| Aravindan Ltd | Information & communication | 2024 |
| ARC Access Ltd | Construction | 2022 |
| Arcadia Property Developments Ltd | Construction | 2025 |
| Archeus Karma BIO Ltd | Wholesale & retail | 2026 |
| Architectural Installations Ltd | Other services | 2014 |
| Arcvik Solutions Ltd | Information & communication | 2012 |
| ARD Therapies Limited | Health & social care | 2014 |
| Ardelean Group Limited | Construction | 2018 |
| Ardem Enterprise Ltd | Other services | 2015 |
| Ardit Painters & Decorators Ltd | Construction | 2018 |
| Aredro Ltd | Wholesale & retail | 2022 |
| Arete Bookkeeping Ltd | Professional & scientific | 2026 |
| Arete Projects Limited | Other services | 2025 |
| Arethusa Upnor Ltd | Construction | 2017 |
| ARG Property Venture Ltd | Real estate | 2024 |
| ARI Investments Ltd | Real estate | 2016 |
| Arianna Expert Research & Consultancy Ltd | Professional & scientific | 2010 |
| ARK Living Homes Ltd | Real estate | 2023 |
| ARK Traders Ltd | Financial services | 2011 |
| Arlos Refurbishment Ltd | Real estate | 2023 |
| Armadillo Spirits Ltd | Wholesale & retail | 2016 |
| Armanu Drylining Ltd | Construction | 2016 |
| Armata Transport Limited | Transport & logistics | 2023 |
| Armond Roofing Ltd | Construction | 2023 |
| Armour Ltd | Manufacturing | 2023 |
| Arnold & Walker Event Services Limited | Administrative & support | 2013 |
| Arnold Logistics (UK) Ltd. | Transport & logistics | 2005 |
| Aroma Enterprises (UK) Limited | Wholesale & retail | 2008 |
| Aroma Fragrances Ltd | Manufacturing | 2025 |
| Arora Products Ltd | Wholesale & retail | 2024 |
| Arsene Catalin Limited | Transport & logistics | 2025 |
| Art Ever After Ltd | Wholesale & retail | 2014 |
| Art for MED C.I.C. | Health & social care | 2025 |
| Art Transport Logistics Ltd | Transport & logistics | 2026 |
| Artemis & Meade Ltd | Professional & scientific | 2013 |
| Arteseum Ltd | Households | 2016 |
| Artful Moments Ltd | Arts & recreation | 2025 |
| Arthur LEE Commercials Ltd | Wholesale & retail | 2024 |
| Artisan Print Services Ltd | Manufacturing | 2004 |
| Artist Surfaces Fine Art Delivery Limited | Transport & logistics | 2022 |
| Artist Surfaces Limited | Manufacturing | 2019 |
| Artlarry Ltd | Wholesale & retail | 2021 |
| ARU Homes Ltd | Real estate | 2015 |
| Arvelin Ltd | Real estate | 2026 |
| Arya K R Investments Limited | Hospitality | 2019 |
| Arya Kaur RAI Holdings Limited | Real estate | 2021 |
| Arya Supermarket Limited | Wholesale & retail | 2019 |
| ASA Enableus Services (Care and Support) Limited | Health & social care | 2025 |
| Asales Ltd | Wholesale & retail | 2024 |
| ASB Building Limited | Construction | 2019 |
| Asbo Performance Ltd | Extraterritorial | 2023 |
| ASC 10 Ltd | Real estate | 2018 |
| ASC Tuning Ltd | Wholesale & retail | 2024 |
| Ascend Global Consultancy Ltd | Information & communication | 2024 |
| Ascot Drylining Ltd | Construction | 2010 |
| ASD Learning (Midlands) Ltd | Education | 2012 |
| ASD Learning Limited | Education | 2006 |
| Asesewa Market Ltd | Wholesale & retail | 2026 |
| ASG Hire Ltd | Construction | 2015 |
| ASG Services Ltd | Construction | 2025 |
| Asgard Logistics Ltd | Transport & logistics | 2025 |
| Asgard Projects Limited | Construction | 2017 |
| ASH BEE Cloud Ltd | Information & communication | 2025 |
| ASH BEE Courier Ltd | Transport & logistics | 2026 |
| ASH BEE Tech Solutions Ltd | Information & communication | 2025 |
| Ashdown Management (Folkestone) Limited | Households | 1996 |
| Ashkent Plant Hire Ltd | Administrative & support | 2021 |
| Ashley Down Care Home Limited | Health & social care | 2004 |
| Ashmere Farms Limited | Agriculture & fishing | 1996 |
| Ashmere Holdings Limited | Construction | 2024 |
| Ashmere Property Developments Limited | Construction | 2026 |
| Ashmore Accountancy Limited | Professional & scientific | 2023 |
| Ashnavi Ltd | Wholesale & retail | 2023 |
| Ashvath Waterdales Ltd | Wholesale & retail | 2022 |
| Asisa Limited | Health & social care | 2023 |
| ASK Payroll Limited | Professional & scientific | 2019 |
| Askumez Securities and Services Ltd | Administrative & support | 2025 |
| ASL Machinery Limited | Wholesale & retail | 2016 |
| Aslamtex Ltd | Wholesale & retail | 2024 |
| Asom Construction Limited | Construction | 2023 |
| Asomrkt Ltd | Professional & scientific | 2024 |
| Aspiration Accountancy Services Ltd | Professional & scientific | 2011 |
| Aspiration HR Ltd | Administrative & support | 2024 |
| Aspiration IT Ltd | Information & communication | 2023 |
| Aspiration Services Ltd | Extraterritorial | 2024 |
| Aspirations Small Business Unit Limited | Professional & scientific | 2015 |
| Aspro Services Ltd | Administrative & support | 2023 |
| Asrj Capital Ltd | Real estate | 2024 |
| Assag Care Limited | Health & social care | 2019 |
| Assl Services Ltd | Construction | 2018 |
| Association for Person Centred Creative Arts Ltd. | Administrative & support | 2020 |
| Assurance Circle Limited | Information & communication | 2026 |
| Assured Capital Group Ltd | Construction | 2012 |
| Asteven Energy Academy UK Ltd | Education | 2022 |
| Astley Court Management Limited | Households | 1988 |
| Astonishing Travel & Tourism Limited | Administrative & support | 2023 |
| Astra IT Technologies Limited | Information & communication | 2025 |
| Astute Aesthetics Limited | Other services | 2015 |
| Astute Management Limited | Professional & scientific | 2024 |
| ASV South East Ltd | Wholesale & retail | 2024 |