| Amply Creations Ltd | Wholesale & retail | 2019 |
| AMS Porsche Ltd | Wholesale & retail | 2019 |
| AMY Johnson Court Ltd | Real estate | 2017 |
| Anaesphere Limited | Education | 2024 |
| Analytix Consulting Limited | Information & communication | 2006 |
| Anarkik Designs Ltd | Other services | 2021 |
| Anastasia's Cat Hotel Ltd | Hospitality | 2014 |
| ANB Electrical Services Ltd | Construction | 2022 |
| Anchor Hosts Ltd | Real estate | 2026 |
| Anchusa Care Limited | Health & social care | 2016 |
| Ancient Care Limited | Wholesale & retail | 2020 |
| Anderton Toys Limited | Wholesale & retail | 2019 |
| Andrew Burt Associates Limited | Professional & scientific | 2017 |
| Andrew Charles (Watch & Clockmakers) Limited | Other services | 2000 |
| Andrew Hillier Consulting Limited | Professional & scientific | 2012 |
| Andromeda Assets Limited | Financial services | 2020 |
| Andy Mansfield Osteopathy Limited | Health & social care | 2015 |
| Andy Theakstone Studio Ltd | Arts & recreation | 2019 |
| Anew Limited | Extraterritorial | 1999 |
| Angali Shipping & Trading Company Limited | Transport & logistics | 1973 |
| Angel Human Resources Limited | Administrative & support | 1984 |
| Angel Human Resources Managed Services Limited | Administrative & support | 2009 |
| Angel Internet Ltd | Information & communication | 2005 |
| Angle Scaffolding Limited | Construction | 2004 |
| Anglia Motor Sport Club Limited | Other services | 2013 |
| Anglia Seamless Gutters Ltd | Construction | 2021 |
| Anglian Country Inns Limited | Hospitality | 1996 |
| Anglin Developments Limited | Administrative & support | 2019 |
| Anglomar International Limited | Administrative & support | 2020 |
| Angram Accommodation Limited | Real estate | 2025 |
| Angram Property Limited | Real estate | 2025 |
| Angram Trading Limited | Real estate | 2026 |
| Anholt Consulting Limited | Professional & scientific | 2011 |
| Anima Gymnastics Club Ltd | Arts & recreation | 2021 |
| Anisa's Flowers Limited | Wholesale & retail | 2025 |
| Anita Sanford Properties Ltd | Real estate | 2023 |
| Ankabut Ltd | Information & communication | 2006 |
| Anlife Limited | Hospitality | 2007 |
| Anna Collins Projects LLP | | 2017 |
| Anna Hallas Consultancy Services Limited | Administrative & support | 2024 |
| Anna Morrison Consultancy Services Limited | Professional & scientific | 2010 |
| Anne Marie Hair Studio Ltd | Other services | 2020 |
| Annett Analytical Ltd | Professional & scientific | 2020 |
| Annie's Playhouse Limited | Health & social care | 2025 |
| Anpid Ltd | Other services | 2015 |
| Ansel Limited | Transport & logistics | 2019 |
| Ansharf Developments Limited | Construction | 2025 |
| Ansharf Estates Limited | Real estate | 2020 |
| Ansharf General Motors Limited | Wholesale & retail | 2023 |
| Ansharf Holdings Limited | Real estate | 2020 |
| Anthemion Restoration Limited | Construction | 2023 |
| Anthon Compass Care Services Ltd | Health & social care | 2026 |
| Anthony Scaffolding Services Limited | Construction | 2006 |
| Anthoweb Limited | Information & communication | 2015 |
| Antique Tractor Parts Limited | Manufacturing | 2010 |
| Antiques Online Ltd | Wholesale & retail | 1995 |
| Anvil Taverns Ltd | Hospitality | 2026 |
| Anvillabs Ltd | Information & communication | 2024 |
| Aodan's Driving Services Limited | Transport & logistics | 2014 |
| APC Capital Holdings Limited | Financial services | 2021 |
| APEX888 Limited | Financial services | 2026 |
| Apitura Innovation Limited | Professional & scientific | 2024 |
| APL Property Services Limited | Construction | 2020 |
| Apple Trees, Hitchin (Maintenance) Limited | Households | 1976 |
| Appleton Brooks Ltd | Wholesale & retail | 2022 |
| Application Management Limited | Information & communication | 2024 |
| Applied Geotechnical Engineering Ltd | Professional & scientific | 2025 |
| Appltec Ltd | Other services | 2023 |
| Apprenticeship People Ltd | Education | 2025 |
| Apres Haus Ltd | Wholesale & retail | 2025 |
| Aprex Foods Limited | Hospitality | 2021 |
| Aqualite LLP | | 2022 |
| Aquamoni UK Ltd | Water & waste | 2024 |
| Aquila Legal Limited | Professional & scientific | 2023 |
| AR Prop Serv Ltd | Construction | 2026 |
| ARA Real Estate Investments Limited | Real estate | 2021 |
| Aramis Investments (Bath) Limited | Real estate | 2021 |
| Arbaniya Ltd. | Financial services | 2012 |
| Arcangel Consultancy Limited | Information & communication | 2007 |
| Arcangel Limited | Manufacturing | 1999 |
| Arch-Con Limited | Construction | 2016 |
| Archer Homes Limited | Real estate | 2019 |
| Archie Patterson Limited | Professional & scientific | 2025 |
| Architecture London Ltd | Professional & scientific | 2015 |
| Archwood Systems Limited | Information & communication | 2013 |
| Arciv Limited | Arts & recreation | 2021 |
| Arden Care UK Ltd | Real estate | 2022 |
| Arden House Nursing and Care Ltd | Health & social care | 2022 |
| Areli International Holdings (UK) Limited | Professional & scientific | 2019 |
| Arema Farms Limited | Extraterritorial | 1978 |
| Arena Security Limited | Administrative & support | 1984 |
| Arganese Investments Limited | Professional & scientific | 2023 |
| Argn Construction Ltd | Construction | 2023 |
| Argn Property Ltd | Construction | 2025 |
| Argon Utility Infrastructure Ltd | Energy | 2021 |
| Ariaca Ltd | Health & social care | 2022 |
| Arise Recruit Limited | Administrative & support | 2024 |
| Aristeon Growth Limited | Administrative & support | 2024 |
| Armada Property Group Limited | Construction | 2016 |
| Armas DE LOS Reyes Bucklersbury Limited | Hospitality | 2024 |