| ARK Noon Limited | Administrative & support | 2010 |
| Arkarius Bidco Limited | Professional & scientific | 2016 |
| Arkarius Midco Limited | Professional & scientific | 2016 |
| Arkayem Limited | Wholesale & retail | 2021 |
| Arkham Solutions Limited | Administrative & support | 2014 |
| Arkton Engineering (Northern) Ltd. | Construction | 1997 |
| Arkvane Limited | Wholesale & retail | 2025 |
| ARL Network Solutions Ltd | Information & communication | 2021 |
| Arleoss Ltd | Transport & logistics | 2023 |
| Arleys Angels Commercial Limited | Administrative & support | 2014 |
| Arlo Property Group Ltd | Real estate | 2021 |
| Arlo's Play Café Ltd | Arts & recreation | 2025 |
| ARM Guard Ltd | Information & communication | 2019 |
| ARM Secure Holdings Limited | Financial services | 2015 |
| ARM Secure Ltd | Administrative & support | 2001 |
| ARM Secure Technology Ltd | Administrative & support | 2018 |
| Armacy Ltd | Professional & scientific | 2021 |
| Armada Livings Limited | Hospitality | 2023 |
| Armando Project Services Ltd | Professional & scientific | 2019 |
| Armetis Limited | Administrative & support | 2013 |
| Armitstead Training Ltd | Information & communication | 2022 |
| Armstrong (Glazebury) Ltd | Construction | 2006 |
| Armstrong Commissioning Services Limited | Professional & scientific | 2019 |
| Armstrong Homes Ltd | Real estate | 2025 |
| Armstrong Management Ltd | Real estate | 2020 |
| ARN Interiors Ltd | Construction | 2015 |
| Arne CLO Ltd | Wholesale & retail | 2018 |
| Arne CLO Retail Ltd | Wholesale & retail | 2024 |
| Aron Side Ltd | Construction | 2022 |
| Arora Materials Limited | Wholesale & retail | 2025 |
| Aroratech Consulting Limited | Administrative & support | 2025 |
| Aros Butchers Ltd | Wholesale & retail | 2025 |
| Aros Kitchen Warrington Ltd | Hospitality | 2024 |
| Arosio Consultancy Ltd | Professional & scientific | 2024 |
| Around & Kind Ltd | Wholesale & retail | 2026 |
| ARP Plan Services Limited | Professional & scientific | 2022 |
| Arqore Ltd | Information & communication | 2025 |
| ARR CSA Limited | Administrative & support | 2014 |
| Arratech Solutions Ltd | Information & communication | 2019 |
| Arrival Star Transport Ltd | Transport & logistics | 2021 |
| Arrivals Star Limited | Transport & logistics | 2012 |
| Arrow Group 360 Ltd | Construction | 2021 |
| Arrow Logistics Solutions Ltd | Transport & logistics | 2025 |
| Arrow Taxis and Airport Transfers Ltd | Transport & logistics | 2025 |
| Arstek Ltd | Wholesale & retail | 2023 |
| Art Express (Leigh) Limited | Transport & logistics | 2007 |
| Art of Glass Ltd | Arts & recreation | 2024 |
| Artemis Electrical Consultancy Limited | Professional & scientific | 2019 |
| Arterior Developments Limited | Construction | 2017 |
| Arterior Limited | Financial services | 2015 |
| Arterior Solutions Ltd | Construction | 2011 |
| Artery Limited | Professional & scientific | 2018 |
| Artgirlrising UK Ltd | Manufacturing | 2020 |
| Arthog Property Company Limited | Real estate | 2016 |
| Arthur Elkin(Skirts)Limited | Manufacturing | 1956 |
| Arthur Engineering Services Limited | Professional & scientific | 2018 |
| Arthur William Law Limited | Professional & scientific | 2026 |
| Artificial Grass Warrington Ltd | Administrative & support | 2020 |
| Artisan Deco Ltd | Manufacturing | 2024 |
| Artisan Market Group Limited | Wholesale & retail | 2026 |
| Artpoltruck Ltd | Transport & logistics | 2022 |
| Artsan Coffee Ltd | Hospitality | 2024 |
| Arty Events Limited | Arts & recreation | 2025 |
| ARU Investments Limited | Financial services | 2019 |
| Arundel Consulting Ltd | Professional & scientific | 2025 |
| ARV Engineering Limited | Professional & scientific | 2016 |
| ARW Traffic Consultancy Limited | Transport & logistics | 2022 |
| Arya NW Ltd | Financial services | 2024 |
| Aryahi Limited | Health & social care | 2020 |
| Aryndan Health & Care Limited | Manufacturing | 2013 |
| Aryndan Housing Ltd | Real estate | 2025 |
| Arzu and Saifur and Shahi Limited | Hospitality | 2025 |
| AS Design Solutions Limited | Professional & scientific | 2017 |
| AS Industrial Doors Limited | Manufacturing | 2025 |
| AS Kitchens Limited | Construction | 2007 |
| AS Limitless Ltd | Professional & scientific | 2021 |
| AS Plumbing Contractors Limited | Construction | 2024 |
| AS1 Business Solutions Limited | Administrative & support | 2022 |
| ASA Aviation Consulting Limited | Administrative & support | 2014 |
| Asaao Ltd | Information & communication | 2023 |
| Asabrs Ltd | Manufacturing | 2024 |
| Asavari Consulting Limited | Administrative & support | 2012 |
| ASB Construction Services Limited | Administrative & support | 2025 |
| Asbestos Management and Consultancy Ltd | Education | 2018 |
| Ascend Project Solutions Limited | Other services | 2016 |
| Ascendant IT Limited | Administrative & support | 2013 |
| Ascendo Recruitment Ltd | Administrative & support | 2023 |
| Ascension Risk Management Limited | Administrative & support | 2025 |
| Ascot Bridging Finance 2 Limited | Financial services | 2019 |
| Ascot Bridging Finance 3 Limited | Financial services | 2021 |
| Ascot Bridging Finance 4 Limited | Financial services | 2022 |
| Ascot Bridging Finance Limited | Financial services | 2011 |
| Ascot Estates Limited | Real estate | 2014 |
| Ascot Integrated Engineering Ltd | Administrative & support | 2025 |
| Ascot Mortgages Limited | Professional & scientific | 2008 |
| Ascs Digital Design Ltd | Professional & scientific | 2018 |
| ASE Engineering Limited | Professional & scientific | 2016 |
| ASE Property Solutions Ltd | Construction | 2018 |
| Asecco Consulting Limited | Administrative & support | 2026 |
| Asela Limited | Health & social care | 2022 |