| Alpha Amateur Boxing Club Limited | Arts & recreation | 2024 |
| Alpha Boxing and Fitness Limited | Arts & recreation | 2024 |
| Alpha Electrical RWB Ltd | Construction | 2026 |
| Alpha Firstcare Ltd | Hospitality | 2020 |
| Alpha Refurbishment and Renovation Ltd | Construction | 2022 |
| Alpha Response UK Limited | Information & communication | 2001 |
| ALPHA38 Limited | Wholesale & retail | 2026 |
| Alpine Bathroom and Kitchen Services Limited | Construction | 2009 |
| Alpinegroup Commercial Ltd | Construction | 2024 |
| Alpineridge Properties Ltd | Real estate | 2024 |
| Alpunch Tooling Limited | Manufacturing | 1988 |
| ALQ Property Ltd | Real estate | 2025 |
| ALS Legal Limited | Professional & scientific | 2017 |
| Alsco Ltd | Wholesale & retail | 2009 |
| Also, There's Ghosts Limited | Arts & recreation | 2024 |
| Alternative Solutions Limited | Manufacturing | 1997 |
| Altisimo Digital Limited | Information & communication | 2018 |
| Altlanco Ltd | Other services | 2018 |
| Altogether Compliant Ltd | Professional & scientific | 2015 |
| Alton Building Preservation Trust | Other services | 1992 |
| Altro-Orbis Limited | Information & communication | 2018 |
| Altyn Solutions Ltd | Information & communication | 2023 |
| ALU Aesthetics Limited | Other services | 2023 |
| ALV Logistics Ltd | Transport & logistics | 2023 |
| ALW Bespoke Limited | Manufacturing | 2014 |
| ALX Group Ltd | Arts & recreation | 2026 |
| AM Carpenters Ltd | Manufacturing | 2024 |
| AM Core Investments Ltd | Real estate | 2026 |
| AM Glovix Ltd | Wholesale & retail | 2025 |
| AMA Project & Design Services Limited | Professional & scientific | 2020 |
| Amaan Safety Limited | Public administration | 2025 |
| Amaanelo Care Services Ltd | Health & social care | 2025 |
| Amadeus 86 Limited | Professional & scientific | 2025 |
| Amaiyah Properties Ltd | Real estate | 2025 |
| Amal Tamras Limited | Health & social care | 2024 |
| Amanda Johnson PR Limited | Administrative & support | 2010 |
| Amara ATI Ltd | Information & communication | 2022 |
| Amaral-Pinto Limited | Real estate | 2024 |
| Amariei Florin Ltd | Transport & logistics | 2018 |
| Amarone Bar and Restaurant Limited | Hospitality | 2023 |
| Amazebowls Limited | Wholesale & retail | 2016 |
| Amazing Care (Swindon) Ltd | Health & social care | 2019 |
| Amazing Summer Properties Ltd | Real estate | 2025 |
| Amber Audio Limited | Arts & recreation | 2000 |
| Amber Court Management (NO 2.) Limited | Households | 1987 |
| Amber Court Management (NO 3) Limited | Households | 1988 |
| Amber Court Management (NO.1) Limited | Households | 1987 |
| Amber Court Management (NO.4) Limited | Households | 1988 |
| Ambermax Consulting Ltd | Information & communication | 2025 |
| Ambicraft Limited | | 1983 |
| Ambros Toys Ltd | Wholesale & retail | 2016 |
| Ambrose House (Swindon) Limited | Real estate | 2012 |
| AMC Finishes Ltd | Construction | 2021 |
| Amco Business Services Limited | Professional & scientific | 2023 |
| Amco Incorporated Limited | Real estate | 2023 |
| Amen Group Properties Limited | Real estate | 2024 |
| American Nails 26 Ltd | Other services | 2023 |
| AMG Cleaning Services Limited | Administrative & support | 2026 |
| AMG Property Rentals Limited | Real estate | 2018 |
| AMI Cleaning Ltd | Administrative & support | 2025 |
| Aminoperformance Ltd | Wholesale & retail | 2023 |
| AML Management Consultancy Limited | Administrative & support | 2010 |
| Ammw Ltd | Professional & scientific | 2025 |
| Amnah Limited | Wholesale & retail | 2021 |
| AMOK88 Holdings Ltd | Other services | 2025 |
| Amorousyy Ltd | Wholesale & retail | 2025 |
| Amour Healthcare Ltd | Public administration | 2023 |
| AMP Computer Consultancy Limited | Information & communication | 2014 |
| Amped Ventures Limited | Financial services | 2020 |
| Ampersand Forward Ltd | Manufacturing | 2025 |
| Ampervolt Analytics Ltd | Professional & scientific | 2026 |
| Ampivolt Ltd | Construction | 2016 |
| Amplecom Limited | Information & communication | 1998 |
| Amplify EV Limited | Energy | 2025 |
| Amplitude Bidco Limited | Financial services | 2025 |
| Amplitude Midco Limited | Financial services | 2025 |
| Amplitude Topco Limited | Financial services | 2025 |
| AMPM247.COM Limited | Construction | 2002 |
| AMR International Development Education Associates Ltd | Professional & scientific | 2025 |
| AMS 1024 Limited | Professional & scientific | 2000 |
| AMS 1052 Limited | Professional & scientific | 2000 |
| AMS 1069 Limited | Information & communication | 2000 |
| AMS 1072 Limited | Information & communication | 2000 |
| AMS 1293 Limited | Professional & scientific | 2002 |
| AMS 1300 Limited | Information & communication | 2002 |
| AMS 1494 Limited | Professional & scientific | 2003 |
| AMS 1508 Limited | Health & social care | 2003 |
| AMS 1520 Limited | Information & communication | 2003 |
| AMS 1846 Limited | Information & communication | 2004 |
| AMS 1857 Limited | Information & communication | 2004 |
| AMS 1861 Limited | Professional & scientific | 2004 |
| AMS Accountancy Group Limited | Professional & scientific | 2001 |
| AMS Accountancy Ltd | Professional & scientific | 2000 |
| AMS Nominees Limited | Administrative & support | 1997 |
| Amsim Properties Ltd | Real estate | 2022 |
| Amtec Corporation Limited | Information & communication | 2009 |
| Amuco (Ilminster) Limited | Administrative & support | 2009 |
| AMX Projects Ltd | Information & communication | 2010 |
| Amzon Limited | Health & social care | 2015 |
| Amzu 2010 Ltd | Professional & scientific | 2025 |