| Armed Forces Financial Services Limited | Ashford | 2013 |
| Armertec Limited | Kettering | 2023 |
| Armfield Technical Education Company Limited | London | 1980 |
| Armi Marin Ltd | London | 2025 |
| Armiger Estates Limited | Ely | 2020 |
| Armintex Ltd | Portsmouth | 2023 |
| Armishaws Holdings Limited | Gillingham | 2014 |
| Armistead Holdings Limited | Penrith | 2019 |
| Armita Global Ltd | Birmingham | 2013 |
| Armitage (Funeral Directors) Limited | Sutton Coldfield | 1998 |
| Armitage Airsoft Ltd | Brackley | 2025 |
| Armitage and Rigby Limited | Uxbridge | 1953 |
| Armitage Coaching and Consulting Ltd | Whalley | 2019 |
| Armitage Communications Limited | Chichester | 2004 |
| Armitage Rest Homes Limited | Keighley | 1999 |
| Armitage Sykes Limited | Bradford | 2022 |
| Armitage Trustees Limited | Nottingham | 1999 |
| Armkandi Limited | Wednesfield | 2013 |
| Armon Group Ltd | London | 2025 |
| Armonia Wellness Ltd | Liverpool | 2022 |
| Armour Haulage Limited | Bath | 2013 |
| Armour Lift Limited | Stourbridge | 2022 |
| Armoury Limited | Ware | 2008 |
| Arms of an Angel Properties Ltd | Darlington | 2023 |
| Armstrong Aerial Access Limited | Blyth | 2014 |
| Armstrong Aviation Limited | Stockport | 2017 |
| Armstrong Burton Limited | Cirencester | 2008 |
| Armstrong Fluid Technology Limited | Manchester | 2013 |
| Armstrong Holden Brooke Pullen Limited | Manchester | 2010 |
| Armstrong Interiors (Northwest) Ltd | Heywood | 2011 |
| Armstrong Leisure Limited | Stockport | 2019 |
| Armstrong Massey (Driffield) Limited | Beverley | 2015 |
| Armstrong Rise 1959 Limited | Andover | 2014 |
| Armstrong Technology Associates Limited | London | 1994 |
| Armstrong Technology Ltd | Alderley Edge | 2011 |
| Armstrong Whitworth Aircraft Limited | Camberley | 1996 |
| ARMSTRONGB2B Limited | Chester | 2023 |
| Armstrongs Solicitors Limited | Liverpool | 2006 |
| Armworth House (UK) Limited | London | 2010 |
| ARN Group Ltd | London | 2016 |
| ARN London Ltd | London | 2016 |
| Arna Trans Ltd. | London | 2014 |
| Arncliffe Farms Limited | Northallerton | 2002 |
| Arnclyffe Limited | London | 2012 |
| Arndale House Liverpool RTM Company Limited | Leeds | 2021 |
| Arne Retail Ltd | Wareham | 2024 |
| Arnewood Motor Company Ltd | New Milton | 2013 |
| Arni Consultants Limited | Ilford | 2019 |
| Arnlap Limited | Preston | 1988 |
| Arno Agency Limited | London | 2018 |
| Arnoey Reklame & Design Ltd | London | 2007 |
| Arnold Clark Charge Limited | Glasgow | 2000 |
| Arnold Clark Energy Limited | Glasgow | 2024 |
| Arnold Clark Leasing Limited | Glasgow | 2024 |
| Arnold Clark Vehicle Management Limited | Glasgow | 2015 |
| Arnold Grant & Waters NO. 7 Limited | Chelmsford | 2021 |
| Arnold Property Solutions Ltd | Brentford | 2012 |
| Arnolds Holding Limited | London | 2023 |
| ARO Affinity Limited | Westerham | 2011 |
| ARO International Limited | Chiselhurst | 2004 |
| ARO Online Limited | Westerham | 2013 |
| ARO Risk Limited | Westerham | 2011 |
| ARO Transport Norway Limited | London | 2025 |
| ARO Wrigley Chemical Industry UK Limited | Beckenham | 2018 |
| Aroma Albrighton Ltd | West Bromwich | 2016 |
| Aroma Aura Limited | London | 2018 |
| Aroma Baby Limited | Reading | 1999 |
| Aroma Formulations Ltd | Hinckley | 2013 |
| Aromaa Commodities Ltd | Sutton Coldfield | 2025 |
| Aromacare Ltd | Fleet | 2013 |
| Aromark Limited | Reading | 2000 |
| Aromas Flavourtech UK Ltd | Manchester | 2020 |
| Aromatime Ltd | London | 2011 |
| Aron Corporation Ltd | London | 2025 |
| Aronmere Limited | London | 2020 |
| Arora Developments Ltd | Hounslow | 1999 |
| Arora Finance Limited | Hounslow | 2006 |
| Arora Heathrow Investments Limited | Hounslow | 2006 |
| Arora Manchester Limited | Hounslow | 2004 |
| Aros Trustee Limited | London | 2025 |
| Arot Holding Limited | London | 2019 |
| ARP Europe Limited | Bolton | 2004 |
| ARP Grantham 1 Ltd | Manchester | 2021 |
| ARP Grantham 2 Ltd | Manchester | 2021 |
| Arpadson Limited | London | 2023 |
| Arpita DE Ltd | Caerphilly | 2023 |
| Arran Wishes Ltd | Isle Of Arran | 2023 |
| Arrandco 2026 Limited | London | 2015 |
| Arrandene Driveway Limited | London | 2007 |
| Arrange My Group Ltd | Worcester | 2015 |
| Arranmore Ltd | Larne | 2018 |
| Arranz Ltd | London | 2022 |
| Arredamento Design Ltd | Stafford | 2022 |
| Arren James Hymas Limited | Truro | 2024 |
| Arriba Limited | Chipping Campden | 2025 |
| Arriba London Limited | London | 2017 |
| Arrigo Programme Ltd | Castle Cary | 2011 |
| Arriva Building Supplies Limited | Gloucester | 2015 |
| Arriva Care Limited | Gloucester | 2009 |
| Arriva Construction Limited | Gloucester | 2015 |