| Bluoak Housing and Healthcare Consultancy Limited | Administrative & support | 2018 |
| Blydan Projects Ltd | Construction | 2024 |
| BM Online Ltd | Wholesale & retail | 2024 |
| BM Payments Services Limited | Other services | 2013 |
| Bmac (Holdings) Limited | Other services | 2008 |
| BMB Partners Ltd | Real estate | 2025 |
| BMC Marine Limited | Arts & recreation | 2024 |
| BMC Plastering and Drylining Ltd | Construction | 2024 |
| BMC Plastering Ltd | Construction | 2016 |
| Bmdmihai Ltd | Construction | 2025 |
| BMF Property Limited | Real estate | 1980 |
| BMG Bathrooms and Plumbing Services Limited | Construction | 2014 |
| BMG Plumbing Services Limited | Construction | 2006 |
| Bmlp (Hants) Limited | Hospitality | 2015 |
| BMO Afro Taste Ltd | Wholesale & retail | 2025 |
| Bmpfibre Ltd | Information & communication | 2023 |
| BMS Building Master Specialist Ltd | Construction | 2023 |
| BMS Building Solutions Southern Limited | Construction | 2021 |
| BMS House Conversions Ltd | Construction | 2024 |
| BMS Southern Limited | Professional & scientific | 2008 |
| BMT Productions Ltd | Arts & recreation | 2019 |
| Bmunya Couriers Ltd | Transport & logistics | 2023 |
| BMV Ltd | Extraterritorial | 2025 |
| BMZ Limited | Financial services | 2015 |
| Bn'C Hospitality & Entertainment Management Ltd | Professional & scientific | 2025 |
| BNC Spedition Ltd | Transport & logistics | 2026 |
| BNG26 Ltd | Administrative & support | 2026 |
| Bnkk Estates Ltd | Real estate | 2021 |
| Bnkk Ltd | Construction | 2017 |
| BNS23 Ltd | Administrative & support | 2025 |
| Boakye-A Limited | Administrative & support | 2016 |
| Board Game Extras Limited | Wholesale & retail | 2010 |
| Board in the City CIC | Administrative & support | 2015 |
| Boardriders UK Ltd | Wholesale & retail | 2002 |
| Boat Sales Worldwide Ltd | Wholesale & retail | 2024 |
| Boat Tech Ltd | Manufacturing | 2020 |
| Boat Transport Limited | Transport & logistics | 2002 |
| Boat Yard Services (River Hamble) Ltd | Manufacturing | 2019 |
| Boatbuilding News Ltd | Information & communication | 2022 |
| Boatcare Limited | Other services | 1996 |
| Boatcare Marine Limited | Manufacturing | 2025 |
| Boatfolk Bars Limited | Hospitality | 2020 |
| Boatfolk Cleanco Limited | Professional & scientific | 2015 |
| Boatfolk Limited | Professional & scientific | 2015 |
| Boatfolk Marina Group Limited | Professional & scientific | 2015 |
| Boatfolk Marinas Limited | Arts & recreation | 1992 |
| Boatfolk Midco Limited | Professional & scientific | 2015 |
| Boatpaint Ltd. | Wholesale & retail | 2009 |
| Boatpoint Limited | Wholesale & retail | 2017 |
| Boats Already Ltd | Manufacturing | 2020 |
| Boats to Roam Limited | Wholesale & retail | 2019 |
| BOB and Paula's Limited | Wholesale & retail | 2020 |
| BOB Harland Consultancy Limited | Professional & scientific | 2013 |
| Boba Village Ltd | Wholesale & retail | 2023 |
| Bobby TV Limited | Information & communication | 2022 |
| Bobby-Jo Bottomley Transformational Clinics Ltd | Health & social care | 2022 |
| Bobo Locum Ltd | Health & social care | 2024 |
| Bobs Plumbing Limited | Construction | 2016 |
| Bodyglowstudio Ltd | Other services | 2023 |
| Bodyshopfuy Limited | Wholesale & retail | 2026 |
| Bodyworx Health Clinic Ltd. | Health & social care | 2012 |
| Boga Lettings Ltd | Real estate | 2025 |
| Bogdan Groundworks Ltd | Construction | 2026 |
| Bohemian Belle Ltd | Wholesale & retail | 2019 |
| Boilercare (Southampton) Ltd. | Extraterritorial | 1987 |
| Boilers R US Southampton Limited | Construction | 2012 |
| Boiling Point Plumbing & Heating Limited | Construction | 2011 |
| Boka Distribution Ltd | Wholesale & retail | 2024 |
| Bolberry Court Management Limited | Households | 1995 |
| Bold Boundaries Transport Limited | Transport & logistics | 2024 |
| Bold. Beautiful. Tenacious. CIC | Health & social care | 2025 |
| Boldre Estates Limited | Real estate | 2006 |
| Boleyn SEO Limited | Information & communication | 2017 |
| Bolina Consulting Ltd | Information & communication | 2018 |
| Bolton Auto Group Ltd | Wholesale & retail | 2026 |
| Boltons (Bournemouth) Management Company Limited (the) | Households | 1968 |
| Bolus Brain Ltd | Wholesale & retail | 2026 |
| Boma Creative Limited | Professional & scientific | 2014 |
| Bombacious Ltd | Manufacturing | 2022 |
| Bombaz International Ltd | Transport & logistics | 2023 |
| Bona Fide Healthcare Professionals Limited | Health & social care | 2019 |
| Bonaventure Road Management Company Ltd | Real estate | 2022 |
| Bonbirds Flame Ltd | Hospitality | 2025 |
| Bond Brick Limited | Construction | 1999 |
| Bond Living Ltd | Wholesale & retail | 2023 |
| Bond Property Holdings Limited | Construction | 2018 |
| Bond Recruit Limited | Administrative & support | 2018 |
| Bond Street Consultants Limited | Other services | 2010 |
| Bond Villain Media Ltd | Professional & scientific | 2019 |
| Bondeck Limited | Construction | 2004 |
| Bonded Holdings Limited | Information & communication | 2023 |
| Bones Restaurant Group Limited | Hospitality | 2022 |
| Bones Restaurant Group Midco Limited | Financial services | 2022 |
| Bones Restaurant Group Topco Limited | Financial services | 2022 |
| Bonjor Ltd | Information & communication | 2019 |
| Bonne Bouche Ltd | Hospitality | 2014 |
| Bonnici Estates Limited | Real estate | 2023 |
| Bonnici Global Solutions Limited | Professional & scientific | 2020 |
| Bonnies of Bitterne Ltd | Hospitality | 2025 |
| Bonsai Socials Ltd | Professional & scientific | 2024 |