| Anglia Scholars Educational Consultancy Limited | Education | 2000 |
| Anim Tree Limited | Information & communication | 2025 |
| Anima Veicoli Ltd | Wholesale & retail | 2014 |
| Animal Life Limited | Other services | 2022 |
| Animation Adrenaline Ltd | Information & communication | 2024 |
| Anmore Properties Limited | Real estate | 2018 |
| ANN Apartments Ltd | Real estate | 2020 |
| Annata Limited | Information & communication | 2011 |
| Annieangels Solutions Ltd | Health & social care | 2019 |
| Anonymous Climbing Club CIC | Arts & recreation | 2025 |
| ANOV8 Limited | Professional & scientific | 2024 |
| Anschuetz UK Ltd | Administrative & support | 2022 |
| Anson + Jackson Limited | Construction | 1999 |
| Anson Electrical Services Ltd | Construction | 2026 |
| ANT Logistics Ltd | Transport & logistics | 2018 |
| Antel Ltd | Wholesale & retail | 2006 |
| Anthroplay Theatre Ltd. | Administrative & support | 2020 |
| Anticus Ltd | Real estate | 2013 |
| Antogher Solutions Ltd | Construction | 2024 |
| Anumor Ltd | Wholesale & retail | 2025 |
| Anwulf Stead Limited | Real estate | 2024 |
| AOF Group Ltd | Information & communication | 2023 |
| AOX Property Solutions Ltd | Real estate | 2024 |
| AP Dove Limited | Extraterritorial | 2024 |
| AP2 Property Limited | Real estate | 2024 |
| Apace Consulting Limited | Information & communication | 2013 |
| APC Group Holdings Ltd | Financial services | 2022 |
| Apeiron Marketing Solutions Limited | Professional & scientific | 2023 |
| Apex Capital Estates Ltd | Real estate | 2021 |
| Apex Cars and Commercials Ltd | Wholesale & retail | 2025 |
| Apex Dyslexia Assessment Limited | Education | 2025 |
| Apex Home Enhancements Ltd | Construction | 2021 |
| Apex Mechanical Projects Ltd | Construction | 2019 |
| Apex Paving Limited | Construction | 2021 |
| Apex Southern Limited | Manufacturing | 2024 |
| Apis (Peckham) Limited | Financial services | 2021 |
| APJ European Supplies Limited | Wholesale & retail | 1994 |
| Apollo Digital Consultants Ltd | Information & communication | 2017 |
| Apostle Consulting Limited | Professional & scientific | 2019 |
| App Decorating Ltd | Construction | 2019 |
| Applecore Property Services Ltd | Real estate | 2022 |
| Appleford Court Management Limited | Households | 2012 |
| Appley Leisure Group Limited | Financial services | 2015 |
| Appley Park Leisure Limited | Hospitality | 1999 |
| Appliance Care (Portsmouth) Ltd | Manufacturing | 2017 |
| Applied Brilliance Limited | Other services | 2010 |
| Approachways Limited | Construction | 2010 |
| Approve Finance Ltd | Financial services | 2026 |
| Approve Group Limited | Financial services | 2026 |
| Approve Services Limited | Administrative & support | 2018 |
| Approved Accounting Ltd | Professional & scientific | 1999 |
| Approved Cleaning Ltd | Administrative & support | 2026 |
| Approved Recovery Limited | Professional & scientific | 2019 |
| Approved Security Ltd | Administrative & support | 2026 |
| Apricotsunset Limited | Administrative & support | 2006 |
| APS Verifications Limited | Construction | 2008 |
| Aqua Car Wash Portsmouth Ltd | Wholesale & retail | 2022 |
| Aqua Garage Services Limited | Wholesale & retail | 2013 |
| Aqua GAS Heating and Plumbing ( Southern ) Ltd | Construction | 2021 |
| Aqua-Marine Services Ltd | Manufacturing | 2017 |
| Aquarius Court Limited | Administrative & support | 2013 |
| Aqueous Pools Limited | Construction | 2016 |
| Aquila Qualitas Ltd | Professional & scientific | 2019 |
| AR 100 Limited | Professional & scientific | 2026 |
| AR Management Services Ltd | Professional & scientific | 2025 |
| AR Metal Recycling Ltd | Water & waste | 2017 |
| Araj Legalops Consulting Ltd | Other services | 2023 |
| Aramao Developments Ltd | Construction | 2023 |
| Aramao Ltd | Construction | 2021 |
| Arashmed Ltd | Wholesale & retail | 2022 |
| ARB Development Projects Limited | Professional & scientific | 1984 |
| ARB Mechanical Engineering Limited | Construction | 2007 |
| ARB Rotary Engineering Limited | Professional & scientific | 2022 |
| Arbrook Tree Care Limited | Administrative & support | 2005 |
| ARC (Portsmouth)Property Company Limited | Real estate | 2025 |
| ARC Expert Ltd | Wholesale & retail | 2021 |
| ARC Property Maintenance & Home Improvements Ltd | Construction | 2013 |
| ARC Reclamation Limited | Wholesale & retail | 2004 |
| ARC West Street Limited | Manufacturing | 2016 |
| Arca & AST Limited | Health & social care | 2022 |
| Arca Bidco Limited | Financial services | 2014 |
| Arca Holdco Limited | Financial services | 2014 |
| Arca Midco Limited | Financial services | 2014 |
| Arca Shipping Limited | Financial services | 2005 |
| Arca Topco Limited | Financial services | 2014 |
| Arcade Belts Limited | Wholesale & retail | 2016 |
| Arcadia Heating & Plumbing Services Limited | Construction | 2001 |
| Archi+Build Ltd | Construction | 2020 |
| Archimedes Metals Limited | Water & waste | 2003 |
| Archiplus Ltd | Professional & scientific | 2010 |
| Architectural Systems Technology Limited | Manufacturing | 1998 |
| Archon Construction Ltd | Construction | 2021 |
| Arcus Mendes Ltd | Wholesale & retail | 2012 |
| Ardent Building & Structual Repairs Limited | Construction | 2008 |
| Ardent Performance Ltd | Construction | 2021 |
| Ardour Associates Ltd | Administrative & support | 2022 |
| Ardour Properties Ltd | Real estate | 2025 |
| Arena Developments (Ryde) Ltd | Hospitality | 2026 |
| Ares Group Services Ltd. | Professional & scientific | 2015 |
| Arete Marketing Consultancy Limited | Professional & scientific | 2016 |