| Arabella's Baby Boutique Ltd | Wholesale & retail | 2017 |
| Arami Essentials Limited | Wholesale & retail | 2020 |
| Araniraj Ltd | Administrative & support | 2026 |
| Arav Fashion Services UK Ltd | Professional & scientific | 2023 |
| ARB Media Ltd | Professional & scientific | 2024 |
| Arbaa Blue Limited | Real estate | 2025 |
| Arbii Demolition Ltd | Construction | 2008 |
| Arboak Ltd | Professional & scientific | 2025 |
| ARC Identity Ltd | Wholesale & retail | 2026 |
| ARC Property Collective Ltd | Real estate | 2026 |
| ARC Solutions (South) Ltd | Construction | 2023 |
| Arcade Hair Salon Ltd | Other services | 2020 |
| Arcade International Limited | Wholesale & retail | 2003 |
| Arcane Events Ltd | Administrative & support | 2026 |
| Arcetype Ltd | Wholesale & retail | 2024 |
| Arch Education Limited | Education | 2015 |
| Archangel (UK) Limited | Other services | 2002 |
| Archangel Corporation Limited | Other services | 2010 |
| Archangel Group Limited | Extraterritorial | 2024 |
| Archangel Holdings Limited | Extraterritorial | 2021 |
| Archangel Properties ( UK ) Limited | Real estate | 2016 |
| Archel Limited | Construction | 2025 |
| Archer Property Care Ltd | Real estate | 2026 |
| Archers Park 1 Limited | Households | 2014 |
| Archesboxing Limited | Arts & recreation | 2012 |
| Archies Motor Club Ltd | Administrative & support | 2022 |
| Archilibrium Limited | Professional & scientific | 2014 |
| Archmont Limited | Households | 1973 |
| Archway (T C S) Limited | Manufacturing | 2001 |
| Archway Corner Limited | Households | 2025 |
| Arcon Village Management Company Limited | Households | 2004 |
| Arcura (Holdings) Limited | Financial services | 2017 |
| Arcura Limited | Construction | 2017 |
| Ardd Limited | Real estate | 2026 |
| Ardeka UK Limited | Wholesale & retail | 2024 |
| Ardensuk Ltd | Construction | 2016 |
| Ardin Limited | Real estate | 1988 |
| Ardour & Moore Construction Ltd | Construction | 2023 |
| Ardouscorp Ltd | Information & communication | 2025 |
| Ardra and Athira Properties Ltd | Real estate | 2025 |
| Ardwick Field Management Company Limited | Households | 2009 |
| Arenika Ltd | Real estate | 2022 |
| Areretta's Limited | Manufacturing | 2017 |
| Aresponse Plumbing and Heating Limited | Construction | 2004 |
| Arete Domus Limited | Real estate | 2023 |
| Areya IT Services Limited | Information & communication | 2016 |
| Arfurla Limited | Wholesale & retail | 2023 |
| Argento Catering Ltd | Hospitality | 2019 |
| Argoed Gardens Management Limited | Households | 2018 |
| Arhi Trading Ltd | Wholesale & retail | 2017 |
| Ariano Consulting Limited | Professional & scientific | 2025 |
| Aries & Associates Limited | Construction | 2013 |
| Aries Global Limited | Professional & scientific | 2026 |
| Arifem Ltd | Hospitality | 2023 |
| Arimax | Administrative & support | 2013 |
| Aris Design & Management Ltd | Other services | 2007 |
| Arise Fellowship Christian Church CIC | Other services | 2023 |
| Arising Cleaning Services Ltd | Administrative & support | 2019 |
| Arissa Investments Limited | Real estate | 2025 |
| ARK Engineer Pro Limited | Professional & scientific | 2024 |
| ARK Group International Ltd | Professional & scientific | 2021 |
| ARK Independent Solutions Limited | Financial services | 2019 |
| ARK UK Integrated Services Ltd | Other services | 2021 |
| Arkley Farm Limited | Administrative & support | 1992 |
| Arlahall Limited | Construction | 2001 |
| Arlington Road Healthcare LLP | | 2012 |
| ARM Vencap Ltd | Construction | 2019 |
| Arman Trans GBT Ltd | Transport & logistics | 2021 |
| Armin Goods and Services Ltd | Transport & logistics | 2023 |
| Armourtus Ltd | Construction | 2018 |
| ARN Construction Limited | Construction | 2025 |
| Arnold & Boimer Limited | Construction | 2022 |
| Arnos Customzz Ltd | Wholesale & retail | 2025 |
| Arnulfo Ltd | Wholesale & retail | 2017 |
| Aroma Box Ltd | Wholesale & retail | 2026 |
| Aroma Cafe (Southend) Ltd | Hospitality | 2022 |
| Arona House (Oakwood) Management Limited | Households | 2010 |
| Arondene Limited | Households | 2001 |
| Aroraveld Limited | Real estate | 2017 |
| Around LW Limited | Professional & scientific | 2014 |
| Arrabo Ltd | Wholesale & retail | 2025 |
| Arrahman Systems Limited | Information & communication | 2023 |
| Arrivata Plaza Management Company Limited | Real estate | 2009 |
| Arro Ventures Ltd | Professional & scientific | 2023 |
| Arrow Psychiatry Limited | Health & social care | 2024 |
| Arrowaden Limited | Households | 1985 |
| Arroxton Group Limited | Real estate | 2020 |
| Arroxton Solicitors Limited | Professional & scientific | 2022 |
| ARS Holding Group Limited | Administrative & support | 2021 |
| ARS Jewels Limited | Manufacturing | 2022 |
| ARS Private Hire Ltd | Transport & logistics | 2026 |
| ARS Trading Company Ltd | Administrative & support | 2021 |
| Arslan Fish Ltd | Hospitality | 2019 |
| Arston SI Ltd | Other services | 2015 |
| Art & Build Ltd | Construction | 2021 |
| Art Coffee Limited | Hospitality | 2024 |
| Art Lane Limited | Manufacturing | 2021 |
| Art NOW - Banstead Art School Ltd | Education | 2015 |
| Art Painting & Wallpaper Ltd | Construction | 2020 |
| Art Project 1 Ltd | Arts & recreation | 2018 |