| Ariet Global Limited | Wholesale & retail | 2025 |
| Arigo Ltd | Transport & logistics | 2025 |
| Arinola Group Ltd | Hospitality | 2024 |
| Ariomaghwa Ladies Association UK Limited | Other services | 2015 |
| Arioms Limited | Wholesale & retail | 2026 |
| Arion Security (UK) Ltd | Administrative & support | 2010 |
| Ariq Capital Ltd | Wholesale & retail | 2025 |
| Arise Healthcare Ltd | Health & social care | 2025 |
| Arisen Services UK Ltd | Administrative & support | 2021 |
| Arish Global Services Ltd | Information & communication | 2019 |
| Arish Grab & Go Limited | Wholesale & retail | 2025 |
| Aristone Limited | Professional & scientific | 2018 |
| Arita Limited | Administrative & support | 2020 |
| Arithmagicians Ltd | Education | 2022 |
| Ariv Investments Limited | Real estate | 2018 |
| Ariyla Properties Limited | Real estate | 2025 |
| ARJ Property Consultants Ltd | Construction | 2023 |
| Arjun Trading Ltd | Wholesale & retail | 2022 |
| ARK Airport Transfer Ltd | Transport & logistics | 2024 |
| ARK Luton Ltd | Wholesale & retail | 2024 |
| ARK Svcs Limited | Administrative & support | 2026 |
| Arkan RAV Ltd | Other services | 2017 |
| Arkenstone Property Solutions Ltd | Construction | 2026 |
| Arketa Aesthetics Ltd | Professional & scientific | 2022 |
| Arkii Ltd | Information & communication | 2026 |
| Arla Ltd | Information & communication | 2026 |
| Arlesey Car & Commercials Limited | Wholesale & retail | 1984 |
| Arlicc Ltd | Wholesale & retail | 2026 |
| Armaan Sandhu Limited | Real estate | 2024 |
| Armagedon Ltd | Transport & logistics | 2025 |
| Arman Five Star Motors Limited | Transport & logistics | 2016 |
| Armeen Ltd | Wholesale & retail | 2025 |
| Armitage Management Consulting Ltd | Professional & scientific | 2020 |
| Armour Beast Ltd | Wholesale & retail | 2026 |
| Armour Building Maintenance Limited | Construction | 2020 |
| Armoured Drives Ltd | Construction | 2016 |
| Armstrong After Care Services Ltd | Public administration | 2021 |
| Armstrong Consultancy and Training Ltd | Professional & scientific | 2022 |
| Arnada Limited | Administrative & support | 2022 |
| Arndale Court Management Limited | Households | 1994 |
| ARO Logistics and Investment Ltd | Transport & logistics | 2026 |
| Arobi Holdings Ltd | Real estate | 2019 |
| Aroma 28 Limited | Hospitality | 2024 |
| Aromaticjoe Ltd | Wholesale & retail | 2017 |
| Aron Property Management UK Ltd | Real estate | 2019 |
| Aron Scaffolding Ltd | Construction | 2022 |
| Aron Tech Contracts Ltd | Information & communication | 2023 |
| Around YOU Support & Community Services Ltd | Health & social care | 2022 |
| Aroxas Ltd | Health & social care | 2022 |
| ARP Properties Limited | Construction | 2006 |
| Arpenviro Ltd | Professional & scientific | 2018 |
| ARRC44 Holdings Ltd | Arts & recreation | 2026 |
| Arrow Transport Ltd | Transport & logistics | 2010 |
| Arruda Forwarding UK Limited | Transport & logistics | 2017 |
| Arry Corp Ltd | Hospitality | 2014 |
| Arry Innovations Limited | Wholesale & retail | 2024 |
| ARS Properties MK Limited | Real estate | 2018 |
| Arsb Ltd | Financial services | 2023 |
| Arsh Logistics Limited | Transport & logistics | 2023 |
| Arshad & Sons Properties Limited | Real estate | 2021 |
| Arsons Limited | Wholesale & retail | 2025 |
| Art & EDY Ltd | Construction | 2015 |
| Art Building and Interiors Ltd | Construction | 2022 |
| Art of Jannah Limited | Manufacturing | 2006 |
| Art Sweets Limited | Manufacturing | 2023 |
| Art-Deco London Limited | Construction | 2015 |
| Artemis Consultancy Services Limited | Professional & scientific | 2023 |
| Artes Technology Co., Ltd | Wholesale & retail | 2022 |
| Arthur H.Stockwell,Limited | Information & communication | 1925 |
| Artisan Fusion Limited | Administrative & support | 2024 |
| Artj Electricals Ltd | Construction | 2025 |
| Arttru Ltd | Construction | 2015 |
| ARU Building Construction Limited | Construction | 2026 |
| Aruka Realtek Limited | Information & communication | 2023 |
| Arundel Properties (Luton) Ltd | Real estate | 2013 |
| Aruntransport Limited | Transport & logistics | 2016 |
| Arvent Estates Ltd | Real estate | 2022 |
| Arwa Contractors Ltd | Administrative & support | 2024 |
| ARX Vitae Ltd | Health & social care | 2025 |
| Arya Retail Limited | Wholesale & retail | 2025 |
| Aryan Builders Ltd | Construction | 2020 |
| Arye Attire Limited | Wholesale & retail | 2024 |
| AS BIO Packs Ltd | Real estate | 2019 |
| AS Car Dealers Ltd | Wholesale & retail | 2024 |
| AS Collab 2 Limited | Real estate | 2025 |
| AS Collab Ltd | Real estate | 2023 |
| AS Dream Limited | Hospitality | 2025 |
| AS Enterprises (GB) Limited | Wholesale & retail | 2008 |
| AS Grewal Ltd | Construction | 2024 |
| AS Luton Limited | Real estate | 2018 |
| AS Property Group Ltd | Real estate | 2022 |
| ASA Healthcare Ltd | Professional & scientific | 2023 |
| ASA Private Hire Limited | Transport & logistics | 2019 |
| Asaa Properties Ltd | Real estate | 2024 |
| Asad Nabiha Ltd | Financial services | 2025 |
| Asad Transport Limited | Transport & logistics | 2025 |
| Asads Tradeland Ltd | Wholesale & retail | 2024 |
| Asaf Construction Ltd | Construction | 2026 |
| Asamad Ltd | Wholesale & retail | 2026 |
| Asamto Ltd | Transport & logistics | 2025 |