| Athena Home Projects Ltd | Construction | 2023 |
| Athena North Walls Limited | Households | 2019 |
| Athena P3M Ltd | Professional & scientific | 2025 |
| Athkar Medical Ltd | Health & social care | 2015 |
| Athlon Management Limited | Administrative & support | 2022 |
| Atlantic Ribs Ltd | Wholesale & retail | 2021 |
| Atmosphere Hot Air Balloons Limited | Extraterritorial | 2019 |
| Atpm Limited | Real estate | 2013 |
| Atrium Court Holdco LLP | | 2024 |
| Audlla Accounting Ltd | Professional & scientific | 2025 |
| Audrey's Tea Rooms Ltd | Hospitality | 2023 |
| Aura Jewellery Ltd | Wholesale & retail | 2012 |
| Aurelia Advisory Limited | Professional & scientific | 2014 |
| Aureus Agency Ltd | Extraterritorial | 2022 |
| Auricom Limited | Information & communication | 2022 |
| Austen House Management Limited | Real estate | 2013 |
| Austin Holdings (Southern) Limited | Professional & scientific | 2022 |
| Auto 100 Select Ltd | Wholesale & retail | 2024 |
| Autobarn Supercar Sales Ltd | Wholesale & retail | 2023 |
| Autom Ltd | Information & communication | 2025 |
| Automotive Projects Limited | Professional & scientific | 1998 |
| Automwrite Ltd | Information & communication | 2023 |
| Avanti Advice Limited | Professional & scientific | 2017 |
| Aventa Properties Limited | Hospitality | 2003 |
| Avenue One Property Development Ltd | Construction | 2026 |
| Average Romp Ltd | Information & communication | 2021 |
| Avexia Limited | Professional & scientific | 2008 |
| Aviation Resource Development (UK) Limited | Information & communication | 1999 |
| Avilstron Ltd | Information & communication | 2020 |
| Avlaw Limited | Professional & scientific | 2016 |
| Avocado Marketing Limited | Information & communication | 2017 |
| Avondale House (Freehold) Limited | Households | 2018 |
| AW Media Group Ltd | Professional & scientific | 2025 |
| Awbridge Arborists Limited | Administrative & support | 2015 |
| Awesome Ninja Limited | Administrative & support | 2019 |
| Awoc Accountants Limited | Transport & logistics | 2016 |
| Awoc HUN Solution Limited | Administrative & support | 2018 |
| Axminster Carpets (Factory Outlet) Limited | Wholesale & retail | 2020 |
| Aycee Apothec Ltd | Manufacturing | 2024 |
| Aymer Estates LLP | | 2025 |
| Ayrewaves Limited | Information & communication | 2003 |
| AZ Huron Ltd | Real estate | 2022 |
| AZ Property Ltd | Real estate | 2016 |
| Aznewton Ltd | Hospitality | 2026 |
| Azul Group Ltd | Real estate | 2023 |
| Azure Capital Partners Ltd | Administrative & support | 2011 |
| B D M Squared Limited | Professional & scientific | 2017 |
| B D Resources Limited | Professional & scientific | 2003 |
| B G Legal Services Limited | Professional & scientific | 2006 |
| B Marchant Ltd | Professional & scientific | 2025 |
| B&I Ltd | Education | 2019 |
| B&K Quality Ltd | Construction | 2019 |
| B-Line Surveys Ltd | Professional & scientific | 2024 |
| B.E. Chaplin (Gunmakers) Limited | Manufacturing | 2021 |
| B.O.P Becoming OUR Potential C.I.C. | Professional & scientific | 2025 |
| B33 Group Limited | Financial services | 2024 |
| Baby Giant Design Company Limited | Information & communication | 2024 |
| Baby Squids Ltd | Arts & recreation | 2014 |
| Back to Africa Host Ltd | Extraterritorial | 2019 |
| Back to the LAB Limited | Wholesale & retail | 2010 |
| Badgers Copse Management Company Limited | Households | 2003 |
| Bagdis Incorporated Limited | Professional & scientific | 2012 |
| Bahm Architects Ltd | Professional & scientific | 2026 |
| Bailey Enterprises Land Profits Limited | Real estate | 2026 |
| Bakeit Limited | Hospitality | 2025 |
| Baker Creative Design Consultants Ltd | Professional & scientific | 2014 |
| Balanced Accounts and Payroll Services Ltd | Professional & scientific | 2016 |
| Balanced Nature Ltd | Manufacturing | 2016 |
| Balcomb Developments Ltd | Construction | 2024 |
| Balewink Ltd | Wholesale & retail | 2018 |
| Ballater Road Limited | Real estate | 2018 |
| Balloon Trust | Administrative & support | 2007 |
| Baltic Mills Limited | Agriculture & fishing | 1994 |
| Baltic Textile Limited | Wholesale & retail | 2013 |
| Bamaluz Ltd | Construction | 2024 |
| Bambu Executive Search Limited | Administrative & support | 2024 |
| Banchard Limited | Professional & scientific | 2012 |
| Bandito Limited | Information & communication | 2009 |
| Bandmaster Solutions Limited | Agriculture & fishing | 2011 |
| Bangkok Bistro Winchester Limited | Hospitality | 2021 |
| Banister Court (Southampton) Management Company Limited | Households | 2016 |
| Barbara Brown Consultancy Ltd | Information & communication | 2018 |
| Barbilla Solutions Limited | Information & communication | 2025 |
| Barboxes Ltd | Manufacturing | 2022 |
| Bardkins Ltd | Construction | 2025 |
| Barker & SON (UK) Ltd | Professional & scientific | 2020 |
| Barleymow Investments Limited | Financial services | 2025 |
| Barnett Rowell Property Limited | Real estate | 2026 |
| Barre Physique Limited | Arts & recreation | 2018 |
| Bartlett Land Acquisitions Limited | Construction | 2020 |
| Bartley Holdings Limited | Real estate | 2007 |
| Bartley Investments Ltd | Real estate | 2023 |
| Bartley Management Limited | Real estate | 2006 |
| Barton Abbott Limited | Arts & recreation | 2024 |
| Barton Court (Winchester) Management Company Limited | Real estate | 2006 |
| Barton END Holdings | Construction | 2018 |
| Barton END Residents Company Limited | Households | 1978 |
| Barwillow Limited | Real estate | 2022 |
| Baseline Design Limited | Information & communication | 2004 |
| Baseline Training Limited | Professional & scientific | 1998 |