| Audr Intel Ltd | Professional & scientific | 2026 |
| AUG & Elkris Consultants and Engineers Ltd | Administrative & support | 2017 |
| Auksun Consultants Ltd | Professional & scientific | 2004 |
| AUM Consultancy Services Limited | Information & communication | 2019 |
| AUM Software Solutions Limited | Information & communication | 2025 |
| Aura Knight Limited | Wholesale & retail | 2025 |
| Aura Medispa Ltd | Other services | 2025 |
| Aura Solutions Limited | Real estate | 2014 |
| Aurasmi-Properties Limited | Real estate | 2020 |
| Aurasync Limited | Wholesale & retail | 2025 |
| Aurelia Rose Ltd | Wholesale & retail | 2025 |
| Aurelian Properties Ltd | Real estate | 2025 |
| Aurelius Goldsmiths Limited | Wholesale & retail | 2026 |
| Aurias Bidco Ltd | Information & communication | 2024 |
| Aurias Holdco Ltd | Information & communication | 2022 |
| Aurias Midco Ltd | Information & communication | 2024 |
| Aurias Topco Ltd | Information & communication | 2024 |
| Aurora Intelligence Limited | Administrative & support | 2025 |
| Aurora Talent Ltd | Administrative & support | 2025 |
| AUS Mart Ltd | Wholesale & retail | 2025 |
| Auscan Healthfoods Ltd | Wholesale & retail | 2023 |
| Ausnz Pharma Ltd | Wholesale & retail | 2023 |
| Ausrail Ltd | Administrative & support | 2014 |
| Australian Travels Ltd | Administrative & support | 2026 |
| Author in ME Ltd | Information & communication | 2016 |
| Auto Clinic (High Wycombe) Limited | Wholesale & retail | 2013 |
| Auto Improvements Limited | Wholesale & retail | 2009 |
| Auto Medics Limited | Wholesale & retail | 2024 |
| Auto QA Hub Ltd | Information & communication | 2023 |
| Auto Regalia Limited | Wholesale & retail | 2005 |
| Auto Repair Centre (ARC) Limited | Wholesale & retail | 2025 |
| Auto Rust Prevention (ARP) Ltd | Wholesale & retail | 2020 |
| Auto TEC Services Ltd | Wholesale & retail | 2023 |
| Auto Transport Services Ltd | Transport & logistics | 2025 |
| Autocare Direct Ltd | Wholesale & retail | 2026 |
| Autocast Ltd | Information & communication | 2023 |
| Autodocs (H.W) Ltd | Wholesale & retail | 2024 |
| Autohaven Motors Limited | Wholesale & retail | 2019 |
| Autolink Motor Group Ltd | Wholesale & retail | 2020 |
| Automarket 22 Ltd. | Other services | 2015 |
| Automated Business Systems Limited | Information & communication | 1995 |
| Automation QA Ltd | Professional & scientific | 2015 |
| Automedica Ltd | Information & communication | 2023 |
| Automotive Design Technology Ltd | Professional & scientific | 2012 |
| Autonomous U Ltd | Professional & scientific | 2025 |
| Autopartz Distribution Limited | Wholesale & retail | 2015 |
| Autotech House Ltd | Wholesale & retail | 2025 |
| Autoupgrades London Ltd | Wholesale & retail | 2023 |
| Autowerks Services Limited | Wholesale & retail | 2008 |
| Autumn Developments Ltd | Construction | 2022 |
| Autumnwood Limited | Construction | 2019 |
| Auxo Business Services Ltd | Information & communication | 2016 |
| Auzda Ltd | Real estate | 2020 |
| AV Leisure Ltd | Hospitality | 2023 |
| AV2 Motorcycles Ltd | Wholesale & retail | 2024 |
| AVA Hazlemere Limited | Construction | 2025 |
| Avanti Interiors Limited | Construction | 2014 |
| Avellana Consulting Limited | Professional & scientific | 2018 |
| Avenir Roofing Limited | Construction | 2003 |
| Avenue Accountancy Ltd | Professional & scientific | 2026 |
| Avenue Insurance Partners Limited | Financial services | 2016 |
| Avery Dennison U.K. Limited | Manufacturing | 1963 |
| AVI and JAS Limited | Hospitality | 2025 |
| AVI Foods London Ltd | Hospitality | 2025 |
| AVI IT Consulting Ltd | Information & communication | 2019 |
| Avi-I Solutions Limited | Professional & scientific | 2023 |
| Aviantic Ltd | Transport & logistics | 2026 |
| Aviation Consultant Engineering Services Ltd | Information & communication | 2019 |
| Avil Corporation Ltd | Wholesale & retail | 2025 |
| Avinity Limited | Wholesale & retail | 2020 |
| Avonbar Holdings Limited | Financial services | 2021 |
| Avonbar Property Limited | Real estate | 2025 |
| Avondale Contract Services Ltd | Construction | 2000 |
| Avonsome Day Nursery Ltd | Administrative & support | 2018 |
| Avostar Limited | Information & communication | 2015 |
| Avtroid Ltd | Wholesale & retail | 2022 |
| AW Building & Brickwork Ltd | Construction | 2025 |
| AW20 Transport Ltd | Transport & logistics | 2021 |
| AWS Textiles Ltd | Wholesale & retail | 2026 |
| Axefield Ltd | Construction | 2023 |
| Axiom EYE Ltd | Information & communication | 2025 |
| Axioms Consulting Ltd | Other services | 2012 |
| Axitrading Limited | Wholesale & retail | 2019 |
| Axon Therapy Ltd | Health & social care | 2018 |
| AY Construction Ltd | Construction | 2022 |
| Ayah Properties HW Ltd | Real estate | 2026 |
| Ayes Invest Limited | Real estate | 2018 |
| Ayisha Homes Ltd | Real estate | 2019 |
| Aymia Properties Limited | Real estate | 2025 |
| Ayub Holdings and Investments Ltd | Financial services | 2025 |
| Ayub Investments Ltd | Real estate | 2025 |
| Ayzel Recovery Limited | Wholesale & retail | 2025 |
| AZ and Co Solutions Ltd | Administrative & support | 2019 |
| AZ Technical Consultants Limited | Administrative & support | 2001 |
| AZA Homeimprovement Limited | Construction | 2020 |
| Azad Removals Ltd | Transport & logistics | 2025 |
| Azam World Investments Limited | Financial services | 2025 |
| Azaraq Limited | Information & communication | 2021 |
| Azark Ltd | Professional & scientific | 2025 |
| Azdio Limited | Information & communication | 2007 |