| AM Healthcare Solutions Limited | Health & social care | 2019 |
| AM Technical Consulting Ltd | Professional & scientific | 2026 |
| Amal Controls Ltd | Wholesale & retail | 2018 |
| Ambec Limited | Real estate | 2011 |
| Amberleaze Ltd | Real estate | 2020 |
| Amberley (Tunbridge Wells) Limited | Households | 2006 |
| Ambleford Ltd | Education | 2015 |
| Amboh Properties Limited | Real estate | 1958 |
| Ambre Candles Ltd | Manufacturing | 2024 |
| AMC Contracts Kent Ltd | Construction | 2024 |
| Amcd Consulting Ltd | Professional & scientific | 2016 |
| Amdc Property Limited | Construction | 2013 |
| American International Relocation Solutions UK Limited | Administrative & support | 2014 |
| American Modern Nails Ltd | Other services | 2022 |
| American SAT & ACT Tuition Limited | Education | 2016 |
| Amevic Ltd | Wholesale & retail | 2025 |
| Amfe Agency Ltd | Administrative & support | 2020 |
| Amflex Ltd | Wholesale & retail | 2025 |
| AMG Capital Partners Limited | Financial services | 2001 |
| AMG Print Consultants Ltd | Professional & scientific | 2017 |
| Amhurst Associates Limited | Information & communication | 2021 |
| Amhurst Kitchens Ltd | Wholesale & retail | 2026 |
| AMI Elisah Bridal Ltd | Manufacturing | 2024 |
| Amici DEL Vesuvio Ltd | Hospitality | 2022 |
| Amicus Advisory Limited | Professional & scientific | 2023 |
| Amicus Property Limited | Real estate | 2020 |
| Amig Property Limited | Real estate | 2005 |
| Amity Productions Ltd | Information & communication | 2015 |
| AMK Technologies Limited | Professional & scientific | 2013 |
| Amkk Ltd | Professional & scientific | 2007 |
| AML (Tech) Ltd | Information & communication | 1987 |
| Ammark (UK) Limited | Administrative & support | 2006 |
| Amor Financial Ltd | Financial services | 2017 |
| AMP Infrastructure Ltd | Real estate | 2007 |
| Amplifi Foundation Limited | Other services | 2025 |
| Amplifi.Tw Limited | Other services | 2023 |
| Amplio Capital Ltd | Financial services | 2025 |
| Amrosoft Ltd. | Information & communication | 2018 |
| Amrutha Properties Limited | Real estate | 2025 |
| Amsie Limited | Real estate | 2017 |
| Amtw Hospitality Ltd | Hospitality | 2022 |
| Amullinger Limited | Professional & scientific | 2016 |
| AMX Recruitment Limited | Other services | 2024 |
| Amybagha Consultancy Ltd | Health & social care | 2021 |
| Anarai Ltd | Construction | 2025 |
| Anazo Ltd | Professional & scientific | 2025 |
| Anchor Build Limited | Construction | 2023 |
| AND SEW to Keep Ltd | Wholesale & retail | 2018 |
| Andd Creative Limited | Professional & scientific | 2020 |
| Anderson John Consulting Limited | Professional & scientific | 2024 |
| Andlib Cleaning Ltd | Administrative & support | 2023 |
| Andree Associates Limited | Professional & scientific | 2006 |
| Andreispeter Ltd | Transport & logistics | 2024 |
| Andrew Hancock Actuarial Ltd | Financial services | 2023 |
| Andrew Harrison & Sons Limited | Other services | 2018 |
| Andrew Hunter Consultancy Ltd | Professional & scientific | 2022 |
| Andrew Jacobs (UK) Limited | Financial services | 2010 |
| Andrew Jacobs LLP | | 2010 |
| Andrew Saunders Engineering Ltd | Professional & scientific | 2016 |
| Andrew Spencer Ltd | Information & communication | 2017 |
| Andrew Wenham Limited | Administrative & support | 2024 |
| Angel Court Management Limited | Real estate | 2009 |
| Angelfish Limited | Administrative & support | 1994 |
| Angell Productions Limited | Information & communication | 2009 |
| Anger Heritage Limited | Real estate | 2004 |
| Anglearc Ltd | Information & communication | 2023 |
| Anglo Management Music Ltd | Information & communication | 1997 |
| Anglo Mexican Marine Insurance Services Limited | Financial services | 2002 |
| Anglo-Overseas Consultants Limited | Professional & scientific | 1993 |
| Anglolat London Investors LLP | | 2013 |
| Anglolat Manchester Limited | Real estate | 2017 |
| Anglolat Real Estate and Hospitality Investments Limited | Financial services | 2021 |
| Angu Client Services Limited | Information & communication | 2018 |
| Angu Grain Services Limited | Information & communication | 2018 |
| Angus Energy Enterprises Limited | Professional & scientific | 2024 |
| Anisa Property Ltd | Real estate | 2023 |
| Anna Scott Productions Ltd | Arts & recreation | 2026 |
| Anne Education Ltd | Education | 2023 |
| Anorak Digital Ltd | Professional & scientific | 2021 |
| Anorakcreative Limited | Professional & scientific | 2010 |
| Antalia Limited | Real estate | 2025 |
| Anthony Mason Construction Ltd | Construction | 2019 |
| Anytime Anywhere Signs & Installations Limited | Administrative & support | 2017 |
| AOJ Properties Limited | Real estate | 2018 |
| AOR Boyne Park Limited | Real estate | 2026 |
| AOY Properties Ltd | Construction | 2025 |
| Aparna Mishra Limited | Information & communication | 2019 |
| Apeldale Limited | Extraterritorial | 1947 |
| Apex Design and Build (Southern) Ltd | Construction | 2023 |
| Apex Engineering Contractors Ltd | Professional & scientific | 2023 |
| Apex Masonry Limited | Manufacturing | 1990 |
| Apex Services Kent Limited | Transport & logistics | 2019 |
| Apfen Associates Ltd | Professional & scientific | 2012 |
| Aphelion Capital Ltd | Financial services | 2025 |
| APL GAS and Heating Services Ltd | Construction | 2021 |
| Apple Tree Purchase and Sales Limited | Wholesale & retail | 2021 |
| Applefield Homes Limited | Real estate | 2011 |
| Applewood Building Services Ltd | Construction | 1998 |
| Applied Organisational Evolution Ltd | Professional & scientific | 2026 |
| Appu Limited | Health & social care | 2008 |