| AMH Test Systems Limited | Information & communication | 2012 |
| Amharic Ventures Ltd | Wholesale & retail | 2026 |
| Amheli Services Ltd | Professional & scientific | 2014 |
| Amies Electrical Ltd | Construction | 2020 |
| Amigo Universal Limited | Information & communication | 2024 |
| Amigos OFF Licence UK Limited | Hospitality | 2009 |
| Amii Harwood Artist Limited | Arts & recreation | 2024 |
| Amik Ltd | Health & social care | 2024 |
| Amika Boutique Limited | Wholesale & retail | 2017 |
| Amins Chelmsford Ltd | Health & social care | 2021 |
| Amiram Ltd | Transport & logistics | 2018 |
| Amis Development Co. Limited | | 1983 |
| Amisoft Technologies Limited | Information & communication | 2001 |
| Amjosa Limited | Financial services | 2016 |
| Amjosa Limited Partnership | | 2016 |
| Amjosa Partnership (GP) Limited | Financial services | 2016 |
| AMK Decores Ltd | Construction | 2025 |
| Amlib Aviation Limited | Manufacturing | 2012 |
| Ammolite Capital Limited | Professional & scientific | 2019 |
| Amohelang Limited | Health & social care | 2024 |
| Amor Design & Build Ltd. | Construction | 2023 |
| Amore Lettings Ltd | Real estate | 2022 |
| AMP Accountancy Limited | Professional & scientific | 2024 |
| AMP Enterprises (UK) Ltd | Wholesale & retail | 2013 |
| Ampleoffice Limited | Professional & scientific | 1995 |
| Amplified Robot Limited | Administrative & support | 2013 |
| Amplify Digital Consultancy Ltd | Information & communication | 2026 |
| Amplifyathlete Limited | Other services | 2025 |
| Ampliwave Ltd | Wholesale & retail | 2017 |
| AMR Property Developments Ltd | Construction | 2013 |
| AMS CAD Limited | Professional & scientific | 1998 |
| AMS Investments and Property Ltd | Real estate | 2021 |
| Amsc Leisure Ltd | Hospitality | 2022 |
| Amsik 2023 Ltd | Health & social care | 2023 |
| Amsterisk Limited | Information & communication | 2011 |
| AMW Services Enterprise Limited | Education | 2025 |
| AMW1810 Consulting Limited | Professional & scientific | 2017 |
| AMY Burger Surgery Ltd | Health & social care | 2023 |
| AMY H Baker Property Limited | Real estate | 2026 |
| AMY Thirkettle Ltd | Wholesale & retail | 2020 |
| Amyconroy Limited | Other services | 2023 |
| Amyhana Consultancy Limited | Professional & scientific | 2022 |
| Amzel Limited | Administrative & support | 2003 |
| Anagha Technosoft Ltd | Information & communication | 2024 |
| Analoguebooks Ltd | Wholesale & retail | 2024 |
| Analyisport Limited | Education | 2021 |
| Ananta Aeon Limited | Wholesale & retail | 2025 |
| Ananta Convenience Limited | Wholesale & retail | 2024 |
| Anantya Group Limited | Hospitality | 2024 |
| Anantya Trade Ltd | Wholesale & retail | 2025 |
| Anashwara Ltd | Wholesale & retail | 2025 |
| Anass Yakubu Ltd | Health & social care | 2019 |
| Anbela Limited | Information & communication | 2025 |
| Anchinous Labs Limited | Information & communication | 2026 |
| Anchor Estates Norfolk Ltd | Real estate | 2026 |
| Anchor Homes Ltd | Construction | 2005 |
| Anchor House Residents Limited | Households | 2002 |
| Anchor Mews Limited | Real estate | 2002 |
| Anchorage Capital Limited | Financial services | 2013 |
| Anchorage Securities Limited | Real estate | 2014 |
| Anchorwin Limited | Administrative & support | 2004 |
| Anders Property Solutions Ltd | Real estate | 2023 |
| Anderson Refurbishments Ltd. | Construction | 2018 |
| Anderson Surveyors Ltd | Professional & scientific | 2019 |
| Anderson's (Menswear) Limited | Wholesale & retail | 1977 |
| Andersons Services and Supplies Limited | Manufacturing | 2011 |
| Anderton Quantity Surveyors Ltd | Construction | 2004 |
| Andrea Finegan Ltd | Professional & scientific | 2011 |
| Andrea Kirkham Conservation Ltd | Professional & scientific | 2014 |
| Andree Elizabeth Ltd | Other services | 2012 |
| Andrew Bryan Sexton Limited | Extraterritorial | 2025 |
| Andrew Butcher Ltd | Professional & scientific | 2013 |
| Andrew Masdin Consulting Ltd | Administrative & support | 2006 |
| Andrew Mason Ltd | Professional & scientific | 2014 |
| Andrew Parker Associates Limited | Professional & scientific | 2010 |
| Andrew Paul Furniture Ltd | Manufacturing | 2010 |
| Andrew Savory Dental Laboratory Limited | Manufacturing | 2003 |
| Andrew Shooter Ltd | Construction | 2012 |
| Andrew Smith Consultancy Limited | Professional & scientific | 2007 |
| Andrew Smith Enterprises Limited | Wholesale & retail | 2009 |
| Andrew Thompson & Associates Ltd | Financial services | 2010 |
| Andrew Thompson 1967 Ltd | Financial services | 2024 |
| Andro IT Limited | Information & communication | 2025 |
| Ands 1997 Ltd | Transport & logistics | 2026 |
| Andy Daniels Ltd | Construction | 2015 |
| Andy Durrant Builders Ltd | Construction | 2003 |
| Andy Knott Construction Limited | Construction | 2003 |
| Andy Manship Plastering Ltd | Construction | 2019 |
| Andy Prior Design Ltd | Information & communication | 2013 |
| Andy Thompson Security Services Limited | Administrative & support | 2013 |
| Andy's Pizza Vending Ltd | Wholesale & retail | 2025 |
| Anew Group Limited | Other services | 2021 |
| Anew Health Limited | Health & social care | 2019 |
| Anew Medical Aesthetics Limited | Other services | 2014 |
| Anew Medical Services Limited | Health & social care | 2022 |
| Anew Property Ltd | Real estate | 2022 |
| Anew Training Limited | Education | 2019 |
| Anexhold Limited | Financial services | 2012 |
| Angel Collection Limited | Wholesale & retail | 2022 |
| Angel Eyes Essex Aesthetics and Health Care Ltd | Administrative & support | 2018 |