| Alpha Manufacturing Hixon Limited | Manufacturing | 1994 |
| Alpha WCS Limited | Administrative & support | 2021 |
| Alrog Investments Ltd | Professional & scientific | 2019 |
| Alsaarem Co., Ltd | Wholesale & retail | 2025 |
| Altara Global Limited | Professional & scientific | 2025 |
| Altecnic Limited | Wholesale & retail | 1987 |
| Altezza People UK Limited | Professional & scientific | 2021 |
| Althea Wellness & Aesthetics Ltd | Other services | 2005 |
| Altinordu Limited | Hospitality | 2024 |
| Aluminium Frames and Tooling Solutions Ltd | Manufacturing | 2016 |
| Alvestoke Finance Limited | Financial services | 2013 |
| Alwafaa Company Limited | Wholesale & retail | 2025 |
| AM Moran Holdings Limited | Financial services | 2009 |
| AM Professional Services Ltd | Professional & scientific | 2025 |
| AMA Agriculture Limited | Agriculture & fishing | 2023 |
| Amarlot Properties Ltd | Real estate | 2021 |
| Amaze Care Ltd | Health & social care | 2024 |
| Ambec Group Ltd | Financial services | 2023 |
| Ambrosia Supply Source Limited | Transport & logistics | 2024 |
| Ambucare Ltd | Wholesale & retail | 2015 |
| AMC (Cars) Ltd | Wholesale & retail | 2020 |
| AMC Medicare UK Ltd | Wholesale & retail | 2020 |
| Amcars 888 Limited | Wholesale & retail | 2021 |
| Amerton Engineering Limited | Professional & scientific | 2019 |
| Amerton Farm Limited | Arts & recreation | 2016 |
| AMG Healthcare Consultancy Ltd | Professional & scientific | 2023 |
| AMG Lighting Ltd | Extraterritorial | 2011 |
| Amicis Group Limited | Information & communication | 2021 |
| Amicis Holdings Limited | Information & communication | 2020 |
| AMK Drive Ltd | Transport & logistics | 2014 |
| AMM Innovations Ltd | Extraterritorial | 2022 |
| AMM Support Ltd | Professional & scientific | 2011 |
| Amoto Wheels | Extraterritorial | 2020 |
| AMP Training Ltd | Education | 2023 |
| AMR Haulage Ltd | Transport & logistics | 2026 |
| Anaya &Co Ltd | Health & social care | 2021 |
| ANB Mining Ltd. | Professional & scientific | 2014 |
| Anchor Care Support Limited | Health & social care | 2025 |
| Anchorhold Camping Ltd. | Professional & scientific | 2009 |
| Anderson Dixon Properties Limited | Financial services | 2016 |
| Anderson-Dixon Limited | Financial services | 2014 |
| Andrew a Wilson Limited | Arts & recreation | 2024 |
| Andrew Halden & Associates Ltd | Real estate | 2021 |
| Andrew Lawson Visuals Ltd | Professional & scientific | 2003 |
| Andrew Wilson Associate Limited | Health & social care | 2016 |
| Angel Beauty and Brow Bar Ltd | Other services | 2024 |
| Anglia (China) Limited | Manufacturing | 2021 |
| Anglo Cathay Development Limited | Real estate | 2015 |
| Anglo Western Ltd | Manufacturing | 2017 |
| Anhui Huaxing Chemical Industry Co., Ltd | Manufacturing | 2024 |
| Anik Appaji Limited | Health & social care | 2021 |
| Animal Manor Limited | Wholesale & retail | 2025 |
| Animals R US Ltd | Hospitality | 2025 |
| Anjiaying International Trading Co., Ltd | Wholesale & retail | 2014 |
| Anlan London Limited | Manufacturing | 2021 |
| Anneliese Delaunay Prints & Design Ltd | Wholesale & retail | 2021 |
| Annie's GAS Services Ltd. | Construction | 2020 |
| Annlu Ltd | Wholesale & retail | 2023 |
| Annsar Ltd | Professional & scientific | 2012 |
| Anok Precision UK Ltd | Manufacturing | 2024 |
| Ansaad Limited | Information & communication | 2021 |
| Ansell Safety Limited | Construction | 2025 |
| Anthony Carden Holdings Limited | Professional & scientific | 2015 |
| Anthony John Wilmott Holdings Limited | Financial services | 2020 |
| Anunnaki Research Ltd. | Information & communication | 2022 |
| Anvil Fabrications (Stafford) Limited | Manufacturing | 2008 |
| Anyzanod Limited | Wholesale & retail | 2025 |
| AOA Birmingham Homes Ltd | Real estate | 2024 |
| Aobo Financial Group Ltd | Wholesale & retail | 2025 |
| Aopeng Ltd | Wholesale & retail | 2025 |
| AP Taylor Properties (Holdings) Limited | Hospitality | 2025 |
| Apan Trans Ltd | Transport & logistics | 2023 |
| APC Accountancy (Staffs) Ltd | Professional & scientific | 2011 |
| APC Enterprises (Midlands) Ltd | Financial services | 2018 |
| APC Project Management Services Limited | Construction | 2025 |
| Aperitif UK Ltd | Hospitality | 2021 |
| Apeton Property & Development Limited | Construction | 2023 |
| Apex Aviation Limited | Transport & logistics | 2025 |
| Apex Management Systems Ltd | Professional & scientific | 2026 |
| Apex TK Limited | Manufacturing | 2025 |
| Apex UK Sales Limited | Manufacturing | 2003 |
| APF19 Insight Limited | Professional & scientific | 2023 |
| Apgtec Limited | Administrative & support | 2016 |
| APK Property Ltd | Real estate | 2019 |
| Apollo Transport Ltd | Transport & logistics | 2021 |
| App Haus Limited | Information & communication | 2010 |
| Apsd Properties Limited | Hospitality | 2025 |
| APT Industry and Trade Co., Ltd | Wholesale & retail | 2023 |
| Aqua Industrial Coatings Limited | Construction | 2007 |
| Aqua-Tunnel Ltd | Manufacturing | 2025 |
| Aquagem Heating Limited | Administrative & support | 2009 |
| Aquagem Holdings Ltd | Financial services | 2022 |
| Aquaglobe Ltd | Administrative & support | 2025 |
| Aquarius Property Ltd | Real estate | 2025 |
| AR Holdings 24 Limited | Financial services | 2023 |
| AR Lead Specialist Limited | Construction | 2017 |
| AR Plumbing & GAS Services Ltd | Construction | 2013 |
| Aracya Limited | Manufacturing | 2024 |
| Aral Engineering Services Ltd | Professional & scientific | 2012 |
| Aramax Management Solutions Limited | Professional & scientific | 1999 |