| Appnable Limited | Information & communication | 2014 |
| Apps Unlimited Ltd | Information & communication | 2017 |
| Appsync Designs Ltd | Information & communication | 2025 |
| Apricot Virtual Support Limited | Information & communication | 2005 |
| Aprilis Support Care Limited | Health & social care | 2022 |
| APS Screeding Limited | Construction | 2015 |
| APT Care (Bedford) Limited | Health & social care | 2014 |
| APT Care Limited | Health & social care | 2006 |
| APT Direct Limited | Wholesale & retail | 2026 |
| Aptus Financial Ltd | Financial services | 2015 |
| AQ Group Ltd | Professional & scientific | 2025 |
| AQB Management Consulting Ltd | Other services | 2020 |
| Aqinterflow Ltd | Other services | 2024 |
| Aqofficial Limited | Arts & recreation | 2022 |
| Aqtive Recovery 24/7 Ltd | Transport & logistics | 2023 |
| Aqua Dynamics Limited | Manufacturing | 2007 |
| Aqua JET Cleaning Ltd | Administrative & support | 2019 |
| Aquachemix Limited | Administrative & support | 1969 |
| Aquacloudsolutions Ltd | Information & communication | 2020 |
| Aquafizz Limited | Wholesale & retail | 2019 |
| Aquora Global Ltd | Wholesale & retail | 2018 |
| AR 17 Ltd | Wholesale & retail | 2025 |
| AR Auto Repairs Ltd | Wholesale & retail | 2026 |
| AR Dove Ltd | Hospitality | 2020 |
| AR Estates and Investments Limited | Real estate | 2023 |
| AR European Supermarket and OFF License Ltd | Wholesale & retail | 2022 |
| AR Events Management Ltd | Hospitality | 2025 |
| AR FMM Ltd. | Information & communication | 2022 |
| AR Hire Group Limited | Administrative & support | 2026 |
| AR Legacy Holdings UK Ltd | Wholesale & retail | 2026 |
| AR Motor Services Ltd | Administrative & support | 2021 |
| AR Powertech Solutions Ltd | Construction | 2025 |
| AR Property Developer Ltd | Real estate | 2020 |
| AR Surveying and Consultancy Limited | Professional & scientific | 2023 |
| AR Therapy Ltd | Health & social care | 2019 |
| ARA UK Traders Ltd | Wholesale & retail | 2026 |
| ARA Varieties Global Limited | Wholesale & retail | 2026 |
| Arabian Parfums Ltd | Wholesale & retail | 2024 |
| Arachne Aero Ltd | Professional & scientific | 2020 |
| Araein Accounting Services Ltd | Information & communication | 2019 |
| Arain Holdings Limited | Real estate | 2017 |
| Aral Solutions Limited | Information & communication | 2006 |
| Aralarna (Basildon) Ltd | Construction | 2023 |
| Aralarna Limited | Real estate | 2022 |
| Aralb Electrical Ltd | Construction | 2018 |
| Arba Solutions Ltd | Construction | 2023 |
| Arban Emporium Ltd | Wholesale & retail | 2024 |
| Arbannest Ltd | Wholesale & retail | 2026 |
| Arbree Limited | Information & communication | 2016 |
| ARC Light Property Ltd | Construction | 2025 |
| Arcade Technologies Limited | Wholesale & retail | 2026 |
| Arcadia Casino Limited | Arts & recreation | 2020 |
| Arcas Services Ltd | Construction | 2022 |
| Archaea Mass Limited | Arts & recreation | 2000 |
| Archbishop Porter Past Students' Association Midlands | Education | 2024 |
| Archer Shield Services Ltd | Administrative & support | 2025 |
| Archetek Industries Ltd | Information & communication | 2025 |
| Archewell Logistics Limited | Transport & logistics | 2021 |
| Archewell Management Ltd | Professional & scientific | 2021 |
| Archincad Ltd. | Professional & scientific | 2013 |
| ARCHIT3CH Ltd | Information & communication | 2025 |
| Archive & Document Scanning Limited | Administrative & support | 2009 |
| Archstone Estates Ltd | Real estate | 2023 |
| Archway Blue Limited | Professional & scientific | 2020 |
| Arcshore Limited | Information & communication | 2026 |
| ARD Reinforcement Construction Ltd | Construction | 2024 |
| Ard-Ln Cars Ltd | Transport & logistics | 2025 |
| Ardara Construction Services Limited | Construction | 2005 |
| Ardayedu Ltd | Education | 2024 |
| Ardbury Ltd | Construction | 2020 |
| Ardeconstruct Ltd | Construction | 2025 |
| Ardent Solutions Ltd | Professional & scientific | 2024 |
| Ardentisys Limited | Information & communication | 2008 |
| Area Boys Barbers Limited | Other services | 2020 |
| Areas .Corp Limited | Professional & scientific | 2015 |
| Areaverta Technologies Logistics & Facilities Management Ltd | Transport & logistics | 2025 |
| Aredpen Ltd | Information & communication | 2025 |
| Areeshah Wedding Services Ltd | Hospitality | 2011 |
| Ares Plates Ltd | Manufacturing | 2025 |
| Ares Systems Ltd | Manufacturing | 2025 |
| Arewa Consultants Ltd | Professional & scientific | 2020 |
| Arfama Properties Limited | Administrative & support | 2017 |
| Arfiri Investments Ltd | Real estate | 2019 |
| Argan Motors Ltd | Information & communication | 2021 |
| Argan Vanity Ltd | Wholesale & retail | 2014 |
| Argcare Limited | Health & social care | 2019 |
| Argen Trans Ltd | Transport & logistics | 2023 |
| Argent Classics Limited | Transport & logistics | 2020 |
| Argento Global Solutions Ltd | Wholesale & retail | 2019 |
| Argimar Trans Ltd | Transport & logistics | 2018 |
| Argon Electronics (UK) Ltd | Manufacturing | 2010 |
| Arhotech Consulting Limited | Professional & scientific | 2016 |
| ARI Barber's 2023 Ltd | Other services | 2023 |
| ARI Events Ltd | Information & communication | 2021 |
| Ari&Zak Ltd | Information & communication | 2025 |
| Aria 8 Investments Ltd | Real estate | 2019 |
| Aria 8 Limited | Professional & scientific | 2016 |
| Aria Construction Group Ltd | Construction | 2023 |
| Aria Cycle Co Ltd | Wholesale & retail | 2024 |
| Arian Express Limited | Transport & logistics | 2021 |