| Abode Financing Ltd | Financial services | 2019 |
| Aboh Homes Ltd | Real estate | 2025 |
| Abolarin Holdings Limited | Other services | 2025 |
| Aboushousha Ltd | Professional & scientific | 2023 |
| About Fitness Ltd | Other services | 2014 |
| Above Bar Church | Other services | 2009 |
| Above Bar Cyber Limited | Information & communication | 2018 |
| Above Board (Solent) Limited | Manufacturing | 2014 |
| ABP Priority Delivery Ltd | Transport & logistics | 2019 |
| Abrams Way Residents Limited | Households | 2015 |
| ABS Auto Repairs Limited | Wholesale & retail | 2018 |
| ABS Financial Planning Limited | Financial services | 1991 |
| Absariq Ltd | Information & communication | 2025 |
| Absea Ventures Limited | Transport & logistics | 2005 |
| Abshot Club Apartments Limited | Other services | 2019 |
| Abshot Estates Limited | Real estate | 2019 |
| Abshot Manor Apartments Limited | Households | 2010 |
| Abshot Manor Cottages Limited | Real estate | 2015 |
| Abshot Members Club Limited | Arts & recreation | 2009 |
| Absolar Solutions Ltd | Professional & scientific | 2019 |
| Absolute Engineering Solutions Limited | Manufacturing | 2014 |
| Absolute Reptile Limited | Wholesale & retail | 2025 |
| Absolutely Wild Limited | Wholesale & retail | 2010 |
| Abstract Publications Limited | Information & communication | 2025 |
| Abstream Limited | Health & social care | 2022 |
| Abstyres Ltd | Wholesale & retail | 2026 |
| Abtech A.V.S.S. Limited | Wholesale & retail | 2003 |
| ABU NUH Endoscopy Ltd | Health & social care | 2022 |
| Abudel Limited | Construction | 2025 |
| Abuye Limited | Wholesale & retail | 2026 |
| Abyasa Holdings Limited | Financial services | 2025 |
| Abyasa Limited | Information & communication | 2007 |
| Abyssinia Ltd | Professional & scientific | 2012 |
| AC Blackfield Valeting and Car Wash Ltd | Wholesale & retail | 2019 |
| AC Capital Consulting Limited | Real estate | 2017 |
| AC Castle Street Ltd | Real estate | 2018 |
| AC Consultancy (Southern) Ltd | Construction | 2024 |
| AC Developments (Southern) Limited | Real estate | 2023 |
| AC Parl Street 2 Ltd | Construction | 2016 |
| AC Rigging and Lifting Ltd | Manufacturing | 2024 |
| AC Semh Education Ltd | Education | 2023 |
| ACA Design Ltd | Professional & scientific | 2016 |
| Academic Future Consultants Ltd | Education | 2025 |
| Acasa Holdings Limited | Real estate | 2026 |
| ACC & Forest Services Limited | Water & waste | 2011 |
| Accelerated Accounts Limited | Real estate | 2024 |
| Accelercomm Ltd | Information & communication | 2016 |
| Accelleo Ltd | Information & communication | 2023 |
| Access Instrumentation Limited | Wholesale & retail | 1989 |
| Access Intruder Systems Limited | Administrative & support | 2004 |
| Access Talent Group Limited | Administrative & support | 2015 |
| Access to Export Limited | Professional & scientific | 2006 |
| ACCESS2 Human Resources Ltd | Administrative & support | 2010 |
| ACCESS2LEARN Holdings Limited | Financial services | 2025 |
| ACCESS2LEARN Ltd | Health & social care | 2015 |
| Accessadvisr Limited | Information & communication | 2012 |
| Accesscentral Limited | Information & communication | 2008 |
| Accfit Ltd | Professional & scientific | 2021 |
| Accident Management Services Limited | Professional & scientific | 2001 |
| Accio Research Limited | Information & communication | 2022 |
| Acclaim Group Holdings Ltd | Transport & logistics | 2014 |
| Acclaim Holdings Limited | Professional & scientific | 2011 |
| Acclaim Logistics Limited | Transport & logistics | 2011 |
| Acclaim Parcel Express (Southampton) Limited | Transport & logistics | 1993 |
| Accolade Project Ltd | Water & waste | 2019 |
| Accommo Link Limited | Real estate | 2015 |
| Accomplice Digital Communications Ltd | Professional & scientific | 2021 |
| Accompt Limited | Professional & scientific | 2023 |
| Accord Medicare Limited | Health & social care | 2015 |
| Account on US Ltd | Professional & scientific | 2018 |
| Accountability (Hants) Limited | Professional & scientific | 2002 |
| Accountableuk Limited | Professional & scientific | 2018 |
| Accountably Aesthetics Limited | Professional & scientific | 2020 |
| Accountably Holdings Ltd | Financial services | 2024 |
| Accountably Limited | Professional & scientific | 2003 |
| Accountancy Connect Ltd | Administrative & support | 2023 |
| Accountancy Innovations Limited | Professional & scientific | 2016 |
| Accountancy Recruitment Limited | Extraterritorial | 1996 |
| Accountants at Work Limited | Professional & scientific | 2007 |
| Accounteract Ltd | Professional & scientific | 2008 |
| Accounting HUT (Southampton) Limited | Professional & scientific | 2026 |
| Accounting Solutions (Southampton) Limited | Professional & scientific | 2003 |
| Accountly Ltd | Professional & scientific | 2024 |
| Accounts & Trade Management Limited | Professional & scientific | 2008 |
| Accura Electrical Ltd | Construction | 2025 |
| Accura Fire Risk Ltd | Professional & scientific | 2026 |
| Accuracy International Limited | Manufacturing | 2005 |
| Accurate Build Limited | Construction | 2024 |
| Accurate Care Limited | Public administration | 2023 |
| Accurate Controls Limited | Manufacturing | 1989 |
| Ace Automotive Southern Limited | Wholesale & retail | 2017 |
| Ace Barber Southampton Ltd | Other services | 2022 |
| Ace BIN Cleaning Ltd | Administrative & support | 2024 |
| Ace Cleaning Domestic Limited | Other services | 2008 |
| Ace Electrical Engineers Limited | Construction | 2003 |
| Ace Golf Tours Ltd | Administrative & support | 2019 |
| Ace Hair Stylist Ltd | Other services | 2025 |
| Ace KNG Media Ltd | Professional & scientific | 2018 |
| Ace Marine Services & Solutions Ltd | Manufacturing | 2010 |
| Ace Mini Market Ltd | Wholesale & retail | 2026 |