| Annur EN Limited | Hospitality | 2014 |
| Anog Energy Limited | Mining & quarrying | 2015 |
| Anointing Cleaning Services Limited | Administrative & support | 2018 |
| Anson Capital Ltd | Financial services | 2026 |
| ANT Accounting Ltd | Professional & scientific | 2020 |
| Anthology Vintage Hire Limited | Administrative & support | 2018 |
| Anthony Elston Limited | Health & social care | 1994 |
| Anthony Woodward Consulting Limited | Professional & scientific | 2024 |
| Anthoria Homes Limited | Real estate | 2024 |
| Anthrorg Ltd | Professional & scientific | 2023 |
| Antique Britannia Ltd | Wholesale & retail | 2025 |
| Antonio Bonanno Diamond Setter Ltd | Manufacturing | 2026 |
| ANU Baba Ltd | Wholesale & retail | 2023 |
| Anutra Retail Hub Ltd | Wholesale & retail | 2025 |
| ANY and ALL Services Limited | Administrative & support | 2020 |
| AO Medical Limited | Health & social care | 2018 |
| Aob-Custom Kicks Limited | Manufacturing | 2022 |
| AOL Sourcing and Support Services Ltd | Professional & scientific | 2019 |
| AP Advisory Services Ltd | Professional & scientific | 2026 |
| AP Engineering (UK) Ltd | Manufacturing | 2002 |
| AP GAS & Plumbing Services Limited | Construction | 2012 |
| AP JET Wash Ltd | Other services | 2023 |
| Apab Limited | Administrative & support | 2005 |
| Apache Landscapes and Building Ltd | Construction | 2026 |
| Aparker's Properties Ltd | Real estate | 2025 |
| APB Caravans Ltd | Wholesale & retail | 2024 |
| APB Law Limited | Professional & scientific | 2015 |
| APB Marine Limited | Professional & scientific | 2009 |
| APB Rentals Limited | Real estate | 2024 |
| APB Yacht Surveys Limited | Professional & scientific | 2016 |
| APC Scaffold Limited | Construction | 2019 |
| Apco Contracts Limited | Manufacturing | 2004 |
| APD IT Consulting Ltd | Information & communication | 2008 |
| Apertus Consulting Limited | Professional & scientific | 2024 |
| Apertus Mind Limited | Health & social care | 2023 |
| Apertus View Limited | Professional & scientific | 2023 |
| Apex Climate Ltd | Construction | 2026 |
| Apex Electrical Services Ltd | Construction | 2017 |
| Apex Estates and Facilities Ltd | Construction | 2025 |
| Apex Event Solutions Limited | Education | 2024 |
| Apex Overseas Limited | Wholesale & retail | 2025 |
| Apex Prime Care (IOW) Ltd | Health & social care | 2019 |
| Apex Prime Care East Ltd | Health & social care | 2010 |
| Apex Prime Care Group Ltd | Financial services | 2020 |
| Apex Prime Care Holdings Ltd | Health & social care | 2021 |
| Apex Prime Care North Limited | Health & social care | 2019 |
| Apex Prime Care West Ltd | Health & social care | 2004 |
| Apex QA Solutions Ltd | Information & communication | 2026 |
| Apex Recruit Ltd | Administrative & support | 2024 |
| Apex Safety Solutions Ltd | Professional & scientific | 2012 |
| Apex Training and Management Ltd. | Real estate | 2018 |
| Apexbeat Ltd | Real estate | 2018 |
| Apexx Group Ltd | Wholesale & retail | 2026 |
| APG General Builders Limited | Construction | 2019 |
| APH Contract Cleaners Limited | Administrative & support | 2013 |
| API Motors Ltd | Wholesale & retail | 2015 |
| Apisense Ltd | Extraterritorial | 2022 |
| APL Roofing & Maintenance Services Limited | Construction | 2021 |
| Apll Properties Limited | Real estate | 2020 |
| APM Online Retail Limited | Wholesale & retail | 2025 |
| Apmi Ltd | Information & communication | 2010 |
| Apollo Advertising Limited | Administrative & support | 2013 |
| Apollo Electrical (South East) Ltd | Construction | 2022 |
| Apollo Forklift UK Limited | Wholesale & retail | 2026 |
| Apollo Renewable’S Ltd | Construction | 2022 |
| Apollo Volt Ltd | Construction | 2024 |
| APP2DEV Ltd | Information & communication | 2025 |
| Apparent Wind Ltd | Professional & scientific | 2018 |
| Appius Claudius Ltd | Real estate | 2025 |
| Apple Tree Cake Design Limited | Hospitality | 2012 |
| Appleby Wealth Management Ltd | Financial services | 2018 |
| Appleday Enterprises Limited | Financial services | 1976 |
| Apples and Chairs Limited | Administrative & support | 2017 |
| Appleseed Communications Ltd | Construction | 2018 |
| Appleyard Group Limited | Professional & scientific | 1923 |
| Appliance Repairman Ltd | Other services | 2023 |
| Applied Lighting Solutions Limited | Wholesale & retail | 1990 |
| Appocrates Ltd | Information & communication | 2026 |
| Appointed Representative 1 Limited | Financial services | 2015 |
| Appstick Solutions Ltd | Information & communication | 2024 |
| Apputee Ltd | Health & social care | 2022 |
| APR Digger Hire Ltd | Administrative & support | 2024 |
| APS Roofing Services Ltd | Construction | 2025 |
| APS Technocrats UK Limited T/A Apstechs UK Ltd | Construction | 2019 |
| Apsley Estates Limited | Professional & scientific | 2000 |
| Apstechs Infra Ltd | Professional & scientific | 2022 |
| APT Holdings Limited | Agriculture & fishing | 2003 |
| APT Infrastructure Ltd | Administrative & support | 2019 |
| APT Philpot Limited | Construction | 2016 |
| APW Contracts Ltd | Construction | 2008 |
| APW TM Solutions Limited | Construction | 2016 |
| Aqua Blasters Limited | Administrative & support | 2019 |
| Aqua Clean Cleaning Services Ltd | Administrative & support | 2025 |
| Aquamercantile Holdings Limited | Financial services | 2022 |
| Aquamercantile Limited | Financial services | 1999 |
| Aquasei Ltd | Manufacturing | 2024 |
| Aquasulis Limited | Health & social care | 2019 |
| Aquitaine Strategy Limited | Administrative & support | 2016 |
| Arabico Ltd | Professional & scientific | 2024 |
| Arach Estates Limited | Real estate | 2017 |