| Anzhi Consult Ltd | Construction | 2021 |
| AP CAD Ltd | Construction | 2018 |
| Apcoa Facilities Management (Harrow) Limited | Administrative & support | 1997 |
| Apcoa Facilities Management (UK) Limited | Administrative & support | 1989 |
| Apcoa Parking (UK) Limited | Administrative & support | 1991 |
| Apcoa Parking Holdings (UK) Limited | Administrative & support | 2004 |
| Apcoa Parking Services (UK) Limited | Administrative & support | 1990 |
| Apex Learning Centre Ltd | Education | 2026 |
| Apex Packaging Ltd | Wholesale & retail | 2025 |
| Apex Property Hub Ltd | Real estate | 2025 |
| Apex Structural Engineer Consultants Ltd | Professional & scientific | 2025 |
| Apexbuild Contractors Limited | Construction | 2019 |
| Apexcy International Trade Ltd | Construction | 2024 |
| Apexhaven Investments Limited | Real estate | 2025 |
| APH Telecom Services Ltd | Information & communication | 2026 |
| Apjc Consultancy Ltd | Professional & scientific | 2025 |
| Apna Ghar Properties Ltd | Real estate | 2020 |
| Apna Punjab Mithai Ltd | Hospitality | 2019 |
| Apontesbuilders Ltd | Construction | 2022 |
| App Transports Limited | Transport & logistics | 2021 |
| Appily Ltd | Information & communication | 2023 |
| Apple House Guesthouse Ltd | Hospitality | 2014 |
| Applenet Care & Support Ltd | Administrative & support | 2020 |
| Applied Cloud Limited | Information & communication | 2023 |
| Applied Logiq Ltd | Professional & scientific | 2002 |
| Appollo Trading Ltd | Wholesale & retail | 2022 |
| APPS4ENGINEERING Ltd | Manufacturing | 2025 |
| APQ Locations Ltd | Professional & scientific | 2023 |
| Apra Holdings Ltd | Financial services | 2023 |
| Apra Properties Group Ltd | Real estate | 2023 |
| Apram Homes Limited | Real estate | 2025 |
| Aprojectlondon Ltd | Construction | 2025 |
| APS Motor Group Limited | Wholesale & retail | 2024 |
| APT Forwarding Ltd | Transport & logistics | 2023 |
| APT Traders Ltd | Wholesale & retail | 2025 |
| APW Leisure Limited | Administrative & support | 2013 |
| Aqua Carpatica UK Ltd | Wholesale & retail | 2018 |
| Aqua Launderette Ltd | Other services | 2024 |
| Aquaarios 1 Limited | Professional & scientific | 2018 |
| Aquanet Trading Ltd | Professional & scientific | 2022 |
| Aquarios Consulting Ltd | Administrative & support | 2018 |
| Aquarius Property Services Ltd | Households | 2025 |
| Aquasense (UK) Limited | Agriculture & fishing | 2013 |
| Aquila Technology Limited | Other services | 2011 |
| AR Solutions (UK) Limited | Professional & scientific | 2013 |
| Ar&Triplea Ltd | Hospitality | 2024 |
| ARA Catering Ltd | Hospitality | 2017 |
| Araam Limited | Hospitality | 2025 |
| Araba Cars Ltd | Wholesale & retail | 2025 |
| Arabian Knight OUD Ltd | Wholesale & retail | 2023 |
| Arali Properties Limited | Real estate | 2021 |
| Aralu Limited | Wholesale & retail | 2024 |
| Arbi Enterprise Ltd | Wholesale & retail | 2025 |
| ARC Padel Limited | Arts & recreation | 2025 |
| Archana RAO Dermatology Limited | Health & social care | 2022 |
| Archer Close Management Company Limited | Households | 1989 |
| Architecture Innovation and Research Ltd | Professional & scientific | 2023 |
| Arco Iris Limited | Wholesale & retail | 2000 |
| Arco Management Limited | Other services | 2025 |
| Arcquility IT Solutions Limited | Other services | 2024 |
| Arcranium Ltd | Wholesale & retail | 2022 |
| Ard.Com (UK) Limited | Wholesale & retail | 2010 |
| Arden 51 Ltd | Real estate | 2023 |
| Ardenstone Holdings Ltd | Financial services | 2026 |
| Ardern Court Management Company Limited | Professional & scientific | 1989 |
| ARE YOU Jerkin' Ltd | Hospitality | 2025 |
| Arena Group Holdings Limited | Professional & scientific | 1999 |
| Arena Group Limited | Administrative & support | 1987 |
| Arenaeq Limited | Agriculture & fishing | 2021 |
| Arenco Ltd | Wholesale & retail | 2025 |
| Arete Aerospace Engineering Ltd | Professional & scientific | 2026 |
| Argyle Court RTE Company Ltd | Households | 2004 |
| ARI (Emea) Limited | Information & communication | 2025 |
| ARI Pharm Ltd | Wholesale & retail | 2021 |
| Aria 88 Cars Limited | Administrative & support | 2021 |
| Aria Global Services Ltd | Financial services | 2016 |
| Aria Hair and Beauty Salon Limited | Other services | 2025 |
| Arimas Consulting Ltd | Professional & scientific | 2020 |
| Aripra Ltd | Construction | 2018 |
| Arise and Shine Care Services Ltd | Administrative & support | 2009 |
| Arjan Estates Ltd | Real estate | 2024 |
| Arjan Homes Ltd | Real estate | 2025 |
| Arjun Sharma Limited | Information & communication | 2010 |
| ARK Corporation Ltd | Real estate | 2025 |
| Arkk Enterprises Limited | Professional & scientific | 2019 |
| Arlea B Limited | Wholesale & retail | 2024 |
| Arlesey House Maintenance Company Limited | Households | 1986 |
| ARM City Living Ltd | Real estate | 2020 |
| Armaf (UK) Ltd | Wholesale & retail | 2019 |
| Armas Group Ltd | Wholesale & retail | 2019 |
| Armford Estates Limited | Real estate | 2023 |
| Armford Leisure Limited | Wholesale & retail | 2026 |
| Armitage and Rigby Limited | Extraterritorial | 1953 |
| Armonia Cruise Limited | Transport & logistics | 2025 |
| Armstrong (U.K.) Investments | Professional & scientific | 1996 |
| Arnab Ltd | Hospitality | 2017 |
| Arnellan House (Management) Limited | Real estate | 1966 |
| Arnold and Anderson Investments Limited | Hospitality | 2019 |
| Aron Restore Solutions Ltd | Wholesale & retail | 2025 |
| Arorabrotherss Limited | Real estate | 2026 |