| Balscote Trustees (NO1) Ltd | Financial services | 2022 |
| Balscote Trustees (NO2) Ltd | Financial services | 2022 |
| Baltic Tanker Limited | Transport & logistics | 2022 |
| Baluyo Limited | Health & social care | 2015 |
| Balvin Properties Ltd | Real estate | 2025 |
| BAM Mechanical Limited | Construction | 2024 |
| Bamboo 1 Lending Limited | Financial services | 2020 |
| Bamboo 2 Lending Limited | Financial services | 2020 |
| Bamboo Limited | Financial services | 2005 |
| Bamboo Solutions Building Groundworks Ltd | Construction | 2022 |
| Bamboo Topco Limited | Financial services | 2016 |
| Bamboo Vietnam Ltd | Health & social care | 2023 |
| Bamuir Investments Limited | Real estate | 1964 |
| Banair Limited | Professional & scientific | 1990 |
| Banana Monkey Ltd | Information & communication | 2003 |
| Banana Wharf Limited | Hospitality | 2005 |
| Bandaid First AID Training Limited | Education | 2018 |
| Bandshield Limited | Professional & scientific | 2009 |
| Baneshi Travel Ltd | Transport & logistics | 2026 |
| Bangel Assets Management Ukeig | | 2016 |
| BANGEL82 Limited | Administrative & support | 2015 |
| Banister Park (Southampton) Management Company Limited | Households | 1989 |
| Banister Park Bowling Club Limited | Arts & recreation | 2023 |
| Banmitcom Limited | Transport & logistics | 2016 |
| Banner Press Limited | Manufacturing | 2023 |
| Bannister Court Management (Southampton) Company Limited | Households | 2001 |
| Bano Washroom Ltd | Construction | 2021 |
| BANTABA4CHANGE CIC | Administrative & support | 2018 |
| Banto Trans Ltd | Transport & logistics | 2017 |
| Bany Property Limited | Real estate | 2026 |
| BAO Brothers Ltd | Hospitality | 2024 |
| Bar SO16 Ltd | Hospitality | 2019 |
| Bara Transport Limited | Transport & logistics | 2015 |
| Baragu Ltd | Wholesale & retail | 2022 |
| Baraka Health Ltd | Health & social care | 2020 |
| Barakah Hythe Limited | Hospitality | 2017 |
| Barakah Lettings Ltd | Real estate | 2026 |
| Baram JTC Limited | Financial services | 2017 |
| Baram Limited | Construction | 1994 |
| Baranowski Ltd | Transport & logistics | 2018 |
| Barav Traders Ltd | Construction | 2026 |
| Barber Audiology Limited | Health & social care | 2016 |
| Barber-Wylie Property Limited | Real estate | 2022 |
| Barberlabco Ltd | Other services | 2023 |
| Barbican Consulting Limited | Professional & scientific | 2016 |
| Barbier Cleaning Services Limited | Administrative & support | 2017 |
| Barbu Andrei Ltd | Transport & logistics | 2019 |
| Barbu MA Limited | Transport & logistics | 2020 |
| Barclay Hamp Ltd | Administrative & support | 2022 |
| Bardavio & Diaz Limited | Real estate | 2021 |
| Bardavio Ltd | Health & social care | 2017 |
| Bardhvac UK Ltd | Energy | 2021 |
| Barely Grown Productions Ltd | Information & communication | 2023 |
| Barga Eastleigh Ltd | Hospitality | 2026 |
| Bargate Mews Management Limited | Hospitality | 2008 |
| Bargate Professional Group LLP | | 2017 |
| Bargate Projects Ltd | Construction | 2026 |
| Barjer International Group Investments Limited | Financial services | 2026 |
| Bark & Steel Ltd | Manufacturing | 2019 |
| Bark and Brave Ltd | Wholesale & retail | 2023 |
| Barkat Ltd | Hospitality | 2024 |
| Barker & Co. Ltd | Administrative & support | 2001 |
| Barker & Mallory Press Ltd | Information & communication | 2024 |
| Barker Medicals Supply Limited | Administrative & support | 2014 |
| Barkley Management Ltd | Professional & scientific | 2020 |
| Barna and Company Limited | Administrative & support | 1995 |
| Barna Care Limited | Administrative & support | 2020 |
| Barnard Consultants Ltd | Financial services | 2004 |
| Barnes of Lincoln Limited | Transport & logistics | 2001 |
| Barnes Smart Solutions Limited | Information & communication | 2017 |
| Barnes Window Cleaning (Commercial) Ltd | Administrative & support | 2025 |
| Barnes Window Cleaning Ltd | Administrative & support | 2023 |
| Barnett Ltd | Extraterritorial | 2015 |
| Barnett Plumbing and Heating Limited | Construction | 2004 |
| Barney Parks Limited | Real estate | 2022 |
| Barnikels Limited | Transport & logistics | 2019 |
| Baron's Mead (Southampton) Management Limited | Households | 1997 |
| Baronia Restaurants Limited | Hospitality | 2011 |
| Barovar Ltd | Information & communication | 2026 |
| Barraquito Ltd | Hospitality | 2025 |
| Barrelsfurniture Ltd | Manufacturing | 2024 |
| Barren Blasting & Painting Ltd | Construction | 2017 |
| Barrett Jordan Limited | Administrative & support | 2020 |
| Barrie Financial Services Limited | Financial services | 2002 |
| Barrington Rose Limited | Households | 2011 |
| Barron Archive Ltd. | Wholesale & retail | 2025 |
| Barron Developments Wessex Limited | Real estate | 2002 |
| Barry Holdsworth Limited | Professional & scientific | 2002 |
| Barry Motor Trade Ltd | Wholesale & retail | 2023 |
| Barry Westerman Ltd | Construction | 2021 |
| Bartholomew Guitars Ltd | Manufacturing | 2021 |
| Bartlett Electrical Ltd | Construction | 2020 |
| Bartlett Publications & Products Ltd | Extraterritorial | 2006 |
| Bartletts of Winchester Limited | Wholesale & retail | 2023 |
| Bartley Garage Limited | Wholesale & retail | 2013 |
| Bartley West Limited | Administrative & support | 2013 |
| Barton Trading Limited | Wholesale & retail | 2009 |
| Barton Wykes Ltd. | Real estate | 2011 |
| Barwell House Properties Limited | Real estate | 1961 |
| Barzey Advisory Limited | Extraterritorial | 2013 |