| Arrow Connect Ltd | Transport & logistics | 2023 |
| ARS (Stoke on Trent) Limited | Transport & logistics | 2008 |
| ARS Developer Ltd | Information & communication | 2026 |
| Arshia and Daughters Limited | Health & social care | 2023 |
| Arslan K Traders Ltd | Wholesale & retail | 2024 |
| Arslan Zahid Innovations Ltd | Information & communication | 2024 |
| Art New Construction Ltd | Construction | 2024 |
| Art Tiler Ltd | Construction | 2022 |
| Artem Mechanical Services Ltd | Professional & scientific | 2022 |
| Arten Homes Limited | Real estate | 2019 |
| Arthur Henry Catering Ltd | Hospitality | 2022 |
| Arthur Leonard Limited | Wholesale & retail | 2016 |
| Arthur Sneyd Private Hire Ltd | Transport & logistics | 2025 |
| Artico & Co Developments Limited | Construction | 2024 |
| Articulate.Xyz Ltd | Information & communication | 2017 |
| Artisan INK Limited | Other services | 2024 |
| Artiste Beauty Limited | Wholesale & retail | 2017 |
| Artistic Consultancy Limited | Administrative & support | 2026 |
| Artj Construction Ltd | Construction | 2023 |
| Artwork International Services Limited | Other services | 2003 |
| Arzu Limited | Wholesale & retail | 2013 |
| AS Letting Ltd | Real estate | 2023 |
| AS Hydraulics U.K. Ltd | Wholesale & retail | 2021 |
| AS One (Enablement Services) CIC | Administrative & support | 2018 |
| AS Topco Limited | Financial services | 2021 |
| ASA (Holdings) Limited | Other services | 1997 |
| ASA Fabrications Ltd | Manufacturing | 2022 |
| ASA Fabs Ltd | Manufacturing | 2011 |
| ASA Special Projects Limited | Manufacturing | 2018 |
| Asad Homes & Services Ltd | Agriculture & fishing | 2026 |
| Asad Nisar Ltd | Wholesale & retail | 2025 |
| Asads Properties Limited | Real estate | 2026 |
| ASB Electrical Ltd | Construction | 2025 |
| Asbestos Roof Renewal Ltd | Construction | 2021 |
| Asbestos Training Solutions Limited | Professional & scientific | 2012 |
| ASC Industrial Products Ltd | Wholesale & retail | 2009 |
| ASC Lift Engineering Services Limited | Manufacturing | 2021 |
| Ascendancy Training Ltd | Education | 2020 |
| Ascendia Training Academy Ltd | Education | 2026 |
| Ascroft Transport Limited | Transport & logistics | 1994 |
| Asdil Ltd | Transport & logistics | 2019 |
| Asgard Security Ltd | Administrative & support | 2022 |
| ASH Bank Garage Limited | Wholesale & retail | 1985 |
| ASH Hall Limited | Health & social care | 2010 |
| ASH House Global Group Ltd | Financial services | 2020 |
| ASH House Investment Limited | Construction | 2013 |
| ASH House Properties Ltd | Real estate | 2019 |
| Ashahab Ltd | Wholesale & retail | 2026 |
| Ashaz Sultan Ltd | Wholesale & retail | 2025 |
| Ashco Groundwork Contractors Limited | Administrative & support | 2025 |
| Ashcroft Process Equipment Limited | Manufacturing | 2010 |
| Ashes Clothing Ltd | Wholesale & retail | 2017 |
| Ashese Store Ltd | Wholesale & retail | 2025 |
| Ashford Business Services Ltd | Other services | 2023 |
| Ashford Nashta Ltd | Hospitality | 2022 |
| Ashgreen Homes Limited | Construction | 2004 |
| Ashlands Construction Limited | Construction | 2017 |
| Ashleigh's Builders Ltd | Construction | 2004 |
| Ashley Change Consultancy Limited | Professional & scientific | 2023 |
| Ashlow Braces Limited | Health & social care | 2017 |
| Ashlow Orthodontics Limited | Health & social care | 2018 |
| Ashspire Ltd | Education | 2025 |
| Ashton Contract Services Ltd | Construction | 2025 |
| Ashton Geology Limited | Professional & scientific | 1982 |
| ASIF786 Ltd | Real estate | 2021 |
| Asimcrafts Ltd | Wholesale & retail | 2026 |
| ASJ Automotive Ltd | Wholesale & retail | 2022 |
| ASK & MM Ltd | Wholesale & retail | 2025 |
| ASK Equip Ltd | Other services | 2019 |
| Askari Construction Limited | Construction | 2026 |
| Askey & Sutcliffe Associates Limited | Financial services | 2004 |
| Askmo Limited | Professional & scientific | 2024 |
| Aslam Asset Management Ltd | Construction | 2026 |
| ASM Sports (UK) Limited | Education | 2010 |
| Asman Properties Limited | Real estate | 2019 |
| Asnf Network Ltd | Other services | 2017 |
| Aspect (Plan-Design-Construct) Ltd | Construction | 2022 |
| Aspire Carpentry and Joinery Ltd | Construction | 2012 |
| Aspire Executive Coaching Ltd. | Education | 2020 |
| Aspire Sports International Limited | Wholesale & retail | 2025 |
| Aspire Support Services Ltd | Health & social care | 2021 |
| Aspiring Solutions Ltd | Professional & scientific | 2019 |
| Asps Logistics Ltd | Transport & logistics | 2017 |
| Asriyah Ltd | Wholesale & retail | 2024 |
| Assassinz Ltd | Wholesale & retail | 2023 |
| Associated Calibration & Training Limited | Professional & scientific | 2001 |
| Associated Pneumatic Industries Limited | Manufacturing | 2024 |
| Assured BK Ltd | Professional & scientific | 2024 |
| Assured Building Solutions (SOT) Ltd | Construction | 2022 |
| Assured Electrical (Installation and Testing) Limited | Manufacturing | 2014 |
| Assured Electrical Services (Staffs) Ltd | Construction | 2011 |
| Assured Lettings and Sales Ltd | Real estate | 2025 |
| Assured Maintenance Ltd | Construction | 2026 |
| Assured Packaging Limited | Manufacturing | 2009 |
| Assured Properties (SOT) Ltd | Real estate | 2025 |
| Astbury Car Sales Limited | Wholesale & retail | 1997 |
| Astec Assistive Technology Solutions Ltd | Information & communication | 2012 |
| Aston Eco Limited | Professional & scientific | 2021 |
| Aston Farnshaw Limited | | 2014 |
| Aston Green Limited | Extraterritorial | 1993 |