| Aiken Promotions | | 1961 |
| Ailbhe & Axel Ltd | Uxbridge | 2020 |
| Ailpt Fitness Ltd | Coventry | 2011 |
| Ailsa Craig Investments Ltd | Glasgow | 2024 |
| Ailsa MAY Dance Limited | Portree | 2022 |
| AIM (UK) Limited | London | 2012 |
| AIM Boxing & Fitness Ltd | Brighouse | 2025 |
| AIM Entertainments Limited | Holborn | 2012 |
| AIM Equestrian Limited | Glasgow | 2023 |
| AIM for the Sky Ltd | Neston | 2012 |
| AIM Foundation | London | 2016 |
| AIM High Cheshire Ltd | Altrincham | 2024 |
| AIM High Rugby Coaching Limited | Pont-Y-Clun | 2024 |
| AIM Lifestyle Ltd | Liverpool | 2026 |
| AIM Performance Ltd | Cradley Heath | 2019 |
| AIM Play Ltd | Sutton | 2019 |
| AIM Sports Academy Limited | Bridgend | 2016 |
| AIM Sports Group Ltd | Ashbourne | 2025 |
| AIM Studio Ltd | Newcastle Upon Tyne | 2023 |
| AIM to FLY UK Ltd | Swindon | 2026 |
| AIM Training South West Limited | Langport | 2015 |
| AIM Writing Limited | Redhill | 2016 |
| AIM2B Ltd | Leyland | 2024 |
| AIM4 Partnerships C.I.C. | Margate | 2011 |
| AIM4SPORT Limited | Sandy | 2006 |
| AIM4SPORT Training Centre Ltd | Sandy | 2014 |
| Aimco Limited | London | 2005 |
| Aimd Art Limited | Tonbridge | 2016 |
| Aimee Abigail Leigh and Associates Ltd | Preston | 2013 |
| Aimee Cringle Limited | Worcester | 2025 |
| Aimee Jane Dance Company Ltd | Maidstone | 2021 |
| Aimee Louise School of Dance Ltd | Tamworth | 2019 |
| Aimee Ormesher Limited | Liverpool | 2019 |
| Aimee Paton Ltd | London | 2025 |
| Aimee Sadler Fitness Limited | Great Dunmow | 2021 |
| Aimee Willmott Limited | Stockton-On-Tees | 2014 |
| Aimee-Leigh Irish Dance Academy Ltd | Chatham | 2022 |
| Aimfitwestlondon Limited | Gerrards Cross | 2022 |
| Aimie G Coaching Ltd | Bexley | 2025 |
| Aimless.Tech CIC | Jarrow | 2019 |
| Aimputt Limited | Trafford Park | 2021 |
| Aimzee Doodlez Ltd | Leicester | 2020 |
| Aine Rose Daly Limited | Sheffield | 2021 |
| Ainsdale Sports Ltd | Liverpool | 2013 |
| Ainsley Buchanan Limited | Redcar | 2024 |
| Ainsworth Community Table Tennis Club Community Interest Company | London | 2025 |
| Aintree Circuit Club Events Limited | Liverpool | 2014 |
| Aintree Circuit Club Limited | Liverpool | 1979 |
| Aintree Motor Cycle Racing Club Limited | Liverpool | 1985 |
| Aintree Racecourse Developments Limited | Liverpool | 2006 |
| Ainyfit Limited | Southampton | 2015 |
| Aionequine Limited | Saffron Walden | 2018 |
| AIP Heritage Ltd | Brighton | 2025 |
| Aiphrodesia Ltd | London | 2025 |
| Air Adventures Wales Ltd | Haverfordwest | 2018 |
| Air Arena Limited | Manchester | 2015 |
| Air Artist Agency Limited | London | 2009 |
| Air Assault UK Ltd | Port Talbot | 2019 |
| Air Bounce Inflatables Park Limited | Scunthorpe | 2023 |
| Air Dance Limited | London | 2014 |
| Air Dance Productions Limited | London | 2022 |
| Air Events Ltd | Church Fenton | 2025 |
| Air Extreme Ltd | Barnstaple | 2016 |
| Air Films Limited | London | 2024 |
| Air Haus Meadowhall Limited | Doncaster | 2026 |
| Air Highness Occasions Ltd | Liverpool | 2024 |
| Air Jump (Southern) Limited | London | 2016 |
| Air Jump Limited | London | 2015 |
| Air Kings Ltd | Nottingham | 2015 |
| Air Management Limited | Watford | 2006 |
| Air Pilates Ltd | Liverpool | 2026 |
| Air Race Limited | London | 2025 |
| Air Review Ltd | Cumnock | 2025 |
| Air Rifle Hub Limited | Huntingdon | 2025 |
| Air Screens Inflatables Ltd | Wolverhampton | 2015 |
| Air Sports Group Limited | London | 2019 |
| Air Sports Network Ltd | Brentwood | 2013 |
| Air Supply Skydiving Limited | Nottingham | 1989 |
| Air Westward Limited | Honiton | 1982 |
| Air-Britain (Events) Ltd | Haywards Heath | 1983 |
| Air-Tastic Bangor Ltd | Newry | 2016 |
| Air-Tastic Belfast Ltd | Newry | 2016 |
| Air-Tastic Craigavon Limited | Newry | 2018 |
| Air-Tastic Ltd | Newry | 2016 |
| Air-Tastic Newtownabbey Ltd | Newry | 2019 |
| AIR400 Ltd | Loughborough | 2026 |
| Aira Pilates Ltd | Glasgow | 2025 |
| Airacro Gymnastics Ltd | Haywards Heath | 2025 |
| Airborn Films Limited | Watford | 2010 |
| Airborn Flying Community Interest Company | Birkenhead | 2013 |
| Airborn Productions Limited | Watford | 1983 |
| Airborne Activities Limited | Taunton | 2018 |
| Airborne Adventures Headcorn Ltd | Ashford | 2000 |
| Airborne Adventures Limited | Skipton | 1988 |
| Airborne Assault Limited | Circular Road South | 2008 |
| Airborne Coaching Limited | Iver | 2019 |
| Airborne Events Limited | Ipswich | 2021 |
| Airborne Fit Limited | Ipswich | 2017 |
| Airborne Gymnastics Limited | Iver | 2019 |
| Airborne Performance Limited | Ipswich | 2021 |