| Apex Rail Advisory Limited | Professional & scientific | 2026 |
| Apjoinery & Carpentry Ltd | Manufacturing | 2016 |
| APL Community Services CIC | Hospitality | 2024 |
| APL Leaseco CIC | Hospitality | 2024 |
| APN Real Estate Limited | Real estate | 2019 |
| Apollo Buckingham Health Sciences Campus Limited | Administrative & support | 2017 |
| Apollo Education UK Limited | Administrative & support | 2018 |
| Apollo Radiology International Limited | Health & social care | 2006 |
| Apos Crewe Ltd | Hospitality | 2018 |
| Apos Kebab House (Nantwich) Ltd | Other services | 2018 |
| App Girodisc Limited | Wholesale & retail | 2026 |
| Appease Ltd | Information & communication | 2014 |
| Applebright Coaching Limited | Professional & scientific | 2026 |
| Appleseed Bidco Limited | Administrative & support | 2014 |
| Appleseed Holdco Limited | Administrative & support | 2014 |
| Applied Software Engineering Limited | Information & communication | 1999 |
| Apptonic Solutions Ltd | Information & communication | 2012 |
| Appy Fleet Limited | Extraterritorial | 2016 |
| Appy Risk Technologies Limited | Administrative & support | 2016 |
| APX Engineering Ltd | Professional & scientific | 2026 |
| Aqua Global Ltd | Health & social care | 2025 |
| Aqua Massage Therapy Ltd | Other services | 2021 |
| Aquaflow Limited | Extraterritorial | 2006 |
| Aquatic Trade Imports Ltd | Wholesale & retail | 2025 |
| Aquila Transport Limited | Transport & logistics | 2023 |
| AR Mobile Mechanics Ltd | Wholesale & retail | 2023 |
| AR Walks Ltd | Agriculture & fishing | 2024 |
| Aram Property Holding Ltd | Real estate | 2026 |
| Arbennig Properties Limited | Real estate | 2022 |
| Arboriculture Solutions Ltd | Agriculture & fishing | 2024 |
| ARC Mechanical Services Ltd | Professional & scientific | 2026 |
| Arca Biologistics Limited | Transport & logistics | 2023 |
| Arch Publications Limited | Information & communication | 2017 |
| Archer Technical Services Limited | Professional & scientific | 2013 |
| Architectural Planning Partnership LLP | | 2009 |
| Arclid Property Services Limited | Real estate | 2024 |
| Arctec Group Limited | Financial services | 2021 |
| ARD Property Group Ltd | Real estate | 2020 |
| Ardon (Painting Contractors) Limited | | 1945 |
| Area 51 Gym Limited | Arts & recreation | 2014 |
| Arema One Ltd | Wholesale & retail | 2026 |
| Arley Wealth Management Limited | Administrative & support | 2017 |
| Armstrong Plant Hire and Sales Limited | Administrative & support | 2024 |
| Aron Tyler Farrier Limited | Other services | 2014 |
| Aropl Studios Ltd | Information & communication | 2021 |
| Around Tenby Ltd | Administrative & support | 2024 |
| ARP Polishing Ltd | Administrative & support | 2025 |
| ARR Solutions Ltd | Information & communication | 2013 |
| Arrowscroft Ltd | Financial services | 2011 |
| Arrowscroft Properties Ltd | Real estate | 2024 |
| Arslan Enterprises Ltd | Real estate | 2018 |
| Art by Steph Christie Ltd | Arts & recreation | 2025 |
| Artech Innovations Limited | Wholesale & retail | 2019 |
| Artgreg Limited | Construction | 2024 |
| ARW Sales and Marketing Ltd | Wholesale & retail | 2024 |
| Arwens PAW Retreat Ltd | Other services | 2026 |
| AS Crewe Ltd | Real estate | 2020 |
| AS Explore Outdoor Limited | Arts & recreation | 2014 |
| AS Express Couriers Limited | Transport & logistics | 2024 |
| AS20GATEFIELDST Ltd | Real estate | 2020 |
| ASA Steel Structures Limited | Manufacturing | 1987 |
| Ascent Acquisitions Consultancy Limited | Professional & scientific | 2024 |
| Ascent Acquisitions Group Ltd | Information & communication | 2023 |
| Ascent Lift Consultancy Ltd | Professional & scientific | 2012 |
| Asfab Washroom Systems Ltd | Construction | 2019 |
| Ashfields Farm Limited | Agriculture & fishing | 2008 |
| Ashfords Associates Limited | Health & social care | 2025 |
| Ashley Electrics Limited | Construction | 2005 |
| Ashley House Private Limited | Real estate | 2016 |
| Ashley Plant and Groundworks Limited | Construction | 2018 |
| Asim Jani Electrical Limited | Construction | 2015 |
| ASM Accounting Ltd | Professional & scientific | 2018 |
| ASM Build Ltd | Construction | 2025 |
| Asphalt Re-Lay Limited | Wholesale & retail | 2007 |
| Aspirar Associates Limited | Professional & scientific | 2025 |
| Aspire FC Ltd | Education | 2024 |
| Asservio Limited | Education | 2013 |
| Asset Realisation Group Limited | Other services | 2022 |
| Asset Trading Limited | Other services | 2025 |
| Assurant Co. (PG UK), Ltd | Other services | 2020 |
| Assurant Co., Ltd. | Professional & scientific | 2015 |
| Assurant Device Care Limited | Administrative & support | 2009 |
| Assurant Direct Limited | Financial services | 2005 |
| Assurant General Insurance Limited | Financial services | 1989 |
| Assurant Group Limited | Professional & scientific | 1996 |
| Assurant Intermediary Limited | Financial services | 2000 |
| Astley Way Dairy Limited | Manufacturing | 2026 |
| Astonishing Paving Ltd | Construction | 2020 |
| Astonvisa Ltd | Wholesale & retail | 2023 |
| Astra Management Services Limited | Professional & scientific | 1997 |
| AT Property Management Ltd | Real estate | 2025 |
| AT Telecom Ltd | Wholesale & retail | 2010 |
| Atex Training Ltd | Education | 2026 |
| Athelney Campaigns Ltd | Administrative & support | 2024 |
| Athlete Access Limited | Professional & scientific | 2025 |
| Atkins Commercial Services Ltd | Other services | 2012 |
| Atlantic Titan Ltd | Wholesale & retail | 2026 |
| Atlantic View Developments Limited | Real estate | 2018 |
| Atlas Business Group of Companies Limited | Information & communication | 1996 |
| Atlas Business Software & Technologies Ltd | Extraterritorial | 2009 |