| Archer Partnership Limited | Administrative & support | 2017 |
| Arches Close Management Company Ltd | Real estate | 2013 |
| Archie Lovatt Racing Limited | Arts & recreation | 2020 |
| Archisurv (UK) Limited | Professional & scientific | 2014 |
| Architance Ltd | Information & communication | 2018 |
| Architecture First Ltd | Extraterritorial | 2019 |
| Archway House (Duffield) Management Company Limited | Real estate | 2008 |
| Archway Motors of Findern Limited | Professional & scientific | 1957 |
| Arcp Residential Ltd | Real estate | 2024 |
| Arctic Cabins Trustee Limited | Professional & scientific | 2022 |
| Arctic Gold Limited | Agriculture & fishing | 2010 |
| Arcus Helicopters Limited | Transport & logistics | 2017 |
| Arden Laker Limited | Professional & scientific | 2016 |
| Arden Park Investments Limited | Financial services | 2017 |
| Ardenix Systems Ltd | Information & communication | 2012 |
| Arderwell (Lichfield Road) Limited | Real estate | 2026 |
| Arderwell (Park Street) Limited | Real estate | 2026 |
| Arderwell Property Limited | Financial services | 2026 |
| Ardonald Renewables Limited | Energy | 2024 |
| Ardsley Management Company Limited | Households | 1998 |
| ARE Construction Limited | Construction | 2018 |
| Areeco Limited | Wholesale & retail | 2025 |
| Arego Kawere Limited | Health & social care | 2025 |
| Arenaxess Ltd | Manufacturing | 2020 |
| Arepita Ltd | Hospitality | 2024 |
| Aresre Capital Ltd | Real estate | 2024 |
| Arete Women CIC | Health & social care | 2026 |
| Aretii Ltd | Construction | 2025 |
| Argyle Housing Ltd | Real estate | 2026 |
| Arha Labs Limited | Information & communication | 2017 |
| ARI Bladez Limited | Other services | 2022 |
| Aria Court 1963 Limited | Extraterritorial | 2014 |
| Aricens Ltd | Information & communication | 2025 |
| Arietem Limited | Professional & scientific | 2016 |
| Arimiru Limited | Wholesale & retail | 2018 |
| Arimiru Trans Ltd | Transport & logistics | 2014 |
| Aris Meraki Limited | Health & social care | 2025 |
| Aristotle Financial Planning Ltd | Financial services | 2017 |
| Ariya | Arts & recreation | 2009 |
| ARJ Stores Ltd | Wholesale & retail | 2024 |
| Arjan Properties (Derby) Ltd | Real estate | 2019 |
| Arjc Ltd | Hospitality | 2024 |
| ARK Builders (Derby) Limited | Construction | 2022 |
| ARK Building Solutions Ltd | Construction | 2024 |
| ARK Capital Investments Limited | Financial services | 2017 |
| ARK Childcare (UK) Limited | Education | 2005 |
| ARK Developments (Derby) Ltd | Construction | 2023 |
| ARK Fine Art Limited | Arts & recreation | 2024 |
| ARK Housing Ltd | Real estate | 2025 |
| Arksun Properties Ltd | Real estate | 2022 |
| Arkwright Concept Design Ltd. | Professional & scientific | 2020 |
| Arkwright Motors Ltd | Wholesale & retail | 2025 |
| Arlesey Residents Management Company Limited | Households | 2025 |
| Arleston Bookings Limited | Hospitality | 2024 |
| Arlt Group Ltd | Administrative & support | 2025 |
| Arlt Lifestyle Group Ltd | Arts & recreation | 2025 |
| ARM Furniture Limited | Wholesale & retail | 2013 |
| ARM Furniture Network Limited | Wholesale & retail | 2017 |
| Arman Ltd | Hospitality | 2018 |
| Armando Property Ltd | Real estate | 2023 |
| Armonia Properties Limited | Real estate | 2023 |
| Armsgate (Melbourne) Management Company Limited | Households | 2018 |
| Armson & Partners Ltd. | Professional & scientific | 2000 |
| Armstrong One Limited | Administrative & support | 2023 |
| ARN Trade Limited | Hospitality | 2011 |
| Arnage Base Ltd | Transport & logistics | 2023 |
| Arnold Street Projects Ltd | Real estate | 2020 |
| Arnot Investments Ltd | Real estate | 2025 |
| ARO Courier Service Ltd | Transport & logistics | 2018 |
| ARO Barber Ltd | Other services | 2022 |
| Aroma by Meas Limited | Wholesale & retail | 2025 |
| Aromoss Limited | Manufacturing | 2014 |
| Arora Sons Properties Limited | Real estate | 2021 |
| Around Noon (Bakery) Limited | Manufacturing | 2016 |
| ARP Sports Consultancy Ltd | Professional & scientific | 2026 |
| Arquis Homes Ltd | Real estate | 2021 |
| Arran Topham Ltd | Arts & recreation | 2012 |
| Array Technologies UK Limited | Manufacturing | 2021 |
| Arrivo Residence Ltd | Real estate | 2025 |
| Arrove Holdings Limited | Real estate | 2022 |
| Arrove Limited | Real estate | 1977 |
| Arrow Lift Trucks Limited | Manufacturing | 1987 |
| Arrow Utility Consulting Limited | Professional & scientific | 2006 |
| Arrowsmith Group Limited | Other services | 2024 |
| Arrv Limited | Construction | 2026 |
| Arsenia Ltd | Other services | 2020 |
| Art Consultancy Group Ltd | Professional & scientific | 2023 |
| Art Engineering Limited | Manufacturing | 2025 |
| Art Finance Group Limited | Professional & scientific | 2024 |
| Art of Mortgage Co Ltd | Financial services | 2025 |
| Art Stone Engraving Ltd | Other services | 2017 |
| Art Stone Memorials Ltd | Other services | 2016 |
| Art TEK Homz Ltd | Hospitality | 2022 |
| Artcore Limited | Arts & recreation | 2012 |
| Artec Property Limited | Real estate | 2022 |
| Artemis PM Ltd | Other services | 2023 |
| Artha Estates Limited | Real estate | 2024 |
| Arthritis Foodie Limited | Professional & scientific | 2022 |
| Arthur Holmes and Sons Limited | | 1924 |
| Arthur Rose Developments Ltd | Real estate | 2021 |