| Ashley Grange Nursing Home Limited | Health & social care | 2008 |
| Ashley Head Limited | Professional & scientific | 2003 |
| Asian Group Property Ltd | Real estate | 2026 |
| Asian Oriental Supermarket Ltd | Wholesale & retail | 2023 |
| ASJ Painting & Decorators Ltd | Construction | 2024 |
| ASK Selection Ltd | Administrative & support | 2017 |
| ASK Technology Limited | Manufacturing | 2003 |
| Ask.B.H. Shaw Limited | Construction | 2003 |
| ASP Trans Ltd | Transport & logistics | 2025 |
| Aspencer-Smith & Co Ltd | Professional & scientific | 2019 |
| Aspire BID Support Ltd | Professional & scientific | 2026 |
| Aspire Cultural Home Stay Limited | Administrative & support | 2012 |
| Aspire ID8 Ltd | Professional & scientific | 2021 |
| Aspire Performance Improvement Limited | Professional & scientific | 2013 |
| Assassin Screed Ltd | Construction | 2012 |
| Asset Advantage Group Limited | Financial services | 1992 |
| Asset Advantage Limited | Financial services | 2001 |
| Asset Hire Ltd | Financial services | 2021 |
| Assistify Admin Tranquility Ltd | Administrative & support | 2024 |
| Associated Development Holdings Limited | Construction | 2015 |
| Associated Technology Pipeline Limited | Information & communication | 1998 |
| Assured Ductwork Limited | Construction | 2014 |
| AST Steven Thompson Limited | Wholesale & retail | 2024 |
| Asterion Gate Limited | Financial services | 2026 |
| Asterix Maintenance Ltd | Real estate | 2020 |
| Astir Solutions Limited | Information & communication | 2014 |
| Astra Office Interiors Limited | Construction | 1996 |
| Astronexus Hub Ltd | Wholesale & retail | 2025 |
| Asya Solutions Ltd | Extraterritorial | 2012 |
| AT Steel Design Ltd | Professional & scientific | 2023 |
| Atelier Payne Co. Ltd | Professional & scientific | 2025 |
| Atelier Vidrio Limited | Manufacturing | 2022 |
| Atha WH Limited | Real estate | 2023 |
| Athena Assets Limited | Professional & scientific | 2020 |
| Athena Commercial Cleaning Ltd | Administrative & support | 2014 |
| Athena Communities Limited | Administrative & support | 2023 |
| Athena Homes Limited | Professional & scientific | 2016 |
| Athlane Limited | Professional & scientific | 1994 |
| Atlantic Shores Consulting Limited | Professional & scientific | 2023 |
| Atlanticplus Solution Ltd | Information & communication | 2022 |
| Atlanticserver.Com Ltd | Wholesale & retail | 2026 |
| Atlass Logistic Ltd | Transport & logistics | 2025 |
| Audeo AV Limited | Financial services | 2025 |
| Audeo Limited | Administrative & support | 1999 |
| Audeo Systems Limited | Professional & scientific | 2004 |
| Audi Village(Uk) Limited | Wholesale & retail | 2024 |
| Audient Limited | Manufacturing | 1997 |
| Audio Rent Ltd | Administrative & support | 2025 |
| Aunty Trace Limited | Transport & logistics | 2017 |
| Aura Event Hire Ltd | Arts & recreation | 2023 |
| Aura Studios Creative Ltd | Information & communication | 2024 |
| Auralite Ltd | Manufacturing | 2025 |
| Auream Energy Ltd | Construction | 2013 |
| Auream Investments Ltd | Administrative & support | 2020 |
| Aurelia and Ariana Investments Ltd | Financial services | 2026 |
| Aurora Powder Coatings Ltd | Manufacturing | 2009 |
| Aurora Psychological Therapies Limited | Health & social care | 2020 |
| Aurora World Ltd. | Wholesale & retail | 1997 |
| Aurouz Limited | Wholesale & retail | 2015 |
| Ausben Ltd | Real estate | 2024 |
| Auto Electronix Repair Ltd | Wholesale & retail | 2018 |
| Auto Q Biosciences Limited | Manufacturing | 2003 |
| Auto Repairs Basingstoke Ltd | Wholesale & retail | 2024 |
| Autolocker Ltd | Transport & logistics | 2012 |
| Automobile Association Developments Limited | Administrative & support | 1985 |
| Automobile Association Holdings Limited | Extraterritorial | 1996 |
| Automobile Association Insurance Services Holdings Limited | Extraterritorial | 1989 |
| Automobile Association Insurance Services Limited | Financial services | 1989 |
| Automobile Association Services Limited | Extraterritorial | 1905 |
| Autoquest Car Rentals Limited | Wholesale & retail | 1980 |
| Autoquest Contracts Limited | Wholesale & retail | 1981 |
| Autoquest Limited | Wholesale & retail | 1980 |
| Autotech Roman Road Ltd | Wholesale & retail | 2026 |
| Auxeris Ltd | Administrative & support | 2020 |
| Auxpay Ltd | Information & communication | 2026 |
| Avaajim Property Investment Limited | Real estate | 2025 |
| Avalon Building Services Limited | Construction | 2002 |
| Avary James Limited | Wholesale & retail | 2018 |
| Avenell and Cannon Limited | Construction | 2026 |
| Aviation Oasis Ltd | Other services | 2024 |
| Aviator Claims Solutions Ltd | Professional & scientific | 2024 |
| Aviator Corporate Services Ltd | Other services | 2023 |
| Aviyshair Ltd | Other services | 2020 |
| Avon Aviation Limited | Transport & logistics | 2017 |
| Avtec Fasteners Limited | Manufacturing | 2011 |
| Avyamsh Limited | Information & communication | 2019 |
| Awele Care Ltd | Health & social care | 2021 |
| AWP Creative Design Limited | Professional & scientific | 2021 |
| Axians Networks Limited | Wholesale & retail | 2002 |
| Aximia Limited | Health & social care | 2022 |
| Axiomatise Ltd | Information & communication | 2025 |
| Axylrose Ltd | Wholesale & retail | 2021 |
| Ayficial Data Science & Consulting Ltd | Information & communication | 2018 |
| Aylin Carry Ltd | Transport & logistics | 2018 |
| Ayre Chamberlain Gaunt Ltd. | Professional & scientific | 2005 |
| Ayshtech Ltd | Information & communication | 2025 |
| Ayshtech Property Ltd | Real estate | 2026 |
| AZ DG Consulting Ltd | Information & communication | 2007 |
| Azeee Construction Ltd | Construction | 2016 |
| Azka Automotive Ltd | Wholesale & retail | 2022 |