| Aprs Services Limited | Professional & scientific | 2017 |
| Apruvo Ltd | Information & communication | 2026 |
| Apso Ltd | Real estate | 2024 |
| Apus Bidco Limited | Information & communication | 2021 |
| APW Holdings Limited | Professional & scientific | 2009 |
| APX Physique Limited | Education | 2022 |
| APX Treatments Limited | Arts & recreation | 2017 |
| AQE Limited | Professional & scientific | 2026 |
| Aqua Rosa Limited | Professional & scientific | 2006 |
| Aquafix Plumbing Limited | Construction | 2015 |
| Aqualine Services Limited | Construction | 2017 |
| Aquarium Software Ltd | Information & communication | 2006 |
| Aquateal Solutions Limited | Professional & scientific | 2024 |
| Aquila Civil Engineering Services Limited | Administrative & support | 2014 |
| Aquila Golf Ltd | Professional & scientific | 2022 |
| Aquilaheywood Limited | Information & communication | 2005 |
| AR Clinical Services Ltd | Health & social care | 2026 |
| AR Qureshi Ltd | Health & social care | 2022 |
| Arafa Care Limited | Health & social care | 2024 |
| Araglen Properties Limited | Real estate | 1986 |
| Aramazd Developments Limited | Construction | 2025 |
| Aras Property Solutions Ltd | Real estate | 2024 |
| Arbenigol Consultancy Limited | Administrative & support | 2016 |
| ARC Design Projects Limited | Construction | 2021 |
| ARC Design Services Limited | Professional & scientific | 2004 |
| ARC Stage Hire Limited | Other services | 2018 |
| Arcadia Efuels UK Limited | Wholesale & retail | 2022 |
| Arch Eleven Ltd | Manufacturing | 2025 |
| Archada Ltd | Real estate | 2026 |
| Archangel Beats Limited | Extraterritorial | 2014 |
| Archhaven Estates Limited | Real estate | 2001 |
| Archhaven Properties Ltd | Real estate | 2025 |
| Archikei Ltd | Professional & scientific | 2022 |
| Architecture Advance Limited | Information & communication | 2024 |
| Archive House Agency Ltd | Professional & scientific | 2024 |
| Archived Ltd | Professional & scientific | 2025 |
| Archna’S Medical and IT Services Limited | Information & communication | 2020 |
| Archway Assistance Limited | Financial services | 2025 |
| Arctic Homes Limited | Real estate | 2008 |
| Arcus 101 Limited | Financial services | 2023 |
| Ardan Advisory Limited | Professional & scientific | 2026 |
| Ardent Automation Limited | Information & communication | 2018 |
| Ardis X Limited | Professional & scientific | 2022 |
| Ardreigh Consulting Limited | Professional & scientific | 2024 |
| Arena Sponsorship Limited | Other services | 2014 |
| Aresas Limited | Administrative & support | 2015 |
| Arfys Curry & Kebabs Ltd | Hospitality | 2026 |
| ARH Investments Limited | Real estate | 1957 |
| ARI Accounting Services Limited | Professional & scientific | 2021 |
| Ariair Travel Ltd | Administrative & support | 2020 |
| Arian Construction Limited | Construction | 2025 |
| Arian EMS Group Finance Limited | Financial services | 2025 |
| Arian EMS Group Holdings Limited | Financial services | 2025 |
| Arielle's Care Ltd | Health & social care | 2020 |
| Arielles Homes Ltd | Health & social care | 2019 |
| Ariftech Limited | Professional & scientific | 2024 |
| Arimaz Limited | Professional & scientific | 2023 |
| Arin Limited | Hospitality | 2016 |
| Arise Estates Limited | Real estate | 2013 |
| Arivi Engineering Ltd | Information & communication | 2025 |
| Ariyaan Properties Ltd | Real estate | 2021 |
| Arkadia Questionnaires Ltd | Professional & scientific | 2005 |
| Arkena Ltd | Wholesale & retail | 2026 |
| Arley House Estates Limited | Other services | 2025 |
| Arley House Ltd | Wholesale & retail | 2001 |
| Armaan Legals Limited | Health & social care | 2017 |
| Armadillo Limited | Other services | 1970 |
| Armand International Limited | Arts & recreation | 2000 |
| Armclaim Limited | Wholesale & retail | 1989 |
| Armco Investments Limited | Real estate | 2023 |
| Armedal Ltd. | Construction | 2017 |
| Armour Jewellery Limited | Manufacturing | 2025 |
| Armstrong Prosthetics and Orthotics Ltd | Health & social care | 2023 |
| Armstrong Strategic Advisory Limited | Professional & scientific | 2026 |
| Arnolds Yard Management Company Limited | Real estate | 2000 |
| Around the Clock FUN Ltd | Health & social care | 2024 |
| ARP Controls Ltd | Professional & scientific | 2023 |
| Arp-Uk Limited | Information & communication | 2021 |
| Arpita Property Management Limited | Real estate | 2018 |
| Arqmed Ltd | Wholesale & retail | 2025 |
| Arrisan Ltd | Other services | 2022 |
| Arrow Film Distributors Limited | Information & communication | 1991 |
| Arrowhere Equipment Limited | Professional & scientific | 2014 |
| Art With Smiles CIC | Health & social care | 2022 |
| Artbio Limited | Professional & scientific | 2023 |
| Artefact Fine Furnishings Limited | Manufacturing | 2013 |
| Artel Technologies Ltd | Information & communication | 2014 |
| Artemis Europe Ltd | Real estate | 2020 |
| Arterix Limited | Health & social care | 2026 |
| Artesium Associates Limited | Professional & scientific | 2003 |
| Arteus Digital Media Limited | Information & communication | 2014 |
| Artha Balance Limited | Professional & scientific | 2024 |
| Arthaum Group Limited | Real estate | 2022 |
| Arthur Industries Ltd | Real estate | 2020 |
| Article 8 Limited | Professional & scientific | 2023 |
| Artifex Natura Ltd | Wholesale & retail | 2022 |
| Artificial Grass Products Ltd | Wholesale & retail | 2015 |
| Artihcus Solutions Limited | Professional & scientific | 2025 |
| Artocus Group Ltd | Other services | 2020 |
| Artzu Limited | Wholesale & retail | 2003 |