| Archer's Construction Ltd | Construction | 2018 |
| Archer-Quiver Ltd | Information & communication | 2020 |
| Archers Environmental Solutions Ltd | Water & waste | 2025 |
| Archers Estate Agents Limited | Real estate | 2005 |
| Archers Glazing Ltd | Construction | 2023 |
| Archers Houses Ltd | Real estate | 2023 |
| Archform Byte Limited | Administrative & support | 2010 |
| Archipelago Arts Collective Ltd | Arts & recreation | 2019 |
| Architechnik Limited | Professional & scientific | 2010 |
| Architectural Design and Advice Limited | Professional & scientific | 2024 |
| Architectural Drawings Limited | Professional & scientific | 2003 |
| Architectural Improvement Ltd | Professional & scientific | 2016 |
| Architectural Innovation Limited | Construction | 2006 |
| Architectural Metalwork Installations Limited | Manufacturing | 2007 |
| Archive Matter Limited | Information & communication | 2021 |
| Archrace Limited | Transport & logistics | 1996 |
| Archway Building Company Limited | Construction | 1999 |
| Arcis Automation Ltd | Professional & scientific | 2026 |
| Arcl Associates Ltd | Health & social care | 2024 |
| Arco Kiniun Limited | Energy | 2021 |
| ARCO1 Ltd | Manufacturing | 2020 |
| Arcs Plastering Ltd | Construction | 2015 |
| Arctic Dispense Ltd | Manufacturing | 2016 |
| Arcturus Pillarstone Holdings Group Ltd | Health & social care | 2026 |
| Ardaa House Ltd | Hospitality | 2025 |
| Ardack Property Ltd | Real estate | 2022 |
| Ardak Company Ltd | Professional & scientific | 2024 |
| Ardent Developments Ltd | Construction | 2010 |
| Ardern Properties Limited | Real estate | 1999 |
| Arderne Property Group Ltd | Real estate | 2026 |
| Ardeta Search Limited | Administrative & support | 2022 |
| Ardiente Food Ltd | Hospitality | 2020 |
| Ardithysa Ltd | Transport & logistics | 2026 |
| Area Housing Limited | Real estate | 2022 |
| Areana Hand Car Wash Limited | Administrative & support | 2021 |
| Areeba Khushik Ltd | Health & social care | 2023 |
| Arelet Ltd | Real estate | 2007 |
| Arena Properties Limited | Real estate | 2019 |
| Arena Property Solutions Limited | Real estate | 2015 |
| Arenarenovation Ltd | Construction | 2022 |
| Ares Landscape Architects Limited | Professional & scientific | 2013 |
| Arete 69 Holdings Limited | Financial services | 2024 |
| Arete Consulting & Implementation Services Ltd | Professional & scientific | 2024 |
| Arete Kitchens UK Limited | Wholesale & retail | 2026 |
| Areumskin Limited | Wholesale & retail | 2025 |
| Arfiz Global Ltd | Wholesale & retail | 2025 |
| ARG Cars Ltd | Wholesale & retail | 2025 |
| ARG Property Ltd | Construction | 2024 |
| Argaus Limited | Health & social care | 2024 |
| Argent Steel Limited | Manufacturing | 1983 |
| Argentina Potassium Limited | Financial services | 2024 |
| Argo Feeds Limited | Wholesale & retail | 1956 |
| Argo Haulage (Penistone) Limited | Transport & logistics | 1976 |
| Argyll Ruane Limited | Education | 1985 |
| ARH Management Services Limited | Real estate | 2006 |
| Arhby Professionals Ltd | Health & social care | 2026 |
| Arho-Hpd Properties Limited | Financial services | 2018 |
| Ari's Spices Limited | Hospitality | 2025 |
| Aria Art Ltd | Arts & recreation | 2021 |
| Aria Events Group Ltd | Administrative & support | 2026 |
| Arialive Media Limited | Information & communication | 2025 |
| Arianna Tanko Ltd. | Hospitality | 2018 |
| Ariel Healthcare Ltd | Health & social care | 2017 |
| Arieni Ltd | Real estate | 2020 |
| Aries Enabling Limited | Construction | 2025 |
| Aries Property Ltd | Real estate | 2003 |
| Ariesmark Global Logistics Ltd | Wholesale & retail | 2019 |
| Arina Minimarket S2 Limited | Wholesale & retail | 2025 |
| Arini Technologies Ltd | Information & communication | 2021 |
| Arise Properties Ltd | Real estate | 2022 |
| Arish a 2 Z Ltd | Transport & logistics | 2020 |
| Arisha Limited | Health & social care | 2013 |
| Arista Investments Ltd | Real estate | 2024 |
| Aristotle Partnerships Limited | Financial services | 2019 |
| Ariyaththai Thamizh Palli CIC | Education | 2025 |
| ARJ Design Ltd | Professional & scientific | 2019 |
| ARJCONSTRUCTION22 Ltd | Construction | 2022 |
| ARK Cleaning and Linen Services LLP | | 2024 |
| ARK Design Management Limited | Professional & scientific | 1998 |
| ARK Estates Management LLP | | 2024 |
| ARK Infosoft Limited | Information & communication | 2025 |
| ARK Joinery & Timber Framing Limited | Construction | 2019 |
| ARK Service Holdings Ltd | Financial services | 2023 |
| ARK Serviced Accommodation Ltd | Hospitality | 2020 |
| ARK Short Stays Management Ltd | Hospitality | 2022 |
| ARK Talent Limited | Professional & scientific | 2019 |
| Arkan Football Ltd | Education | 2024 |
| Arkan Performance Ltd | Arts & recreation | 2026 |
| Arkelen Consulting Ltd | Information & communication | 1998 |
| Arkez Ltd | Hospitality | 2024 |
| Arkid Limited | Arts & recreation | 2023 |
| Arkle Investments Ltd | Financial services | 2023 |
| Arkom Limited | Information & communication | 1999 |
| Arkote Limited | Manufacturing | 2002 |
| ARL Traders Limited | Wholesale & retail | 2024 |
| Arley Street Space Ltd | Real estate | 2021 |
| Arlo Catering Ltd | Hospitality | 2026 |
| Armaj Property Limited | Real estate | 2025 |
| Armale Properties Ltd | Real estate | 2018 |
| Armitage Haulage Ltd | Transport & logistics | 2015 |