| Anytime Recycling Ltd | Water & waste | 2017 |
| Anzalna Ltd | Wholesale & retail | 2026 |
| Apeiron Windows and Doors Ltd | Construction | 2022 |
| Apex Engineering & Training Ltd | Professional & scientific | 2025 |
| Apex Investment Holdings Limited | Real estate | 2024 |
| Apex Mount Limited | Real estate | 2025 |
| Apex Plan & Build Ltd | Construction | 2017 |
| Apiavi Property Limited | Real estate | 2024 |
| Apni Roti Catering Ltd | Hospitality | 2024 |
| Apollo Core Investments Ltd | Financial services | 2026 |
| Apollo Health & Education Ltd | Health & social care | 2023 |
| Appe Trading Ltd | Wholesale & retail | 2026 |
| Appfa Ltd | Real estate | 2016 |
| Apple Management Limited | Real estate | 2021 |
| Apricot Holdings Limited | Real estate | 2015 |
| Aprillis Limited | Real estate | 2018 |
| Aqua Farming Limited | Wholesale & retail | 2025 |
| Aqua Fresh Fish Limited | Agriculture & fishing | 2022 |
| Aquagrove Limited | Wholesale & retail | 2025 |
| Aquality Trading & Consulting Limited | Construction | 2004 |
| Aquarius Accessories (London) Ltd | Wholesale & retail | 2019 |
| AR Elite Accounting Solutions Ltd | Professional & scientific | 2022 |
| Arabian Luxury Services Ltd | Administrative & support | 2017 |
| ARB Consulting Limited | Other services | 2024 |
| ARC Web Limited | Information & communication | 2000 |
| Archangel Creative Limited | Professional & scientific | 2015 |
| Ardit (UK) Ltd | Construction | 2013 |
| ARE Hama Limited | Transport & logistics | 2019 |
| Argan of Eden Ltd | Manufacturing | 2020 |
| Arhaz Cosmetics Limited | Wholesale & retail | 2024 |
| Ariana Autos Ltd | Wholesale & retail | 2016 |
| ARJ Management Group Ltd | Health & social care | 2023 |
| ARK Stationery Limited | Wholesale & retail | 2004 |
| Arka Investments Limited | Real estate | 2016 |
| Arko Shop Limited | Wholesale & retail | 2003 |
| Armbuild Construction Limited | Construction | 2022 |
| Armin Plus Limited | Wholesale & retail | 2023 |
| Arora Auto & Logistics Ltd | Wholesale & retail | 2025 |
| Arosa UK Limited | Transport & logistics | 2016 |
| Arpan Patel's Co. Ltd | Wholesale & retail | 2026 |
| Arqalina Limited | Hospitality | 2018 |
| Arrived Limited | Transport & logistics | 1994 |
| Art Connect Electrical Ltd | Construction | 2025 |
| Art of Service Ltd | Other services | 2014 |
| Artdan Construction Limited | Construction | 2017 |
| Artgian Ltd | Construction | 2024 |
| Artha Business Hub Ltd | Wholesale & retail | 2026 |
| Artical Heights Ltd | Information & communication | 2017 |
| Artisan Kitchens London Limited | Wholesale & retail | 2017 |
| Artisan Properties London Limited | Real estate | 2020 |
| Artison Skills Limited | Construction | 2024 |
| Artist Brighton Limited | Other services | 2013 |
| Artist Horsham Limited | Other services | 2023 |
| Aruna Fashion House Ltd | Wholesale & retail | 2021 |
| Arusha Holdings Ltd | Hospitality | 2024 |
| Arya Cars Ltd | Transport & logistics | 2015 |
| Aryadanchi Healthcare Ltd | Health & social care | 2023 |
| AS Greenford Heating and Plumbing (UK) Ltd | Wholesale & retail | 2015 |
| ASA Scaffolding Ltd | Construction | 2025 |
| Asat Business Solutions Limited | Professional & scientific | 2024 |
| ASE Hope Ltd | Health & social care | 2022 |
| Asea Ltd | Professional & scientific | 2010 |
| Asgard Stones Ltd | Wholesale & retail | 2020 |
| Ashdeenu Management Limited | Real estate | 2021 |
| Ashdown Whitlock Limited | Professional & scientific | 2025 |
| Ashish Khanna Ltd | Health & social care | 2012 |
| Ashlee Films Inc Ltd | Information & communication | 2010 |
| Ashton Rowe Ltd | Other services | 2015 |
| ASI Transfers Ltd | Transport & logistics | 2025 |
| ASK Digital Limited | Information & communication | 2016 |
| ASK News Group Ltd | Information & communication | 2026 |
| Asmaan TV Ltd | Manufacturing | 2021 |
| Asmr Builders Ltd | Construction | 2021 |
| ASO Construction Ltd | Construction | 2022 |
| Aspire & Blume SSA Limited | Real estate | 2022 |
| Aspire Roofing & Construction Services. Ltd | Construction | 2025 |
| ASR Invest Limited | Real estate | 2017 |
| Assured Plus Limited | Real estate | 2010 |
| Astha Court (Greenford) Management Company Ltd | Real estate | 2013 |
| Aston Giles & Co Ltd | Wholesale & retail | 2018 |
| Astor Lodge Holdings Limited | Real estate | 1962 |
| Astrava Solutions Ltd. | Information & communication | 2017 |
| Astrid & Murcott Ltd | Wholesale & retail | 2025 |
| Asulkowski Ltd | Manufacturing | 2014 |
| ASV Management Ltd | Information & communication | 2025 |
| Async Investments Ltd | Real estate | 2017 |
| At&T Construction Limited | Construction | 2015 |
| ATC Trading INT Ltd | Wholesale & retail | 2019 |
| Ateambuilding Ltd | Construction | 2019 |
| Atelier Travel Ltd | Administrative & support | 2021 |
| Atfitnessuk Ltd | Other services | 2021 |
| Athlito Sports Ltd | Wholesale & retail | 2026 |
| Atlantic Bar (Buncrana) Limited | Wholesale & retail | 2013 |
| Atlas Exporters Ltd | Wholesale & retail | 2025 |
| Atlee Crispin Mitchell Limited | Extraterritorial | 2024 |
| Atmex Limited | Construction | 2003 |
| Atmos Fidgets Ltd | Wholesale & retail | 2024 |
| Atravelsyearly Ltd | Professional & scientific | 2024 |
| Attasiaa Media Ltd | Information & communication | 2024 |
| Attunement Consultancy Limited | Professional & scientific | 2017 |