| Ausurus Group Ltd | Professional & scientific | 2014 |
| Autane Limited | Information & communication | 2020 |
| Autism Care (Bedford) Limited | Health & social care | 2013 |
| Autism Care (North West) Limited | Health & social care | 2001 |
| Autism Care (Properties) Limited | Real estate | 1993 |
| Autism Care (UK) Limited | Health & social care | 2000 |
| Autism Care Properties (2) Limited | Real estate | 2008 |
| Autism Care UK (2) Limited | Health & social care | 2010 |
| Autism Care UK (3) Limited | Health & social care | 2011 |
| Autism Care UK (4) Limited | Health & social care | 2011 |
| Auto Seven 7 Ltd | Wholesale & retail | 2017 |
| Auto Union Finance Limited | Financial services | 2003 |
| AUTO56 Limited | Wholesale & retail | 2022 |
| Autocare North West Limited | Wholesale & retail | 2019 |
| Autodeals PVT Ltd | Wholesale & retail | 2019 |
| Autofinity Assist Limited | Financial services | 2011 |
| Autofinity Limited | Information & communication | 2012 |
| Autofinity Parts Limited | Wholesale & retail | 2012 |
| Automated Control Solutions Limited | Information & communication | 1998 |
| Automated Prepress Solutions Ltd | Professional & scientific | 2021 |
| Automation & Optimisation Ltd | Professional & scientific | 2019 |
| Automation Solutions and Services Ltd | Manufacturing | 2011 |
| Automove Solutions Limited | Transport & logistics | 2024 |
| Autoquest Knutsford Limited | Wholesale & retail | 2022 |
| Autoquest Services Limited | Wholesale & retail | 2025 |
| Autospace Design Limited | Transport & logistics | 1997 |
| AV Training and Services Ltd | Professional & scientific | 2011 |
| AV8 Consultants Ltd | Administrative & support | 2024 |
| AVA Manager Ltd | Information & communication | 2015 |
| Avacyn Solutions Limited | Professional & scientific | 2026 |
| Available Grants Limited | Administrative & support | 2020 |
| Availnet Ltd | Information & communication | 2012 |
| Avamber Projects Limited | Construction | 2024 |
| Avani Computing Ltd | Information & communication | 2023 |
| Avantage (Cheshire) Holdings Limited | Professional & scientific | 2007 |
| Avantage (Cheshire) Limited | Hospitality | 2007 |
| Avdel Holding Limited | Professional & scientific | 1936 |
| Avdel UK Limited | Manufacturing | 1936 |
| Aventus Door Systems Ltd | Construction | 2025 |
| Avenue 54 Ltd | Administrative & support | 2021 |
| Avenue Agents Ltd | Administrative & support | 2022 |
| Avery Drainage Solutions Ltd | Construction | 2021 |
| Avex Aero Limited | Administrative & support | 2023 |
| Avica Consulting Limited | Administrative & support | 2012 |
| Avid Advantage Limited | Professional & scientific | 2015 |
| Avid Path Ltd | Professional & scientific | 2010 |
| Avinash Menon IO Limited | Administrative & support | 2024 |
| Aviocad Ltd | Administrative & support | 2025 |
| Avipa Properties Ltd | Real estate | 2019 |
| Avocet Resources Limited | Mining & quarrying | 2005 |
| Avonhouse Developments Ltd | Real estate | 2025 |
| Avonmouth Ship Repair Ltd | Administrative & support | 2026 |
| Avrora B Limited | Wholesale & retail | 2020 |
| AW Holdings (Lancashire) Ltd | Real estate | 2020 |
| Aw&J Electrical and Maintenance Limited | Construction | 2019 |
| Awali Limited | Administrative & support | 2007 |
| Award Catering Services Ltd | Hospitality | 2023 |
| Award Marketing Limited | Professional & scientific | 2008 |
| AWB Financial Consultancy Limited | Administrative & support | 2024 |
| AWC IT Consulting Limited | Information & communication | 2019 |
| AWE Developments LLP | | 2007 |
| AWX Services Limited | Real estate | 2019 |
| AX-17-ACE Ltd | Information & communication | 2025 |
| Axel Ltd | Transport & logistics | 2022 |
| Axelle Group Holdings Limited | Financial services | 2024 |
| Axelle Limited | Administrative & support | 2001 |
| AXG CAD Limited | Administrative & support | 2008 |
| Axiom Analytics Limited | Administrative & support | 2013 |
| Axion RAY UK Limited | Information & communication | 2021 |
| Axis Consulting & Design Ltd | Administrative & support | 2007 |
| Axis HR Services Limited | Professional & scientific | 2006 |
| AXL INK Ltd | Arts & recreation | 2025 |
| Axle Bidco Limited | Transport & logistics | 2016 |
| Axle Topco Limited | Financial services | 2016 |
| AXX Logistics Ltd | Other services | 2024 |
| AY Engineering Ltd | Administrative & support | 2026 |
| AY Software Limited | Information & communication | 2010 |
| Ayas Infotech Ltd | Information & communication | 2025 |
| Ayaz (NW) Ltd | Hospitality | 2019 |
| AYC Adhd Assessment and Support Services Ltd | Health & social care | 2025 |
| AYC Psychology and Assessment Services Ltd. | Other services | 2016 |
| Ayilma Limited | Real estate | 2025 |
| AYN Boutique Ltd | Wholesale & retail | 2024 |
| Ayon Nursery Schools Limited | Education | 2021 |
| Aysgarth 01 Ltd | Administrative & support | 2020 |
| Aytech Ltd | Professional & scientific | 2013 |
| AZ Car Transport & Recovery Services Ltd | Transport & logistics | 2026 |
| AZ Europa Trans Limited | Transport & logistics | 2024 |
| AZ Fiber Limited | Extraterritorial | 2012 |
| AZ Floor Fitters Ltd | Construction | 2020 |
| AZ Global Goods Ltd | Wholesale & retail | 2026 |
| AZ Technology Ltd | Information & communication | 2015 |
| Azamour Solutions Limited | Information & communication | 2001 |
| Azarel Property Company Limited | Real estate | 2024 |
| Azelea Care Solutions Ltd | Hospitality | 2020 |
| Azlan Automation Ltd | Information & communication | 2025 |
| Azoria Capital Bidco 3 Limited | Professional & scientific | 2023 |
| Azoria Capital Holdco 3 Limited | Professional & scientific | 2023 |
| Azoria Capital Limited | Professional & scientific | 2020 |
| Azra Gifts Ltd | Wholesale & retail | 2026 |