| AOG Logistics Ltd | Transport & logistics | 2023 |
| Aozm Hospitality Limited | Hospitality | 2025 |
| APB Training Services Ltd | Professional & scientific | 2021 |
| Apeksh Limited | Real estate | 2022 |
| Apetrop Limited | Extraterritorial | 2013 |
| Apex Accounting Services Ltd | Professional & scientific | 2020 |
| Apex Beech Digital Ltd | Professional & scientific | 2025 |
| Apex Flow Consulting Ltd | Construction | 2026 |
| Apex Home Surveys Ltd | Professional & scientific | 2024 |
| Apex Mindset Ltd | Education | 2019 |
| Apex Performance Consulting Ltd | Arts & recreation | 2021 |
| Apex SPX Ltd | Arts & recreation | 2026 |
| Apexira Solutions Ltd | Wholesale & retail | 2025 |
| Apfx Ltd | Professional & scientific | 2015 |
| APH Decorating Services Ltd | Construction | 2011 |
| Aphilian Electrical Services Limited | Construction | 2007 |
| Apilly Ltd | Information & communication | 2026 |
| Aplix Fasteners U.K. Limited | Wholesale & retail | 1985 |
| Apollo K Productions Ltd | Manufacturing | 2022 |
| Apollo Publishing Limited | Information & communication | 2025 |
| App Roofing Ltd | Construction | 2017 |
| Apps Building Solutions Limited | Construction | 2008 |
| APS Pool Technics Ltd | Other services | 2016 |
| Apsky Limited | Hospitality | 2025 |
| Aptus Wealth Limited | Financial services | 2012 |
| Apulum Services Limited | Information & communication | 2013 |
| Aqesha Aesthetics and Beauty Ltd | Other services | 2026 |
| Aqms Electrical Ltd | Manufacturing | 2022 |
| Aqua Clear Solutions Ltd | Administrative & support | 2015 |
| Aqua-Sol Ingredients Ltd | Wholesale & retail | 2012 |
| Aqua-Sol Products Ltd | Extraterritorial | 2012 |
| Aquaclean Fabrics Limited | Wholesale & retail | 2006 |
| Aquila Procurement Services Ltd | Professional & scientific | 2017 |
| Aqwace Ltd | Professional & scientific | 2019 |
| Arazu Construction Ltd | Construction | 2020 |
| Arbitra Technologies Ltd | Information & communication | 2024 |
| ARC Media Productions Ltd | Information & communication | 2020 |
| Arcana Living Ltd | Wholesale & retail | 2022 |
| Archistrategy Limited | Professional & scientific | 2014 |
| Arctec Solutions Ltd | Information & communication | 2017 |
| ARD Aviation Services (Horsham) Ltd | Transport & logistics | 2022 |
| Ards Aviation Training Ltd | Professional & scientific | 2024 |
| ARE WE Wayward Holdco Limited | Administrative & support | 2024 |
| ARE WE Wayward Limited | Financial services | 2022 |
| Arelle Products Limited | Wholesale & retail | 2001 |
| Arena Catering Limited | Hospitality | 1998 |
| Arena Consulting Ltd | Professional & scientific | 2016 |
| Arenas Healthcare Services Limited | Health & social care | 2009 |
| Arenza Limited | Professional & scientific | 2005 |
| ARH Cost Consultancy Limited | Professional & scientific | 2022 |
| Arhstudio Ltd | Professional & scientific | 2026 |
| Aridan Ltd | Households | 2019 |
| Arion Consultancy Limited | Professional & scientific | 2019 |
| ARK Sports Management Limited | Arts & recreation | 2024 |
| Armc Global Trading Company Ltd | Wholesale & retail | 2026 |
| Armor Vision (UK) Limited | Wholesale & retail | 2022 |
| Arodene Developments Limited | Construction | 2021 |
| Aroma Collection Ltd | Wholesale & retail | 2023 |
| ARP People Consultancy Ltd | Professional & scientific | 2021 |
| Arrancourt Management Company Limited | Households | 1981 |
| Arrowsocks Limited | Wholesale & retail | 2017 |
| Art-I-Check Ltd | Information & communication | 2012 |
| Artairnyx Ltd | Wholesale & retail | 2025 |
| Artelesi Ltd | Hospitality | 2025 |
| Artemis Software Solutions Limited | Information & communication | 2019 |
| Artifact Art Limited | Information & communication | 2021 |
| Artifact Entertainment Limited | Information & communication | 2021 |
| Artifact Platform Limited | Information & communication | 2021 |
| Artificial Intelligence Implementation Ltd | Public administration | 2026 |
| Artillery One Limited | Real estate | 2003 |
| Artillery Two Limited | Real estate | 2003 |
| Artrix Aesthetics Clinic Ltd | Other services | 2023 |
| Arts Encompassed Ltd | Arts & recreation | 2021 |
| Arun Automotive Limited | Wholesale & retail | 2020 |
| Arun Business Consortium Ltd | Administrative & support | 2009 |
| Arun Court Horsham RTM Company Limited | Households | 2026 |
| Arun Developments Limited | Construction | 1973 |
| Arun Ecology Ltd | Professional & scientific | 2020 |
| Arun Estate Agencies Limited | Administrative & support | 1991 |
| Arun Gardens (Horsham) Management Company Limited | Households | 2009 |
| Arun Leasing Company Limited | Administrative & support | 1997 |
| Arun Management Co. Limited | Households | 1982 |
| Arun Property Investments Limited | Real estate | 1998 |
| Arun Surveying Limited | Professional & scientific | 1994 |
| Arundale Walk Residents Management Company Limited | Households | 2015 |
| ARX AI Ltd | Professional & scientific | 2020 |
| ARX Music Ltd | Information & communication | 2026 |
| Aryarodi Ltd | Hospitality | 2021 |
| Asad Footcare Ltd | Health & social care | 2023 |
| Ascend Developments Limited | Construction | 2012 |
| Ascendant Research Holdings Ltd | Construction | 2020 |
| Ascended Medical Aesthetics Limited | Health & social care | 2026 |
| Ascent Europe Limited | Information & communication | 2018 |
| Ascent FS Ltd | Professional & scientific | 2009 |
| Ascot Care Ltd. | Health & social care | 2005 |
| ASG Process Solutions Ltd | Professional & scientific | 2018 |
| Ashbrook Planning Limited | Professional & scientific | 2018 |
| Ashbury Services Limited | Administrative & support | 2025 |
| Ashe Consulting Limited | Administrative & support | 2007 |
| Ashe Properties Ltd | Real estate | 2019 |