| Austin’Swears Ltd | London | 2026 |
| Australian Football League England Ltd | Wallington | 2010 |
| Austria-Holdings UK Ltd | Burnley | 2018 |
| Autauric Limited | Glasgow | 2000 |
| Authentic Artist Collective CIC | Linlithgow | 2017 |
| Authentic Opera Company Ltd | Birmingham | 2022 |
| Authentic Taekwon-Do Association CIC | Worthing | 2022 |
| Authentically False Productions CIC | Livingston | 2025 |
| Author L Gray Limited | Walsall | 2019 |
| Authors Cafe Limited | Torrington | 2020 |
| Autism in Motorsports (AIM) | Cardiff | 2020 |
| Auto & Marine Aftercare Limited | | 1987 |
| Auto Comps Ltd | Newton Abbot | 2023 |
| Auto Italia South East Limited | London | 2011 |
| Auto-Test Drivers Club (N.I.) Limited | Co Armagh | 1984 |
| Autodoors International (Holdings) Limited | Cheam | 1973 |
| Autodraw Limited | Nottingham | 2008 |
| Autoevents Ltd | Brighton | 2009 |
| Autografix Limited | Bideford | 1994 |
| Autograph ABP | | 1988 |
| Autograph AID Limited | Glasgow | 2001 |
| Autograph Authenticate Limited | Birmingham | 2024 |
| Autograph Design Limited | London | 1995 |
| Autograph Sports Management Limited | London | 2020 |
| Autograph Trading Ltd | London | 2022 |
| Autojeu Theatre Ltd | London | 2019 |
| Autokino Ltd | Saltburn By The Sea | 2019 |
| Automatic Media Limited | London | 2019 |
| Automatic Panic Ltd | London | 2021 |
| Automatic Songs Limited | Harpenden | 1996 |
| Automotive Archiving Limited | London | 2002 |
| Autonomous Arts Factory CIC | London | 2026 |
| Autonomy (Multimedia) Limited | Raunds | 1994 |
| Autonomy Live Ltd | Rochdale | 2021 |
| Autonymic Arts Ltd | London | 2025 |
| Autoplate Midlands Limited | Walsall | 1990 |
| Autosculpt Handmade Limited | London | 2025 |
| Autoshow Events Limited | Stockton-On-Tees | 2022 |
| Autovelocita Racing Limited | Leicester | 2018 |
| Autumn Ace Pigeon Challange Limited | Liskeard | 2026 |
| Autumn in Malvern Festival Limited | Worcestershire | 1996 |
| Autumn Leisure Ltd | Ryehill | 2016 |
| Autumn Lords Associates Limited | Bromley | 2007 |
| Autumn Productions Limited | | 1970 |
| Autumn Sauna Ltd | London | 2024 |
| Auva Music Ltd | London | 2025 |
| Auxilium Conservation Ltd | Macclesfield | 2026 |
| Auxilla Creations Ltd. | Dagenham | 2011 |
| Auxillium Fitness Ltd | Caerphilly | 2025 |
| Auxo Sport Limited | Harrow | 2024 |
| AV Badminton Club Ltd | Wallington | 2024 |
| AV Boxing and Fitness Ltd | Wakefield | 2018 |
| AV Dance Studio Limited | London | 2024 |
| AV Family Ltd | Ashton-Under-Lyne | 2022 |
| AV Music Ltd | Guildford | 2020 |
| AV Productions Ltd | Morpeth | 2020 |
| AV Stumpfl Ltd | Brentford | 2023 |
| AV Teknic Ltd | Lancing | 2019 |
| AV27 Ltd | Chigwell | 2024 |
| AV51 Limited | Liss | 2016 |
| AVA (Rd&D) C.I.C. | Cardiff | 2022 |
| AVA Drag Ltd | Bury St. Edmunds | 2023 |
| AVA Football Academy London Ltd | Stevenage | 2018 |
| AVA on Stage Ltd | London | 2018 |
| AVA Pilates Studio Limited | Liverpool | 2017 |
| AVA Recreation Limited | Eastleigh | 2013 |
| AVA the Anteater and Friends Ltd | Belfast | 2023 |
| Avada Leisure Ltd | Poole | 2021 |
| Avaddon Academy Ltd | Wisbech | 2026 |
| Avaia Pilates & Wellness Ltd | Kirriemuir | 2025 |
| Available Bands Ltd | Sheffield | 2025 |
| Avakak Songs Limited | Milton Keynes | 1998 |
| Avalanche Academy Ltd | Bristol | 2011 |
| Avalanche Adventure Limited | Leicestershire | 2004 |
| Avalanche Collective Ltd | Atherton | 2024 |
| Avalanche Music Agency Ltd | London | 2025 |
| Avalon Equestrian Limited | Larkhall | 2014 |
| Avalon GMV CIC | London | 2024 |
| Avalon Golf Ltd | London | 2024 |
| Avalon Harness Racing Limited | Larkhall | 2024 |
| Avalon Highway Ltd | Clifton | 2018 |
| Avalon International Management Limited | | 1997 |
| Avalon Larp Ltd | London | 2023 |
| Avalon Live Entertainment Limited | | 2005 |
| Avalon Management Group Limited | | 1988 |
| Avalon One Ltd | Sunderland | 2020 |
| Avalon Pilates Limited | Carlisle | 2024 |
| Avalon Promotions Limited | | 1990 |
| Avalon Publishing Limited | | 1997 |
| Avalon Television Limited | | 1993 |
| Avalonage Limited | Eastleigh | 2013 |
| Avama Video & Music Productions Limited | Tunbridge Wells | 2021 |
| Avan Entertainment Limited | Heywood | 2021 |
| Avan Lounge & Bar Ltd | Manchester | 2022 |
| Avance Events Ltd | Guildford | 2020 |
| Avant Art Tattoo Ltd | Chippenham | 2017 |
| Avant Garde Concepts Limited | Newcastle Upon Tyne | 2019 |
| Avant Garde Dance Company | London | 2008 |
| Avant Theatre CIC | Porth | 2017 |
| Avant-Garde Music Limited | Southwark | 2012 |