| Appoint Staff Limited | Professional & scientific | 1996 |
| Apposite Limited | Information & communication | 2021 |
| Appreciate Property Stays Ltd | Real estate | 2026 |
| Approach Practice Limited | Health & social care | 2007 |
| Approved Roof Care Limited | Construction | 2024 |
| Apra Care Ltd | Health & social care | 2023 |
| Apricitea Ltd | Real estate | 2022 |
| APS Catering Kent Ltd | Hospitality | 2025 |
| Apsc Digital Ltd | Information & communication | 2025 |
| Apsc Holdings Ltd | Financial services | 2025 |
| Apsley Mechanical Services Ltd | Other services | 2016 |
| Apsley Properties Limited | Real estate | 2019 |
| APT Air Conditioning Limited | Construction | 2026 |
| APV Support Ltd | Transport & logistics | 2024 |
| Aqua Technics Pools UK Limited | Extraterritorial | 2025 |
| Aquafuel Renewables Limited | Professional & scientific | 2008 |
| Aquafuel Research Limited | Professional & scientific | 2001 |
| Aquafuel Tallow Technologies Limited | Professional & scientific | 2011 |
| Aquarius Tech Services Ltd | Information & communication | 2015 |
| Aquatic Emporium Ltd | Wholesale & retail | 2019 |
| Aquila Management Solutions Ltd | Professional & scientific | 2020 |
| Aquilanta Limited | Professional & scientific | 2018 |
| Aquitaine Estates Ltd | Construction | 2012 |
| Aquium Limited | Professional & scientific | 2017 |
| AR Lettings (UK) Limited | Real estate | 2019 |
| Arain Bros Limited | Wholesale & retail | 2024 |
| Aramsofi Ltd | Other services | 2025 |
| Aras Estates Limited | Real estate | 2018 |
| Arbor & Stone Ltd | Administrative & support | 2025 |
| ARC Cafe Limited | Hospitality | 2016 |
| ARC Coachworks Limited | Wholesale & retail | 2010 |
| ARC Glazing Limited | Construction | 2022 |
| ARC One Group Limited | Construction | 2015 |
| Arcanist Limited | Wholesale & retail | 2019 |
| Arceon Ltd | Manufacturing | 2026 |
| Arch Beauty Ltd | Other services | 2020 |
| Arch Konsult Ltd | Financial services | 2017 |
| Archer Power System Services Ltd | Professional & scientific | 2011 |
| Archer RFD Limited | Professional & scientific | 2022 |
| Architectural Design LAB Ltd. | Professional & scientific | 2014 |
| ARCHITECTURE2INTERIOR Design Ltd | Professional & scientific | 2022 |
| Archridge Limited | Information & communication | 2012 |
| Archway Project Management Limited | Professional & scientific | 2019 |
| Arco Training Services Limited | Administrative & support | 2002 |
| Arcway Construction Ltd | Construction | 2007 |
| ARD Pipe Design Ltd | Professional & scientific | 2024 |
| Ardmore 66 Ltd | Health & social care | 2025 |
| Ardmore Woodley Limited | Other services | 2020 |
| Ardovries UK Limited | Extraterritorial | 1991 |
| Ardsbeg Developments Limited | Real estate | 2015 |
| Ardua Communication Limited | Other services | 1993 |
| Area D Sport Limited | Wholesale & retail | 2025 |
| Arena Health Ltd | Manufacturing | 2019 |
| ARG Designer Kitchen & Bedrooms Ltd | Construction | 2021 |
| Argos Construction and Development Ltd | Health & social care | 2024 |
| ARI Travel Limited | Transport & logistics | 2025 |
| Aria Assets Ltd | Real estate | 2021 |
| Aria Driving School Ltd | Education | 2020 |
| Aria Motors Ltd | Wholesale & retail | 2024 |
| Ariel Logistics Ltd | Transport & logistics | 2026 |
| Ariftuli Ltd | Hospitality | 2017 |
| Arigen Biotechnology Ltd | Manufacturing | 2006 |
| Aris Cafe Ltd | Hospitality | 2024 |
| Aristocars (Kent) Ltd | Transport & logistics | 2023 |
| Ariwaa Ltd | Wholesale & retail | 2025 |
| ARJ Landscape and Groundworks Limited | Construction | 2019 |
| Arjj Investment Ltd | Real estate | 2023 |
| Arjp Ltd | Wholesale & retail | 2024 |
| ARK Animal Encounters Ltd | Education | 2025 |
| ARK Creative Limited | Information & communication | 2003 |
| ARK Garden & Property Services Ltd | Administrative & support | 2012 |
| Arkan (Kent) Holdings Ltd | Manufacturing | 2025 |
| Arkay Holdings Limited | Financial services | 2019 |
| Arkham Investments Limited | Real estate | 2022 |
| Arkitekton Dover Ltd | Real estate | 2020 |
| Arkitekton Ltd | Other services | 2019 |
| Arkitekton Nunnery Fields Ltd | Real estate | 2021 |
| Arkitekton Properties Ltd | Real estate | 2020 |
| Arkitekton ST Leonards 1 Ltd | Real estate | 2025 |
| Arkitekton ST Leonards Ltd | Real estate | 2020 |
| Arlberg Developments Limited | Real estate | 2014 |
| Armac Limited | Construction | 2025 |
| Armada Homes Limited | Construction | 1999 |
| Armary LLP | | 2025 |
| Armed Forces Financial Services Limited | Extraterritorial | 2013 |
| Armstrong Music Ltd | Manufacturing | 2022 |
| Armufa Entertainment Limited | Arts & recreation | 2024 |
| Arnold & Court Ltd | Construction | 2006 |
| Arnold and Hobbs Limited | Other services | 2015 |
| Arocor Limited | Administrative & support | 2011 |
| Aroma of WYE Ltd | Hospitality | 2024 |
| Aron Building Ltd | Construction | 2017 |
| Aroraspractice Ltd | Professional & scientific | 2013 |
| Arran Pharmaceuticals Ltd | Public administration | 2025 |
| Arrow Communications Limited | Extraterritorial | 2015 |
| Arrow Converged Solutions Limited | Information & communication | 2015 |
| Arrows Darts Centre Limited | Extraterritorial | 2010 |
| Arsh Exchange Ltd | Wholesale & retail | 2025 |
| Art Advisory & Investment Ltd | Other services | 2022 |
| Art Building Maintenance Ltd | Construction | 2023 |