| Aria Alba - Opera for ALL | Edinburgh | 2011 |
| Aria Art and Movement Community Interest Company | Sunderland | 2021 |
| Aria Art Ltd | Sheffield | 2021 |
| Aria Design Studios Ltd | Hampton | 2025 |
| Aria Entertainment Concerts Ltd | London | 2014 |
| Aria Entertainment Ltd | London | 2011 |
| Aria Records Limited | London | 2020 |
| Aria Shows Ltd | London | 2024 |
| Arialtrail Ltd | Scunthorpe | 2015 |
| Ariamathea Ltd | Newton Abbot | 2016 |
| Ariana Menassa Ltd | Leatherhead | 2025 |
| Arianne Piper Art Advisory Limited | London | 2006 |
| Ariastec Ltd | Leeds | 2023 |
| Ariel Community Theatre CIC | Bolney | 2018 |
| Ariel Company Theatre Limited | Bolney | 2006 |
| Aries Entertainment Ltd | Birmingham | 2008 |
| Aries VIP Limited | Weston-Super-Mare | 2020 |
| Arif and Ricky Ltd | Droitwich | 2023 |
| Arif Rashid Cricket Coaching Ltd | Mitcham | 2020 |
| Arika Heavy Industries CIC | Edinburgh | 2006 |
| Arion Polo Ltd | Shinfield | 2017 |
| Aris Group Limited | Stevenage | 2025 |
| Arisaig Adventure Ltd | Milnthorpe | 2015 |
| Arise Talent Limited | Ascot | 2025 |
| Aristo Films Limited | Hertfordshire | 1973 |
| Aristocrat Technologies Europe (Holdings) Limited | London | 1997 |
| Aristoren Filmworks Ltd | Waltham Cross | 2017 |
| Aristos Fitness Ltd | Stewarton | 2014 |
| Ariwa Ltd | London | 2019 |
| Ariya | Derby | 2009 |
| Ariya Arts Ltd | Droitwich | 2020 |
| Arizent Limited | Suffolk | 2007 |
| Arjram Investments Ltd | Harrow | 2023 |
| Arjun Jacks Tattoo Limited | Harrow | 2025 |
| Arjuna Fine Arts Studio London Limited | Enfield | 2024 |
| Arjw Events Ltd | Newcastle Upon Tyne | 2026 |
| ARK Agency Network Ltd | Birmingham | 2025 |
| ARK Alive | Leeds | 2004 |
| ARK Fine Art Limited | Derby | 2024 |
| ARK Konditioning Ltd | Carlisle | 2026 |
| ARK Motorsport Ltd | Mountain Ash | 2024 |
| ARK Padel Limited | Preston | 2026 |
| ARK PR Limited | Worthing | 2012 |
| ARK Scenery Limited | Eye | 2024 |
| ARK Security Services Limited | Glasgow | 1988 |
| ARK Soccer Ltd | Heanor | 2019 |
| ARK Sport Ltd | Glasgow | 2015 |
| ARK Sports and Leisure Ltd | Burton-On-Trent | 2015 |
| ARK Sports Management Limited | Horsham | 2024 |
| ARK Studios Global Limited | Norwich | 2019 |
| ARK Three Limited | Leicester | 2015 |
| ARK4ART Ltd | London | 2014 |
| Arka Music Ltd | St. Leonards-On-Sea | 2024 |
| Arkan Performance Ltd | Sheffield | 2026 |
| Arkaneph Productions Ltd | London | 2023 |
| Arkartz Limited | Barcombe | 2025 |
| Arkatim Limited | Solihull | 2010 |
| Arke Optics Ltd | Woking | 2023 |
| Arke Wellness Ltd | Wetherby | 2025 |
| Arken Creative Limited | Stirling | 2020 |
| Arkeron Productions Limited | Chorley | 2019 |
| Arketype Limited | Rustington | 2006 |
| Arkhaus Limited | Broadstone | 1989 |
| Arkid Limited | Sheffield | 2023 |
| Arkid Media Limited | Bury | 2022 |
| Arkill Matthews Allen Limited | Rossett | 2008 |
| Arkleby Leisure Limited | Aspatria | 2003 |
| Arkley Fine Art Fairs Limited | Sandy | 2018 |
| Arlebury Parkland Limited | Alresford | 2015 |
| Arleen Wild Limited | Lincoln | 2005 |
| Arlen Smart Ltd | London | 2025 |
| Arlene Phillips Hot Gossip Limited | London | 1979 |
| Arlesey Leisure Ltd | Cambridge | 2018 |
| Arlesey Town Football Club Limited | Arlesey | 2014 |
| Arleta Berta Art Ltd | Knottingley | 2025 |
| Arlington Rural Community CIC | Barnstaple | 2023 |
| Arlo's Party Hire Limited | Brigg | 2019 |
| Arlo's Play Café Ltd | Warrington | 2025 |
| Arlos Castles and Softplay Ltd | Bedford | 2026 |
| Arlt Lifestyle Group Ltd | Derby | 2025 |
| ARM Boxing Limited | Liverpool | 2012 |
| ARM Padel Club Ltd | Hyde | 2025 |
| ARM Wars International Limited | Blackburn | 2015 |
| Arma Cine Ltd | Woking | 2023 |
| Arma Events Consulting Ltd | Worcester | 2016 |
| Armaan World Records Ltd | Willenhall | 2025 |
| Armada Music UK Limited | London | 2018 |
| Armadale Speedway Club Limited | Midlothian | 1999 |
| Armadillo Sports Design Limited | Macclesfield | 2000 |
| Armagh Fisheries Limited | Armagh | 1962 |
| Armagh Fitness Works Limited | Armagh | 2016 |
| Armagh Pipers Club | Armagh | 2013 |
| Armagh Theatre Company Limited | Armagh | 1998 |
| Armalyte Industries Ltd | Epsom | 2013 |
| Armand International Limited | Altrincham | 2000 |
| Armandj Ltd | Airdrie | 2021 |
| Armbrella Ltd | Milton Keynes | 2025 |
| Armchair Theatre Ltd | Southampton | 2012 |
| Armed Forces Para-Snowsport Team | London | 2011 |
| Armitage Bridge Cricket Club (Community) Ltd | Huddersfield | 2024 |