| Bespoke Portrait Photography Ltd | Professional & scientific | 2022 |
| Bespoke Smiles of London Limited | Health & social care | 2022 |
| Best Bars Ltd | Hospitality | 2017 |
| Best Creative Solutions Ltd | Professional & scientific | 2023 |
| Best_Medics Limited | Other services | 2006 |
| Better Builds Roofing Ltd | Construction | 2026 |
| Better NOT Perfect Limited | Wholesale & retail | 2025 |
| Better Than Brilliant Ltd | Professional & scientific | 2025 |
| Beximco International Limited | Information & communication | 2024 |
| Beyond Complexity Ltd | Professional & scientific | 2015 |
| Beyond Fashion C.I.C. | Professional & scientific | 2026 |
| Beyond the Barn Ltd | Wholesale & retail | 2017 |
| Bfcl Holdings Ltd | Financial services | 2024 |
| BGR Consulting Limited | Professional & scientific | 2026 |
| BHL Group Limited | Transport & logistics | 2019 |
| Bhse Maidenbower Crawley Management Company Limited | Real estate | 2008 |
| Biaco Energy Limited | Manufacturing | 2023 |
| Biaco Group Limited | Financial services | 2022 |
| Biaco Heating Limited | Manufacturing | 2023 |