| Altius Scaffolding Limited | Administrative & support | 2018 |
| Aluminium Warehouse Limited | Wholesale & retail | 2010 |
| Alutek Constructions Ltd | Construction | 2022 |
| Always RAW Pet Supplies Ltd | Wholesale & retail | 2023 |
| AM Planning Trustees Limited | Administrative & support | 2021 |
| AM Property Specialists Ltd | Other services | 2017 |
| AM Safety Specialists Limited | Extraterritorial | 2012 |
| AM Specialists Group Limited | Professional & scientific | 2005 |
| AM Training Specialists Limited | Other services | 2012 |
| AMA Properties Group Ltd | Real estate | 2024 |
| AMA Security Limited | Administrative & support | 2018 |
| Amago Kitchen Ltd | Hospitality | 2023 |
| Amanda Clark Arts Ltd | Arts & recreation | 2020 |
| Amanda Design Ltd | Professional & scientific | 2012 |
| Amaniki Limited | Financial services | 2019 |
| Amazed Group Ltd | Wholesale & retail | 2023 |
| Ambiance Enterprise Limited | Hospitality | 2017 |
| Amed Enterprise Ltd | Other services | 2019 |
| Amls Fleet Services Ltd | Other services | 2025 |
| Ammys Store Braintree Ltd | Wholesale & retail | 2025 |
| Amos Automation Services Ltd | Professional & scientific | 2022 |
| Amos Solutions Ltd | Administrative & support | 2025 |
| Ampacity Electrical Installation Ltd | Construction | 2023 |
| Amplight Ltd | Construction | 2026 |
| Amwell Court Management Limited | Households | 1983 |
| Amys Pet Supplies Ltd | Wholesale & retail | 2022 |
| AN Desserts Ltd | Hospitality | 2023 |
| Anchor Financial Operations Limited | Professional & scientific | 2026 |
| Ancient District Limited | Administrative & support | 2018 |
| Ancolies Ltd | Construction | 2023 |
| Anderson Contract Fixing Limited | Construction | 2013 |
| Andi's Valeting Ltd | Wholesale & retail | 2024 |
| Andre Clark Consulting Ltd | Professional & scientific | 2015 |
| Andrew Martin - Planning Ltd | Professional & scientific | 2012 |
| Andrew Pipe Associates Limited | Professional & scientific | 2003 |
| Andrew ROY Smith Limited | Real estate | 2016 |
| Andrews Lane Management Company Limited | Households | 1983 |
| Andrewsfield Aviation Maintenance Ltd | Manufacturing | 2015 |
| Andy Barnes Services Ltd | Manufacturing | 2015 |
| Andy Meech Landscape and Fencing Limited | Administrative & support | 2003 |
| Angelo Summer Ltd | Hospitality | 2023 |
| Anglais Catering Ltd | Hospitality | 2022 |
| Anglia Compliance & Training Ltd | Transport & logistics | 2013 |
| Anglia Courier Express (East Anglia) Limited | Transport & logistics | 2005 |
| Anglia Fire Alarms Limited | Extraterritorial | 2004 |
| Anglia Fire Protection Limited | Extraterritorial | 1992 |
| Anglia Forwarding Group Limited | Financial services | 2010 |
| Anglo Holdings Ltd | Construction | 2025 |
| Aniche Venetian Ltd | Construction | 2024 |
| Anness Publishing Limited | Information & communication | 1989 |
| Ansell Carpentry Limited | Construction | 2017 |
| Anthony Andrews Carpentry Ltd | Construction | 2018 |
| Anthony Bishop Limited | Administrative & support | 1997 |
| Anthony Russel Group Limited | Financial services | 2023 |
| Anthony Russel Limited | Professional & scientific | 1999 |
| Anthony Russell Limited | Extraterritorial | 2009 |
| Antonov Ltd | Hospitality | 2025 |
| Apatchy Limited | Wholesale & retail | 2014 |
| Apex Grace Heritage Limited | Wholesale & retail | 2021 |
| Apex Innovations (New Builds) Limited | Construction | 2018 |
| Apex Innovations Ltd | Construction | 2015 |
| Apex Landscaping & Garden Design Ltd | Administrative & support | 2022 |
| Apex Vehicle Sales Ltd | Wholesale & retail | 2021 |
| APM Homes Limited | Construction | 2017 |
| Apogee Aviation Services Ltd | Education | 2018 |
| Apollo Glass Ltd | Construction | 2024 |
| APS Welding Services Ltd | Other services | 2025 |
| Aquabathe Ltd | Wholesale & retail | 2024 |
| Aquanissos Limited | Wholesale & retail | 2020 |
| Arda Kebab Ltd | Wholesale & retail | 2018 |
| Arden Film Co. Limited | Information & communication | 2026 |
| Ariosa Active Limited | Wholesale & retail | 2026 |
| ARK Care Solutions Ltd | Administrative & support | 2026 |
| Armill Holdings Limited | Financial services | 2025 |
| Armill Lift Trucks Limited | Administrative & support | 1998 |
| Arnet IT Solutions Ltd | Information & communication | 2010 |
| Arnold Installations Ltd | Construction | 2025 |
| Aromaherb Limited | Manufacturing | 1996 |
| Arrow Tyres Limited | Wholesale & retail | 2002 |
| Art by Holy Moly Limited | Arts & recreation | 2019 |
| Art of Arts (U.K.) Limited | Professional & scientific | 1987 |
| Arthur Brett & Sons Limited | Manufacturing | 2008 |
| Artistry Plastics Ltd | Other services | 2014 |
| Artoria Tattoos Ltd | Professional & scientific | 2025 |
| Arts International Performing Arts Limited | Education | 2023 |
| Artura Funding Solutions Ltd | Financial services | 2020 |
| Artura Salvage Solutions Ltd | Wholesale & retail | 2020 |
| AS Food Private Ltd | Hospitality | 2026 |
| ASA Mouldings Ltd | Construction | 2026 |
| Ashby Court (Hoddesdon) Management Limited | Households | 2010 |
| Ashcread Limited | Construction | 2002 |
| Ashden Accountants Limited | Professional & scientific | 2023 |
| Ashden Heycroft Limited | Extraterritorial | 2017 |
| Ashdown Developments Ltd | Construction | 2018 |
| Ashleys of Frinton Limited | Wholesale & retail | 2012 |
| Ashton Associates (GB) Limited | Manufacturing | 2003 |
| Ashton Security Ltd | Administrative & support | 2017 |
| ASJ Transport Limited | Transport & logistics | 2016 |
| ASL Drive Limited | Transport & logistics | 2015 |
| Aspenden Road Management Company Limited | Real estate | 2022 |