| Amal Care Solutions Ltd | Health & social care | 2022 |
| AMB Lifting Ltd | Construction | 2014 |
| Amber Printwork Limited | Manufacturing | 1955 |
| Amlex Management Ltd | Real estate | 2024 |
| Amlex Property Limited | Real estate | 2019 |
| Anberco Limited | Other services | 2018 |
| Anchortech Solutions Ltd | Information & communication | 2026 |
| Andec Solutions Limited | Construction | 2009 |
| Anderson Burgess Ltd | Professional & scientific | 2026 |
| Andrea Ives Consulting Ltd | Professional & scientific | 2013 |
| Andrew Gray & Associates Limited | Financial services | 2019 |
| Andrew Hall Cricket Limited | Education | 2023 |
| Andrews Building Company Limited | Construction | 2003 |
| Aneta Pile Ecommerce & Digital Strategy Ltd | Professional & scientific | 2026 |
| Ange Creations Ltd | Health & social care | 2022 |
| Anjuna Estates Limited | Real estate | 2021 |
| Anker International P L C | Extraterritorial | 1978 |
| ANS Lighting Limited | Professional & scientific | 2013 |
| Antarya Ltd | Wholesale & retail | 2025 |
| Anthony Rigby Holdings Limited | Real estate | 2021 |
| Antiques on High Harrogate Ltd | Real estate | 2023 |
| Antiques on High Limited | Real estate | 1997 |
| Antiques on High Taunton Ltd | Wholesale & retail | 2022 |
| AO Building Services MK Ltd | Construction | 2025 |
| Apexbuild Solutions Limited | Construction | 2025 |
| Apiro UK Limited | Professional & scientific | 2018 |
| Appia Europe Limited | Financial services | 2008 |
| Applegreen Electric UK Holdings Limited | Financial services | 2023 |
| Applegreen Electric UK Limited | Energy | 2021 |
| Applegreen Electric UK Service Areas Limited | Energy | 2022 |
| Aquause Limited | Professional & scientific | 2021 |
| Arcade Eight Piercing Limited | Other services | 2022 |
| Archway Construction (Northants) Ltd | Construction | 2013 |
| Archway Developments (2) Limited | Other services | 2019 |
| Archway Developments (3) Limited | Other services | 2019 |
| Archway Developments (4) Limited | Construction | 2021 |
| Archway Developments (5) Limited | Construction | 2021 |
| Archway Developments (6) Limited | Construction | 2021 |
| Archway Developments (8) Ltd | Construction | 2020 |
| Archway Developments (9) Limited | Real estate | 2025 |
| Archway Group Investments Limited | Real estate | 2020 |
| Archway Northampton Limited | Construction | 2017 |
| Argan Care & Support Group Ltd | Health & social care | 2025 |
| Argan Training Solutions Limited | Education | 2023 |
| Armstrong Media Group Limited | Professional & scientific | 2022 |
| Arumi Analytics Limited | Information & communication | 2014 |
| Arundel Court (Astwood) Management Company Ltd | Households | 2023 |
| ASH Interiors Ltd. | Wholesale & retail | 2003 |
| Ashley and Phoebe Limited | Real estate | 2010 |
| Ashraf M LLP | | 2026 |
| Ashridge Gardens (Wootton) Management Company Ltd | Households | 2025 |
| Ashturn Logistics Ltd | Transport & logistics | 2023 |
| ASK Real Estate Services Ltd | Real estate | 2025 |
| Askpinpoint Limited | Extraterritorial | 2020 |
| Assure Properties (UK) Limited | Real estate | 2006 |
| Aston Networks Limited | Professional & scientific | 2019 |
| Aston Security Ltd | Administrative & support | 2024 |
| Aston Trio Limited | Administrative & support | 2010 |
| Astons Estate Agents (MK) Ltd | Real estate | 2009 |
| Astons Financial Services LLP | | 2011 |
| Astra Brokers Ltd | Professional & scientific | 2025 |
| Astrum Homes Limited | Real estate | 2018 |
| Astrum Homes MK Ltd | Construction | 2021 |
| Atrb Ltd | Administrative & support | 2019 |
| Atxr Ltd | Information & communication | 2025 |
| Audio Visual Network Sales, Installation & Service Limited | Wholesale & retail | 2014 |
| Audit Limited | Professional & scientific | 2013 |
| Aurion Solar Limited | Energy | 2025 |
| Auriprax Ltd | Information & communication | 2026 |
| Aurora Advisory Group Ltd | Professional & scientific | 2023 |
| Aurora Forensic Consulting Limited | Professional & scientific | 2023 |
| Austen & Pennifold Construction Limited | Construction | 2018 |
| Auto Service Solutions Limited | Wholesale & retail | 2009 |
| Auto Service Solutions MK Limited | Wholesale & retail | 2019 |
| Autoneura Ltd | Professional & scientific | 2022 |
| Autovista Trading Limited | Wholesale & retail | 2025 |
| Avilon Ltd | Real estate | 2020 |
| Avse Property Limited | Real estate | 2025 |
| Avvio AI Limited | Wholesale & retail | 2025 |
| Avya Consultancy Limited | Information & communication | 2015 |
| AW GAS & Heating Services Limited | Construction | 2019 |
| Axora Group Ltd | Real estate | 2025 |
| Aylesbury Street Properties Limited | Administrative & support | 2019 |
| Azad Barbers Limited | Other services | 2017 |
| B & T Mcdowells Ltd | Hospitality | 2024 |
| B M Verdant Ltd | Financial services | 2026 |
| B Smart Lettings Limited | Real estate | 2010 |
| B&B Lane Estates Limited | Real estate | 2022 |
| B&C Kebab Limited | Hospitality | 2020 |
| B.K. Pulse Limited | Manufacturing | 1995 |
| Back to Good Ltd | Health & social care | 2022 |
| Badj AM 1 Limited | Financial services | 2025 |
| Badj Cricket Limited | Financial services | 2024 |
| Bagshot Grill Ltd | Hospitality | 2019 |
| Baker Web Design Limited | Information & communication | 2025 |
| Bakesense 2026 Limited | Professional & scientific | 2026 |
| Ball Air Conditioning Services Ltd | Construction | 2020 |
| Bancroft Property Holdings Ltd | Real estate | 2013 |
| Bancroft Property Management Ltd | Real estate | 2018 |
| Banks' Martial Arts Academy Limited | Education | 2016 |