| Aston Home Care Limited | Administrative & support | 2018 |
| Astro Education Ltd | Administrative & support | 2024 |
| Astrology for Life Ltd | Education | 2024 |
| Astute Fmcg Solutions Ltd | Professional & scientific | 2021 |
| Astwood (Property) Holdings Limited | Financial services | 2026 |
| Astwood (Trade) Holdings Limited | Financial services | 2026 |
| Asyad Limited | Construction | 2016 |
| AT Fast Food Ltd | Hospitality | 2023 |
| AT Management Solutions Ltd | Administrative & support | 2020 |
| ATA Services Limited | Professional & scientific | 2021 |
| Atama Care PVT Ltd | Health & social care | 2024 |
| Ataraxia 2 Limited | Financial services | 2018 |
| Atech Leds Ltd | Construction | 2022 |
| Atelier Bond Limited | Manufacturing | 2026 |
| ATF Funeral Committee Ltd | Other services | 2023 |
| ATG Property Investments Limited | Construction | 2025 |
| Athena Vehicles Limited | Wholesale & retail | 1998 |
| Athenity Limited | Administrative & support | 2025 |
| Athergift Limited | Extraterritorial | 1998 |
| Athlete Fit HQ Ltd | Arts & recreation | 2019 |
| Athleticos Limited | Information & communication | 2011 |
| ATI Speed Transport Ltd | Transport & logistics | 2026 |
| Atipa Healthcare Group Ltd | Health & social care | 2014 |
| Atlanta 1 Insurance Services Limited | Financial services | 1998 |
| Atlantic Motor Zone Ltd | Wholesale & retail | 2024 |
| Atlas Automatics Ltd | Manufacturing | 2006 |
| Atlas Insulation Ltd | Construction | 2023 |
| Atlas Scaffolding Limited | Construction | 1975 |
| Atliwise Ltd | Wholesale & retail | 2024 |
| Atob Homes Ltd | Real estate | 2024 |
| Atoz Chauffeur Services Ltd | Transport & logistics | 2023 |
| Atpbuildingsproperty Ltd | Households | 2025 |
| Atputham MSV Ltd | Wholesale & retail | 2022 |
| ATR Plumbgas Limited | Construction | 2018 |
| Atron RX Online Ltd | Health & social care | 2025 |
| ATS Chauffeur Services Ltd | Transport & logistics | 2023 |
| ATS Construction Limited | Construction | 2020 |
| Atsg Properties Ltd | Real estate | 2023 |
| Atts International Ltd | Other services | 2018 |
| ATW Architecture Ltd | Professional & scientific | 2025 |
| ATW Lettings Ltd | Real estate | 2025 |
| ATZ Trading Limited | Wholesale & retail | 2024 |
| AU Assets Ltd | Administrative & support | 2025 |
| AU Foods Ltd | Hospitality | 2025 |
| AU Holdings Ltd | Financial services | 2025 |
| AU Naturel Holistic Therapies Ltd | Other services | 2025 |
| AU Properties Ltd | Real estate | 2025 |
| Aubrey Design Co. Limited | Professional & scientific | 2003 |
| Auction Hammer Ltd | Real estate | 2023 |
| Audi RS Owners Club Ltd | Wholesale & retail | 2022 |
| Audiology Consultancy Ltd | Health & social care | 2022 |
| Audley Community Action Group. Papg C.I.C. | Other services | 2024 |
| Audley Millennium Green Limited | Extraterritorial | 2013 |
| Audric Ltd | Health & social care | 2022 |
| Aumbow Fulfilment Solutions Limited | Transport & logistics | 2025 |
| Aumbow International Trading Ltd | Transport & logistics | 2013 |
| Aura Deep Clean Limited | Wholesale & retail | 2025 |
| Aura Salon (Cheadle) Limited | Real estate | 2022 |
| Aura Traders Ltd | Wholesale & retail | 2026 |
| Auraluxe Motor Traders Limited | Transport & logistics | 2025 |
| Auremont Developments Ltd | Real estate | 2026 |
| Aurexmotors Limited | Wholesale & retail | 2026 |
| Auris Developments Limited | Construction | 2021 |
| Auris Nominee Limited | Real estate | 2023 |
| Aurorabazaar Ltd | Wholesale & retail | 2023 |
| Auroraca Ltd | Professional & scientific | 2012 |
| Austin & Rowland Property & Developments Limited | Real estate | 2025 |
| Austin Engineering Services Ltd | Construction | 2014 |
| Authentic Translations Ltd | Professional & scientific | 2016 |
| Authentic Vapes Ltd | Wholesale & retail | 2021 |
| Authors & Co Publishing Ltd | Information & communication | 2025 |
| Auto Door Maintenance Specialists Ltd | Manufacturing | 2020 |
| Auto Doors of Stoke Limited | Construction | 2025 |
| Auto Giulia Ricambi Ltd | Wholesale & retail | 2020 |
| Auto Key Assist Stoke Ltd | Other services | 2025 |
| Auto Mechanix (S-On-T) Ltd | Wholesale & retail | 2019 |
| Auto Performance Limited | Extraterritorial | 2003 |
| Auto Repair Centre (Shelton) Limited | Wholesale & retail | 2017 |
| Auto Star Garage Ltd | Wholesale & retail | 2023 |
| Autobody Repairs Limited | Wholesale & retail | 2023 |
| Autocab Private Hire Limited | Transport & logistics | 2010 |
| Autofintech Ltd | Information & communication | 2025 |
| Autoglaze Stoke Limited | Wholesale & retail | 2015 |
| Autoikon Ltd | Wholesale & retail | 2024 |
| Autokeys Locksmith Ltd | Wholesale & retail | 2023 |
| AUTOM8 REC Ltd | Information & communication | 2023 |
| Automation Services Limited | Manufacturing | 1993 |
| Automotive Components Distribution Limited | Wholesale & retail | 2005 |
| Autoneum Great Britain Limited | Manufacturing | 1988 |
| Autonomous Delivery Solutions Limited | Manufacturing | 2020 |
| Autopanel Ltd | Wholesale & retail | 2018 |
| Autoplan Solutions Limited | Manufacturing | 2025 |
| Autorent UK Ltd | Administrative & support | 2012 |
| Autospray Shelton Ltd | Wholesale & retail | 2025 |
| Autospray Systems Limited | Other services | 2016 |
| Autospray Technique Limited | Wholesale & retail | 2013 |
| Autotec Motor Factors Limited | Wholesale & retail | 2003 |
| Autotec Paint & Body Limited | Wholesale & retail | 2011 |
| Autovexis Ltd | Wholesale & retail | 2025 |
| Autumn Willow Aesthetics Limited | Other services | 2025 |