| Austin Timpson Limited | Manchester | 2006 |
| Austin Transport Services Ltd | Bromsgrove | 2025 |
| Austin Trumanns Ireland Limited | Bradford | 2012 |
| Austin Williamson Limited | Leeds | 2017 |
| Australia Aofuta Agrochymistry Ltd | Kenilworth | 2019 |
| Australia Boffo Agricultural Technology Co. Ltd | Manchester | 2021 |
| Australian Card Clothing Limited | Mitcham | 1979 |
| Austria Grieg Piano Group Ltd | Beckenham | 2018 |
| Autac Assemblies Limited | Macclesfield | 2019 |
| Autac Bespoke Limited | Macclesfield | 2024 |
| Autac CV Limited | Macclesfield | 2018 |
| Autac EV Limited | Macclesfield | 2019 |
| Autark Limited | Littlehampton | 2007 |
| Autelier Ltd | London | 2021 |
| Autentisk Invest Limited | London | 2021 |
| Auter Ltd | London | 2025 |
| Authenteak Limited | Gosport | 2015 |
| Authentic Ltd | Kingsbridge | 2019 |
| Authenyimuse Limited | London | 2024 |
| Authoritative Name Server 66 Ltd | London, Southgate | 2026 |
| Authority Limited | Caerdydd | 2015 |
| Authors of Change Ltd | Godalming | 2012 |
| Auticoin Ltd | Chatham | 2015 |
| Autiq AI Limited | Moffat | 2025 |
| Autiquest Health Ltd | Chatham | 2015 |
| Autiquest Ltd | Chatham | 2015 |
| Autism Action UK Limited | London | 2011 |
| Autism Assessment Centre Ltd | Cheltenham | 2023 |
| Autism North West Limited | London | 1997 |
| Autism Scotland Limited | London | 1999 |
| Autism Services | Gillingham | 2007 |
| Autism Wales Limited | London | 1999 |
| Autistic Cards Limited | London | 1966 |
| Auto 100 Limited | Huthwaite | 2009 |
| Auto Addicts Limited | Cranleigh | 2014 |
| Auto BOY Industrial Co., Ltd. | London | 2016 |
| Auto Caier Trading Co., Ltd | Cambridge | 2023 |
| Auto Computer Services Limited | York | 1991 |
| Auto Ecom Ltd | London | 2024 |
| Auto Electric Car Ltd | Ilford | 2020 |
| Auto Electrical Services (Leighton Buzzard) Limited | Dunstable | 1992 |
| Auto Glass York Limited | Egham | 2011 |
| Auto Graphic Limited | Norwich | 2022 |
| Auto Guarantee Ltd | Huddersfield | 2024 |
| Auto High-Tech Co., Ltd | Stafford, | 2011 |
| Auto Italia Ltd | Croydon | 2024 |
| Auto Locksmiths Association Limited | Caerphilly | 2015 |
| Auto Performance Centre Ltd | Batley | 2017 |
| Auto Performance Limited | Stoke-On-Trent | 2003 |
| Auto RAX Manchester Limited | Ashton-U-Lyne | 2008 |
| Auto Refinishers Limited | Mansfield | 1991 |
| Auto Replace Limited | York | 2013 |
| Auto Services (Horsham) Limited | Salfords Redhill | 1963 |
| Auto Shipping Limited | London | 1985 |
| Auto Stocking Limited | Loughborough | 2019 |
| Auto Styling U.K. Limited | Dudley | 2017 |
| Auto Tech (Coachworks) Limited | Castle Douglas | 1986 |
| Auto Transmissions Ltd | Witney | 1999 |
| Auto Turned Products (Northants) Limited | Chichester | 1962 |
| Auto VIZ Limited | Newton-Le-Willows | 2018 |
| Auto Xpress Hire Limited | Edgware | 2010 |
| Auto-Lec Services Ltd | Wetherby | 2008 |
| Auto-Mo Limited | Liverpool | 2010 |
| Auto-Sleepers Limited | Broadway | 1997 |
| Auto-Solve Technology Ltd | Bridgwater | 2012 |
| Auto-Union Competitions Limited | Corby | 2020 |
| Auto-Vent Sheet Metal Co Ltd | Stoke On Trent | 1956 |
| Autobahn Beckenham Limited | Sevenoaks | 1985 |
| Autobahn International Holdings Limited | Coventry | 2017 |
| Autobaler Limited | Blackburn | 2011 |
| Autobrokers Limited | London | 2021 |
| Autocalls Ltd | Gateshead | 2026 |
| Autocar Industry Ltd | Beckenham | 2021 |
| Autocare Pass Limited | Reading | 2025 |
| Autoclassic Investment Ltd | St. Albans | 2014 |
| Autocoding Ltd | Southend-On-Sea | 2024 |
| Autocolour Swindon Limited | Malmesbury | 2013 |
| Autocraft Limited | Workington | 1981 |
| Autocruise Motorhomes Limited | East Yorkshire | 2005 |
| Autodrome Limited | Daventry | 2020 |
| Autofit Limited | Chorley | 2007 |
| Autofitclothing Ltd | Swansea | 2025 |
| Autofix Coventry Limited | Coventry | 2015 |
| Autofix Garages MCR Ltd | Salford | 2013 |
| Autoflow Systems Ltd | Norwich | 2011 |
| Autofold Systems Limited | Sheffield | 2004 |
| Autoglass (UK) Limited | Egham | 2011 |
| Autoglass Bodyrepair Limited | Egham | 1986 |
| Autoglass Distribution Limited | Egham | 1987 |
| Autoglass Limited | Bedford | 2008 |
| Autoglass Windshields Limited | Egham | 2011 |
| Autoguard Automotive Solutions Limited | Camberley | 2021 |
| Autohoods Limited | Sevenoaks | 2007 |
| Autohub Europe Limited | Coventry | 2012 |
| Autoinn Limited | Benfleet | 2023 |
| Autojack Ltd | Dudley | 2016 |
| Autojob.Co.Uk Limited | Much Hadham | 2006 |
| Autoknit Industry Co., Ltd | Beckenham | 2019 |
| Autolime Ltd | Northampton | 2023 |
| Autolink Limited | Hook | 1995 |