| Allen Building Limited | Construction | 2018 |
| Alliance Media Group (JAS) Ltd | Administrative & support | 2018 |
| Allied Aerosystems Limited | Manufacturing | 1997 |
| Allied Aerosystems Trustees Limited | Financial services | 2004 |
| Allstar Designs Ltd | Administrative & support | 2019 |
| ALM Agriculture Limited | Agriculture & fishing | 2025 |
| Alma Gira Limited | Wholesale & retail | 2024 |
| Alpha External Render Systems Limited | Construction | 2014 |
| Alpha Travels RCT Ltd | Transport & logistics | 2024 |
| Alphabet Group Limited | Wholesale & retail | 2018 |
| Alpine Motorbike Tours Ltd | Administrative & support | 2025 |
| Altitude Ropes Access Ltd | Construction | 2025 |
| Altiuss Limited | Information & communication | 2026 |
| Altura Chiropractic Ltd | Health & social care | 2011 |
| Altura Industrial Development Limited | Professional & scientific | 2015 |
| Alumate Limited | Manufacturing | 2015 |
| Alwayz Clean Power International Limited | Professional & scientific | 2016 |
| Alyn Wallace Photography Limited | Professional & scientific | 2022 |
| Amanto International Trade Limited | Wholesale & retail | 2021 |
| AMC Telecoms Limited | Information & communication | 2011 |
| AMD Rocket Services Limited | Professional & scientific | 2023 |
| Americancarweddings Limited | Transport & logistics | 2017 |
| Amethyst Precision Engineering Ltd | Professional & scientific | 2025 |
| Amlaen Ltd | Other services | 2009 |
| Ampm Associates LLP | | 2012 |
| Amtl Property Limited | Real estate | 2020 |
| AND Collectibles Ltd | Wholesale & retail | 2023 |
| Anderson Stanley Services Ltd | Financial services | 2016 |
| Andrews Property Services UK Limited | Professional & scientific | 2015 |
| Andrews Sofa Deliveries Limited | Transport & logistics | 2026 |
| Angel Woodcraft Limited | Manufacturing | 2013 |
| Anglicolor Cosmetic Co., Ltd | Extraterritorial | 2021 |
| Anne Invest Co., Limited | Extraterritorial | 2009 |
| Annest Ltd | Real estate | 2025 |
| Anstee Group Ltd | Wholesale & retail | 2024 |
| Anyu Electrical & Mechanical Equipment (UK) Co., Ltd | Wholesale & retail | 2014 |
| Anzani Republic Ltd | Arts & recreation | 2019 |
| Apex Academy CDF Ltd | Education | 2026 |
| Apex Business Consultants Ltd | Public administration | 2023 |
| APS Commercial Ltd | Transport & logistics | 2011 |
| Aqua Heat Solutions (Wales) Limited | Construction | 2022 |
| Aqua Heating and Plumbing Ltd | Construction | 2023 |
| ARC Academy Holdings UK Limited | Financial services | 2017 |
| ARC Labour Solutions Ltd | Other services | 2017 |
| ARC Medicals Ltd | Health & social care | 2016 |
| ARC Plant and Civils Ltd | Administrative & support | 2017 |
| Archaeological Services Wales Limited | Administrative & support | 2013 |
| Archaeology England Limited | Administrative & support | 2013 |
| Archer Consultancy Ltd | Professional & scientific | 2020 |
| Arctic Spire Ltd | Information & communication | 2018 |
| Arcticoak Limited | Real estate | 2016 |
| Ardistel Limited | Wholesale & retail | 2025 |
| Arius London Ltd | Wholesale & retail | 2026 |
| Around the Bend Driving School South Wales Ltd | Education | 2024 |
| Art in the Attic Co-Operative CIC | Wholesale & retail | 2020 |
| Artis Community/Cymuned Limited | Arts & recreation | 2012 |
| Asariparambil Ltd | Transport & logistics | 2026 |
| ASF Foods Ltd | Hospitality | 2025 |
| Ashfield Construction Services Ltd | Manufacturing | 2023 |
| Ashgrove Healthcare Ltd | Health & social care | 2018 |
| Ashley Baker Hopkins Limited | Real estate | 2025 |
| Ashley Bale IT Services Ltd | Information & communication | 2021 |
| Ashley HR Consultancy Limited | Administrative & support | 2015 |
| Ashtoncarter Property Developments Ltd | Construction | 2019 |
| ASL Consultants Limited | Professional & scientific | 2012 |
| Aspire Construction & Groundworks Ltd | Construction | 2026 |
| Assam Industrial Ltd | Wholesale & retail | 2021 |
| Astud CYF | Information & communication | 2018 |
| Atega Ltd | Professional & scientific | 2015 |
| Ategi Limited | Health & social care | 1994 |
| Atherton Distribution Ltd | Transport & logistics | 2018 |
| Atherton Health Ltd | Wholesale & retail | 2026 |
| Atlantic Door Maintenance Ltd | Other services | 2011 |
| ATM Food Ltd | Hospitality | 2023 |
| ATS Headwear & Accessories Ltd | Manufacturing | 2026 |
| Aurovia Trade Ltd | Wholesale & retail | 2025 |
| Austin & Morgan Properties Ltd | Real estate | 2019 |
| Austin Motor Company 2015 Ltd | Wholesale & retail | 2017 |
| Auto Moto Tyre & Exhaust Limited | Wholesale & retail | 2007 |
| Auto Range Trade Centre Ltd | Wholesale & retail | 2020 |
| Automation Excellence Limited | Administrative & support | 2009 |
| Automotive Movements UK Limited | Transport & logistics | 2016 |
| Autoparts Car Ltd | Wholesale & retail | 2023 |
| Autotop UK Co., Limited | Wholesale & retail | 2025 |
| Avant Guard Developments Ltd | Construction | 2017 |
| Aviation Jewellery Ltd | Manufacturing | 2025 |
| AW Drylining Ltd | Construction | 2022 |
| AW Ponty Ltd | Wholesale & retail | 2023 |
| Awae Limited | Administrative & support | 2010 |
| Awix Media Ltd | Information & communication | 2026 |
| Aydin Haulage Ltd | Transport & logistics | 2019 |
| Azzweld Limited | Construction | 2021 |
| B W M Limited | Manufacturing | 1996 |
| B&C Play Clubs Limited | Health & social care | 2021 |
| B. Speck & Sons Limited | Construction | 1994 |
| B1 Roofing Ltd | Construction | 2024 |
| B2 Event Crew Ltd | Arts & recreation | 2023 |
| Babanod Ltd | Information & communication | 2019 |
| Baby Bandito Limited | Arts & recreation | 2021 |
| Bacmurrya Ltd | Wholesale & retail | 2017 |