| Armitage Projects Limited | Information & communication | 2013 |
| Armorgard Group Holdings Limited | Financial services | 2024 |
| Armorgard Holdings Limited | Financial services | 2017 |
| Armorgard Limited | Manufacturing | 2013 |
| Armorive Limited | Manufacturing | 2024 |
| Armthorpe Specsavers Limited | Wholesale & retail | 2017 |
| Arndale Specsavers Limited | Wholesale & retail | 1995 |
| Arndale Visionplus Limited | Wholesale & retail | 1995 |
| Arnison Specsavers Hearcare Limited | Wholesale & retail | 2019 |
| Arnison Specsavers Limited | Wholesale & retail | 2019 |
| Arnold Specsavers Hearcare Limited | Wholesale & retail | 2013 |
| Arnold Specsavers Limited | Wholesale & retail | 1986 |
| Arnold Visionplus Limited | Wholesale & retail | 1999 |
| Arnolds Eyecare Ltd | Wholesale & retail | 2024 |
| Arnolds Group Holdings Limited | Financial services | 2020 |
| Arnolds Opticians Limited | Wholesale & retail | 2009 |
| Arnskee & Co Limited | Financial services | 2024 |
| Arnskii & Co Ltd | Administrative & support | 2024 |
| Aroy Thai Limited | Hospitality | 2024 |
| ARP Pygalls Taxis & Private Hire Ltd | Transport & logistics | 2026 |
| Array Impress Ltd | Professional & scientific | 2024 |
| Arrows Removals of London Limited | Transport & logistics | 2000 |
| Art and Photo Printing Limited | Manufacturing | 2018 |
| Art of Integration Maintenance Ltd | Construction | 2020 |
| Art Regard Ltd | Information & communication | 2025 |
| Artcycle MB C.I.C. | Education | 2024 |
| Artemis Resolutions Ltd | Administrative & support | 2024 |
| Artemis Training and Consultancy Limited | Households | 2004 |
| Arthur Charles Limited | Wholesale & retail | 2018 |
| Arthur Daley’S Scooter Lock UP Ltd | Real estate | 2023 |
| Arthur Daniels & Company Limited | Professional & scientific | 2018 |
| Arthur J Hawke Ltd. | Wholesale & retail | 2016 |
| Artibod Limited | Information & communication | 2009 |
| Artisan Environmental Limited | Professional & scientific | 2005 |
| Artisan Surveyors Limited | Extraterritorial | 2020 |
| Artworx | Education | 2019 |
| Arundel and South Downs Renovations Limited | Construction | 2014 |
| Arundel Plumbing & Heating Ltd | Construction | 2016 |
| Arundel Street Developments LLP | | 2007 |
| Arundel Street Management Limited | Households | 2019 |
| Aruvo Property Limited | Real estate | 2025 |
| ARX Protect Limited | Professional & scientific | 2025 |
| Arxsis Ltd | Administrative & support | 2014 |
| AS Medicare Limited | Health & social care | 2024 |
| Asap Consultancy and Training Limited | Professional & scientific | 2014 |
| ASC Air Conditioning & Refrigeration Limited | Construction | 2019 |
| Ascenti Health Limited | Health & social care | 1996 |
| Ascenti Physio Limited | Health & social care | 2002 |
| Ascenti Wellbeing Limited | Extraterritorial | 2017 |
| Ascentia Mortgage Solutions Limited | Financial services | 2016 |
| Ascia Construction Limited | Construction | 2016 |
| Ascia Holdings Limited | Financial services | 2017 |
| Asecity Ltd | Wholesale & retail | 2024 |
| Asfi Properties Ltd | Construction | 2022 |
| ASH Endeavours Limited | Transport & logistics | 2016 |
| ASH Ohri Consulting Ltd | Professional & scientific | 2026 |
| ASH Wireless Electronics Limited | Professional & scientific | 2001 |
| Ashbourne Derby Specsavers Limited | Wholesale & retail | 2017 |
| Ashby DE LA Zouch Specsavers Hearcare Limited | Wholesale & retail | 2024 |
| Ashby DE LA Zouch Specsavers Limited | Wholesale & retail | 2009 |
| Ashby MOT & Service Centre Limited | Wholesale & retail | 2019 |
| Ashdale Land and Property Company Limited | Construction | 1949 |
| Ashdown Marine Limited | Manufacturing | 2011 |
| Ashenhouse Ltd | Administrative & support | 2025 |
| Ashford Specsavers Hearcare Limited | Wholesale & retail | 2006 |
| Ashford Specsavers Limited | Wholesale & retail | 1995 |
| Ashford Visionplus Limited | Wholesale & retail | 1995 |
| Ashington Specsavers Limited | Wholesale & retail | 2003 |
| Ashley Barker Coaching Ltd | Arts & recreation | 2019 |
| Ashley Sturman Construction Ltd | Construction | 2024 |
| Ashley Young Holdings Limited | Hospitality | 2018 |
| Ashmill Properties Limited | Real estate | 2024 |
| Ashmor Ltd | Real estate | 2022 |
| Ashton in Makerfield Specsavers Limited | Wholesale & retail | 2018 |
| Ashton-Under-Lyne Specsavers Hearcare Limited | Wholesale & retail | 2013 |
| Asia Kitchen Whiteley Ltd | Hospitality | 2023 |
| Asian Voyages Limited | Administrative & support | 2017 |
| Asilomar Limited | Wholesale & retail | 2017 |
| ASJ Partnership Ltd | Transport & logistics | 2025 |
| Askham Magic Productions Limited | Arts & recreation | 2017 |
| Aspect Vision Holdings Limited | Administrative & support | 1997 |
| Aspen Waite Food Limited | Wholesale & retail | 2020 |
| Aspera Recruitment Ltd | Administrative & support | 2022 |
| Aspire Business Consultancy Holdings Limited | Real estate | 2025 |
| Aspire-Services Ltd. | Construction | 2013 |
| Asrs (Fareham) Ltd | Wholesale & retail | 2005 |
| Asrs Preservation Ltd | Construction | 2008 |
| Assimilate Learning Limited | Other services | 2019 |
| Associated Cleaning Services Limited | Professional & scientific | 2002 |
| Associated Quality Services Ltd | Construction | 2011 |
| Associated Rework Solutions Limited | Other services | 2017 |
| Assured (UK) Limited | Other services | 2007 |
| Aster Prime Limited | Wholesale & retail | 2025 |
| Asterion Strategic Ltd | Professional & scientific | 2025 |
| Astor Defence Limited | Administrative & support | 2023 |
| Astor House (Torquay) Management Company Limited | Real estate | 2008 |
| Astor International Limited | Manufacturing | 2020 |
| Astor Logistics Ltd | Transport & logistics | 2025 |
| Astor Property Limited | Real estate | 2023 |
| Astra Lumen Images Ltd | Information & communication | 2025 |