| Annabel Williams Music Limited | Arts & recreation | 2016 |
| Annexe Spaces UK Limited | Construction | 2022 |
| Anomalous Trading (UK) Ltd | Professional & scientific | 2025 |
| ANP Strategy Ltd | Professional & scientific | 2020 |
| Anpr Plus Limited | Information & communication | 2022 |
| Ansr Group UK Ltd | Real estate | 2024 |
| Answeruk Ltd | Administrative & support | 2017 |
| Antar Logtrans Ltd | Transport & logistics | 2025 |
| Antex Industrial (Europe) Ltd. | Wholesale & retail | 2000 |
| Anthea a G Antiques Limited | Wholesale & retail | 2002 |
| Anthobhis Health Care Ltd | Administrative & support | 2019 |
| Antholin Commodities Limited | Financial services | 2025 |
| Antholin Group Holdings Limited | Financial services | 2025 |
| Antholin Ltd | Information & communication | 2023 |
| Antiques Ant's Cleaning Services Limited | Administrative & support | 2020 |
| Antit Website Design & Development Limited | Information & communication | 2010 |
| Anukta Limited | Health & social care | 2021 |
| Anworth Close Management Limited | Households | 1982 |
| ANY Accident LLP | | 2012 |
| ANY Turbocharger Ltd | Wholesale & retail | 2022 |
| Anytecoh AI Limited | Information & communication | 2025 |
| AO Builders Ltd | Construction | 2025 |
| AO Hotels Group Ltd | Financial services | 2024 |
| AO Hotels Operations Ltd | Hospitality | 2024 |
| AO Hotels Services Ltd | Hospitality | 2024 |
| AOG Foundation Limited | Other services | 2009 |
| AP Emporium Ltd | Wholesale & retail | 2013 |
| AP EYE Health Ltd. | Health & social care | 2016 |
| AP Investments Ltd | Real estate | 2021 |
| AP Steelfixing Ltd | Construction | 2025 |
| Apart Realty Ltd | Professional & scientific | 2021 |
| APD IT Solutions Limited | Information & communication | 2021 |
| Apdp Limited | Health & social care | 2020 |
| APE Developments Ltd | Real estate | 2015 |
| Aperio Technologies Ltd | Other services | 2025 |
| Aperol Ltd | Real estate | 2020 |
| Apex AI Trading Limited | Wholesale & retail | 2026 |
| Apex Care Centre Limited | Health & social care | 2013 |
| Apex Care Holdings Limited | Other services | 2017 |
| Apex Data Services Limited | Information & communication | 2023 |
| Apex Distribution London Limited | Transport & logistics | 2018 |
| Apex International Media Limited | Wholesale & retail | 2005 |
| Apex LS Refurb Ltd | Construction | 2026 |
| Apex Meridian Property Ltd | Real estate | 2026 |
| Apex Productions Limited | Information & communication | 2014 |
| Apex Reproductive Health Care 117 Limited | Health & social care | 2024 |
| Apex Space Limited | Real estate | 2025 |
| Apex Spire Limited | Administrative & support | 2026 |
| APEX4WD Ltd | Wholesale & retail | 2024 |
| Apexa Investments Limited | Real estate | 2007 |
| Apexheights Limited | Real estate | 1992 |
| APG Restaurant Ltd | Hospitality | 2024 |
| Apical Properties Limited | Real estate | 2019 |
| APJ Accountancy Limited | Professional & scientific | 2011 |
| APM Interim Management Limited | Real estate | 2016 |
| Apollo Consultancy Services Ltd | Professional & scientific | 2021 |
| Apollo Energy (UK) PVT Ltd | Energy | 2025 |
| Apple Catering Hire Ltd | Hospitality | 2020 |
| Apple Property Group Ltd | Real estate | 2018 |
| Appleday Associates Limited | Professional & scientific | 2006 |
| Applelong Limited | Hospitality | 2018 |
| Appleton Business Centre Ltd | Real estate | 2009 |
| Applied Atomics Ltd. | Manufacturing | 2019 |
| Approach Peoples Recruitment Services Limited | Wholesale & retail | 2025 |
| APPSOURCE313 Consulting Ltd | Information & communication | 2026 |
| Aprirose Trading Holding Limited | Wholesale & retail | 2015 |
| Aprirose Trading Limited | Wholesale & retail | 2001 |
| Aprop West Hampstead Ltd | Real estate | 2026 |
| APS Meats (1979) Limited | Wholesale & retail | 2020 |
| Apta AI Ltd | Information & communication | 2026 |
| Aqua Blue-Flame Ltd | Construction | 2014 |
| Aqua Engineering Ltd | Professional & scientific | 2024 |
| Aqua Fish & Chips Ltd | Hospitality | 2024 |
| Aqua International Limited | Real estate | 2024 |
| Aquafaba Limited | Real estate | 2019 |
| Aquarius Five Capital Ltd | Financial services | 2024 |
| Aquavista Properties Limited | Real estate | 2025 |
| Aquila Heating Services Ltd | Construction | 2018 |
| Aquum Ltd | Hospitality | 2008 |
| AR Hair & Cosmetics Ltd | Wholesale & retail | 2020 |
| AR Sells Ltd | Wholesale & retail | 2022 |
| Ar-Ha Ltd | Professional & scientific | 2011 |
| ARA Consulting Services Limited | Professional & scientific | 2025 |
| Arabico London Ltd | Real estate | 2024 |
| Aragon Park Management Limited | Real estate | 2005 |
| Arajy Properties Ltd | Real estate | 2023 |
| Aral Property Investment Ltd | Real estate | 2023 |
| Aranya Consulting Limited | Professional & scientific | 2017 |
| Aras IST Ltd | Wholesale & retail | 2023 |
| Arason Imports Ltd | Wholesale & retail | 2020 |
| Arboreal Architecture Limited | Professional & scientific | 2007 |
| Arborescence Montessori Ltd | Education | 2017 |
| Arbra Homes Ltd | Other services | 2025 |
| Arbra Proper Services Ltd | Financial services | 2024 |
| Arbra Properties Ltd | Real estate | 2025 |
| ARC Inspections Ltd | Construction | 2023 |
| ARC UK Properties Ltd | Real estate | 2025 |
| Arc-Trix Limited | Professional & scientific | 2025 |
| Arcatype Consultancy Limited | Administrative & support | 2017 |
| Arch Cost Consultancy Limited | Professional & scientific | 2022 |