| Archpree Properties Ltd | Real estate | 2025 |
| Archway Bricklaying Contractors Limited | Construction | 2013 |
| Arctic FOX Property Ltd | Real estate | 2024 |
| Arcurban Ltd | Construction | 2016 |
| Ardale Residential UK Limited | Real estate | 2026 |
| Ardassie Media Ltd | Professional & scientific | 2023 |
| Arden Tigress Limited | Real estate | 2019 |
| Ardentworldconferences Limited | Administrative & support | 2019 |
| Ardor Padel Ltd | Arts & recreation | 2026 |
| Areeb Realty Ltd | Real estate | 2026 |
| Areed-Moeed-Inara Ltd | Real estate | 2026 |
| Arer Investments | Financial services | 2025 |
| Ares Supply Ltd | Wholesale & retail | 2024 |
| Arevna Insourcing Ltd | Health & social care | 2020 |
| Arevna Limited | Wholesale & retail | 2018 |
| Arevna Partners Ltd | Professional & scientific | 2020 |
| Arfon Healthcare Solutions Limited | Administrative & support | 2024 |
| Argent Wealth Management Limited | Financial services | 2010 |
| Arglass Ltd | Construction | 2021 |
| Argoan Ventures Ltd | Construction | 2025 |
| Argonaut Training Facilities Limited | Education | 2007 |
| Argyll-Brent Contracts Ltd | Extraterritorial | 2006 |
| Arhm Consulting Limited | Professional & scientific | 2026 |
| Arhm Management Limited | Professional & scientific | 2022 |
| Aria Pizza Ltd | Hospitality | 2024 |
| Arianne Property Compliance Solutions Ltd | Real estate | 2024 |
| Arista Electronic Systems Ltd | Manufacturing | 2018 |
| Arista Product Development Ltd | Professional & scientific | 2020 |
| ARJ Spraying Limited | Construction | 2023 |
| ARK Tech Autos Ltd | Wholesale & retail | 2019 |
| ARK3162 Ltd | Wholesale & retail | 2026 |
| Arkenrock Ltd | Information & communication | 2023 |
| Arkray Factory Ltd. | Manufacturing | 1985 |
| Arkray Limited | Wholesale & retail | 2008 |
| Arks Jogia Ltd | Financial services | 2025 |
| Arlake Ltd | Real estate | 2025 |
| Arlo's Construction Ltd | Construction | 2026 |
| Armadillo Contractors Ltd | Construction | 2024 |
| Arman Alam Chambers Limited | Professional & scientific | 2020 |
| Armani Services (HW) Ltd | Construction | 2023 |
| ARN Advisory Services Ltd | Professional & scientific | 2025 |
| Arna Solutions Ltd | Construction | 2016 |
| Arna Trade Ltd | Wholesale & retail | 2017 |
| Arnison Capital Ltd | Real estate | 2025 |
| Arnna Studios Ltd | Arts & recreation | 2025 |
| Arose Consulting Ltd | Professional & scientific | 2024 |
| Arose World Ltd | Wholesale & retail | 2025 |
| Arou Ltd | Information & communication | 2024 |
| Aroura Glamping Co Ltd | Administrative & support | 2025 |
| ARP Electrical Ltd | Construction | 2016 |
| Arrow Partnership Limited | Real estate | 2006 |
| Arrow Planning Limited | Administrative & support | 2017 |
| Arrow Transport (H/W) Limited | Transport & logistics | 2016 |
| ARS Financial Consulting Limited | Professional & scientific | 2012 |
| Arslan Hanif Ltd | Wholesale & retail | 2025 |
| Art 13 Ltd | Construction | 2013 |
| Art Homes Ltd | Construction | 2023 |
| Art of Learning INT Ltd | Education | 2011 |
| Artefact Cards Limited | Wholesale & retail | 2013 |
| Artemis Acru Ltd | Wholesale & retail | 2025 |
| Artio Green Ltd | Professional & scientific | 2024 |
| Artur and SON Stove and Flue System Ltd | Construction | 2023 |
| Arundel 1960 Limited | Extraterritorial | 2013 |
| Arundel Film Limited | Information & communication | 2025 |
| Arunodaya Properties Ltd | Real estate | 2021 |
| ARY Plumbing and Heating Ltd | Construction | 2024 |
| Aryaan Consulting Limited | Information & communication | 2014 |
| Aryas (London) Ltd | Wholesale & retail | 2019 |
| AS Auto Service Limited | Wholesale & retail | 2025 |
| AS Companies Ltd | Wholesale & retail | 2018 |
| AS Contrax Ltd | Construction | 2025 |
| AS Electronics Ltd | Construction | 2017 |
| AS Elite Ltd | Professional & scientific | 2026 |
| AS Eyecare Ltd | Health & social care | 2025 |
| AS Eyes Ltd | Wholesale & retail | 2023 |
| AS Guardians Limited | Education | 2022 |
| AS Holdco Limited | Financial services | 2023 |
| AS Midco Limited | Financial services | 2023 |
| AS Opco Limited | Financial services | 2023 |
| AS Southern Limited | Administrative & support | 2016 |
| ASA Global Solutions Ltd | Administrative & support | 2025 |
| ASA Linen Ltd | Other services | 2025 |
| Asaf a Limited | Other services | 2023 |
| Asare Simms Limited | Information & communication | 2014 |
| Asba Ltd | Real estate | 2025 |
| ASC Digital Limited | Information & communication | 2025 |
| ASC247 Limited | Administrative & support | 2022 |
| Ascend Service Management Limited | Information & communication | 2025 |
| Ascenda Collective Limited | Wholesale & retail | 2025 |
| Asdma Ltd | Other services | 2019 |
| Aseptic Limited | Manufacturing | 2020 |
| Asgard Arts Ltd | Administrative & support | 2010 |
| ASH & Maple Limited | Manufacturing | 2015 |
| ASH Dream Property Ltd | Real estate | 2025 |
| ASH Gadhvi Ltd | Information & communication | 2024 |
| ASH Property Services Limited | Real estate | 2015 |
| ASH Tree Walk Management Limited | Households | 1970 |
| Asha Consultants Limited | Information & communication | 2018 |
| Ashbrook Business Solutions Limited | Professional & scientific | 2023 |
| Ashbury Computer Services Ltd | Information & communication | 2019 |