| Burgoyne Estates Limited | Wholesale & retail | 2022 |
| Burgshake Restaurant Southampton Ltd | Hospitality | 2022 |
| Burhan Ocean Cafe Ltd | Hospitality | 2025 |
| Burhanbey Ltd | Hospitality | 2025 |
| Burke Drive Ltd | Real estate | 2025 |
| Burlove 21 Limited | Construction | 2024 |
| Burlove Trading Ltd | Wholesale & retail | 2017 |
| Burnaby SPV Limited | Real estate | 2022 |
| Burnage Associates Limited | Information & communication | 2004 |
| Burnage House (Management) Co. Limited | Real estate | 1972 |
| Burnett Heating Solutions Limited | Construction | 2021 |
| Burnetts Lane (Southampton) NO 2 Limited | Households | 2003 |
| Burnham Concepts Ltd | Construction | 2020 |
| Burns Place Residents Management Limited | Households | 1986 |
| Burnt Ends Ltd | Arts & recreation | 2024 |
| Burntwood (Cheam) Limited | | 1933 |
| Burrbeck Limited | Real estate | 2019 |
| Burridge Dental Practice Ltd | Health & social care | 2010 |
| Burrwood Contracts Ltd | Construction | 2005 |
| Bursledon & District Community Association | Other services | 2012 |
| Bursledon Brickworks Museum Trust | Arts & recreation | 2015 |
| Bursledon Brickworks Trading Limited | Arts & recreation | 2018 |
| Bursledon Heights Management Co.Limited | Households | 1966 |
| Bursledon Motors Limited | Wholesale & retail | 2002 |
| Bursledon Outboards Sales & Service Ltd | Manufacturing | 2010 |
| Burwood Homes Ltd | Construction | 2025 |
| Bushey Mill Lane Management Company Limited | Households | 1997 |
| Busikids Limited | Other services | 1997 |
| Business Accounting and Tax Ltd | Professional & scientific | 2012 |
| Business Components Limited | Information & communication | 1998 |
| Business Intelligence Management Ltd | Professional & scientific | 2015 |
| Business Networking Dorset Ltd. | Other services | 2014 |
| Business Orientated Software Solutions Limited | Information & communication | 2006 |
| Business Process Management Solutions Limited | Professional & scientific | 2013 |
| Business Relocations Limited | Extraterritorial | 2024 |
| Business South Limited | Administrative & support | 2006 |
| Busy BEE Mortgage and Protection Solutions Limited | Financial services | 2021 |
| Busy BEE Products Limited | Wholesale & retail | 2016 |
| Busy Berts Limited | Hospitality | 2023 |
| Butaem Ltd | Information & communication | 2025 |
| Butchers Block BBQ Ltd | Hospitality | 2022 |
| Butcher’S Hook Limited | Hospitality | 2017 |
| Butler & Co (Bishops Waltham) Limited | Professional & scientific | 2005 |
| Butler Engineering Contracting Services Limited | Professional & scientific | 2018 |
| Butler House Limited | Professional & scientific | 2019 |
| Butler Renewables Ltd | Construction | 2024 |
| Butlers Cleaning Service Limited | Other services | 2014 |
| Buttercup PUB Limited | Hospitality | 2023 |
| Buttercups Nursery School Ltd | Education | 2006 |
| Buyamotorhome Ltd. | Extraterritorial | 2009 |
| Buys Cleaning Ltd | Administrative & support | 2025 |
| Buys Homes Ltd | Real estate | 2024 |
| Buywithnoman Ltd | Wholesale & retail | 2025 |
| Buzatu Ltd | Transport & logistics | 2025 |
| BV Southampton Tyres Ltd | Wholesale & retail | 2022 |
| BVM Care Limited | Health & social care | 2021 |
| BW Garage Ltd | Wholesale & retail | 2026 |
| BW Residential Limited | Real estate | 2011 |
| BWG Consult Limited | Professional & scientific | 2013 |
| BWG Healthcare Limited | Administrative & support | 2022 |
| Bwhiting Limited | Information & communication | 2025 |
| BWR Corporate Services Limited | Administrative & support | 2022 |
| BXA Renovation Services Ltd | Construction | 2024 |
| BY Guidance Limited | Financial services | 2025 |
| BY Property Investments Ltd | Real estate | 2016 |
| BY the Way Property Maintenance Ltd. | Real estate | 2014 |
| Byba Transport Limited | Transport & logistics | 2018 |
| Bylko Ltd | Construction | 2022 |
| Byrne & Watts Builders Ltd | Construction | 2023 |
| Byron Electrical Installations Ltd | Arts & recreation | 2002 |
| Byworth Properties Limited | Real estate | 1999 |
| Byzops Limited | Information & communication | 2025 |
| C & C Holdings Limited | Professional & scientific | 1996 |
| C & C Reconditioning Limited | Financial services | 2012 |
| C & C Signs Limited | Manufacturing | 2013 |
| C & E Carpentry Ltd | Construction | 2026 |
| C & J Auto's Ltd | Wholesale & retail | 2011 |
| C & K Plumbing and Heating Ltd | Construction | 2024 |
| C & K Scaffolding Limited | Construction | 2010 |
| C & P Property Improvements & Maintenance Ltd | Construction | 2016 |
| C & T Lettings Ltd | Real estate | 2025 |
| C B Jointing Limited | Construction | 2011 |
| C Bespoke Cleaning Services Ltd. | Administrative & support | 2025 |
| C Bhakar Catering Limited | Hospitality | 2024 |
| C Brooker Consulting Ltd | Professional & scientific | 2021 |
| C D Reilly Construction Ltd | Construction | 2025 |
| C Dent-Al Therapy Limited | Health & social care | 2026 |
| C F Freelance Limited | Agriculture & fishing | 2025 |
| C G Brooks Limited | Professional & scientific | 2014 |
| C G Godfrey Limited | Construction | 1988 |
| C Gkikas Limited | Health & social care | 2014 |
| C Howe Electrical Ltd | Manufacturing | 2020 |
| C J Morgan Limited | Health & social care | 2012 |
| C J Property Sales Limited | Wholesale & retail | 2022 |
| C J R Glass & Glazing Limited | Construction | 2012 |
| C K Firrell Accountancy Services Ltd | Professional & scientific | 2014 |
| C K Plumbing and Heating (Southern) Limited | Construction | 2016 |
| C M Corney Holdings Limited | Financial services | 2012 |
| C M Corney Limited | Transport & logistics | 2016 |
| C M Cowley Building Limited | Construction | 2004 |