| Alto People Ltd | Administrative & support | 2026 |
| Alturacode Ltd | Information & communication | 2026 |
| Alves Engineering Consultants Limited | Professional & scientific | 2019 |
| Always Alert Security Ltd | Administrative & support | 2025 |
| Always Cleaned Limited | Administrative & support | 2021 |
| AM Validation Services Ltd | Administrative & support | 2024 |
| AMA Pro Builders Limited | Construction | 2026 |
| Amaala Properties Limited | Real estate | 2024 |
| Amack Ltd | Professional & scientific | 2013 |
| Amack Properties Ltd | Real estate | 2022 |
| Amaha WE Uganda (UK). | Health & social care | 2012 |
| Aman Ruprah Ltd. | Health & social care | 2011 |
| Amanah Corp Ltd | Households | 2024 |
| Amare Limited | Professional & scientific | 2013 |
| Amaxuk Ltd | Professional & scientific | 2022 |
| Amber Dog Limited | Information & communication | 2019 |
| Amber Employment Services Ltd | Administrative & support | 2007 |
| Amber Technical Solutions Ltd | Professional & scientific | 2010 |
| Ambili Ltd | Other services | 2018 |
| Ambrose Koffee Ltd | Hospitality | 2021 |
| Ambrose Bakery Ltd | Manufacturing | 2022 |
| Ambrosia London Ltd | Wholesale & retail | 2025 |
| AMC Design& Build Ltd | Construction | 2025 |
| AMC Express Limited | Transport & logistics | 2003 |
| AMC Financial Services Limited | Professional & scientific | 2022 |
| AMC8 Properties Ltd | Real estate | 2026 |
| Amco Corporate Services Limited | Other services | 2019 |
| AMD Technik (UK) Limited | Manufacturing | 2008 |
| Amera Shankla HMU Ltd | Other services | 2026 |
| Amerisourcebergen International Technology Services Limited | Information & communication | 2021 |
| Ameth Hospitality Ltd | Hospitality | 2026 |
| Amezinggrace Care Limited | Health & social care | 2022 |
| AMF27 Consulting Ltd | Professional & scientific | 2025 |
| Amia Limited | Health & social care | 2024 |
| Amico Labs Ltd. | Information & communication | 2009 |
| Amily Homecare Ltd | Health & social care | 2015 |
| Amirani Limited | Professional & scientific | 2011 |
| Amishane Limited | Other services | 2002 |
| AMK Designs Ltd | Construction | 2017 |
| Ammar & Co Properties Ltd | Real estate | 2024 |
| Ammar Homes Ltd | Real estate | 2017 |
| Ammis Limited | Real estate | 2001 |
| AMP Consultancy Services Ltd | Information & communication | 2024 |
| Ampe Trading UK Limited | Wholesale & retail | 2015 |
| AMR Partners Limited | Wholesale & retail | 2025 |
| Amsi Rail Ltd | Construction | 2017 |
| Amusico Limited | Administrative & support | 2004 |
| Amzo Consulting Ltd | Professional & scientific | 2011 |
| Anaid Ltd | Administrative & support | 2018 |
| Analysr Ltd | Information & communication | 2015 |
| Anand Properties Ltd | Real estate | 2021 |
| Anaylin Limited | Information & communication | 2014 |
| Anazao | Professional & scientific | 2009 |
| Anchor Crescent Ltd | Wholesale & retail | 2024 |
| Anchor Events Limited | Hospitality | 2011 |
| Anchor Property Maintenence Ltd | Real estate | 2025 |
| Anchortag Ltd | Manufacturing | 2025 |
| AND a Movie Ltd | Information & communication | 2024 |
| Anderson Firmin & Collins Limited | Wholesale & retail | 1946 |
| Anderson Young Aviation Limited | Administrative & support | 2015 |
| Andre Peers Consulting Ltd | Professional & scientific | 2023 |
| Andrei Garage Ltd | Wholesale & retail | 2017 |
| Andreia Trigo Consulting Ltd | Health & social care | 2017 |
| Andrews Consulting (Surrey) Limited | Professional & scientific | 2007 |
| Andripopa Ltd | Transport & logistics | 2016 |
| Andsug Limited | Professional & scientific | 2018 |
| Andy Major Design Limited | Professional & scientific | 2010 |
| Andy Marshall Services Limited | Education | 2013 |
| Andy Skilton Engineers Limited | Manufacturing | 2008 |
| Anerley Executor & Trustee Company Limited | Financial services | 1994 |
| Aneta Transport Ltd | Transport & logistics | 2023 |
| Angabit Ltd | Information & communication | 2015 |
| Angel Cars (Woking) Ltd | Transport & logistics | 2015 |
| Angela LEE (Audit & Accountancy Services ) Limited | Professional & scientific | 2013 |
| Angelic Network Community Interest Company | Public administration | 2020 |
| Angels Associates Ltd | Hospitality | 2021 |
| Angle Associates Limited | Professional & scientific | 2014 |
| Angle Investments Ltd | Real estate | 2025 |
| Anglo-Swedish House Limited | Real estate | 1990 |
| Angra Invest Ltd | Professional & scientific | 2020 |
| Angry Panda Productions Limited | Information & communication | 2015 |
| Animade AI Ltd | Information & communication | 2024 |
| Anjm Express Ltd | Transport & logistics | 2024 |
| Ankerwycke Properties Limited | Real estate | 2021 |
| Anne Engstrom Limited | Professional & scientific | 2024 |
| Annie Rose PT Limited | Arts & recreation | 2026 |
| Ansell Enterprises Limited | Real estate | 1993 |
| Anson House Ltd | Professional & scientific | 2025 |
| Anthony Lawrence Ltd | Construction | 2024 |
| Antler Social Ltd | Professional & scientific | 2021 |
| Antra Holdings Ltd | Financial services | 2022 |
| Anzos Sportswear Ltd | Wholesale & retail | 2025 |
| Ao-Digital Ltd | Professional & scientific | 2019 |
| AOA Cars Ltd | Transport & logistics | 2026 |
| AOL Consulting Ltd | Professional & scientific | 1997 |
| AOL Corporate Events Limited | Administrative & support | 1997 |
| AP Digital Consulting Ltd | Professional & scientific | 2014 |
| AP Stays and Manage Ltd | Real estate | 2025 |
| Apark & Hobbs Roofing Limited | Construction | 2019 |
| APE Properties Limited | Real estate | 2005 |