| Advice North West | 3 Strand Road | 2005 |
| Advice UK | London | 1986 |
| Advice UP Consulting Ltd | New Malden | 2022 |
| Advice With Accounts Nottingham Limited | Nottingham | 2019 |
| Advicesmith Estates Ltd | London | 2022 |
| Advik Solutions Ltd | Coventry | 2018 |
| Adviserly Network Limited | Stamford | 2026 |
| Advisers & Consulting Ltd | London | 2015 |
| Advisers for Deaf Network Ltd | London | 2025 |
| Advising Data Ltd | London | 2024 |
| Advision Plus Ltd | London | 2020 |
| Advisory and Evaluator Services Limited | Derby | 2025 |
| Advisory Management Limited | London | 2016 |
| Advissor Limited | Carlisle | 2018 |
| Adviweb Limited | Whitchurch | 2002 |
| Advntm Limited | Barnsley | 2019 |
| Advoc Europe Limited | Exeter | 2013 |
| Advocacy and Mediation Associates Ltd | Tunbridge Wells | 2025 |
| Advocacy and Mediation Consultants Limited | 15-17 Cumberland Place | 2010 |
| Advocacy Orkney | Kirkwall | 2002 |
| Advocard | Edinburgh | 2011 |
| Advocate Limited | London | 2024 |
| Advocating Together Ltd | Altrincham | 2025 |
| Advox Media Ltd | London | 2026 |
| Advrt Consulting Ltd | Southampton | 2015 |
| ADW Engineering Consultants Ltd | Lincoln | 2016 |
| Adwan Service Ltd | London | 2018 |
| Adwize Limited | London | 2020 |
| ADY (South West) Limited | Clevedon | 2023 |
| ADY Dentals Ltd | Stoke-Sub-Hamdon | 2022 |
| ADY Rail Solution Limited | Harrow | 2015 |
| Adyan Barber Ltd | Stokesley | 2024 |
| Adyan Linen & Laundry Services Ltd | Sutton | 2021 |
| Adyan Linen Hire Limited | Sutton | 2012 |
| Adydas Ventures Limited | London | 2019 |
| Adys Recruitment Consultancy Limited | Stockwell | 1995 |
| Adys Road Property Limited | London | 2012 |
| Adyton Real Estate Ltd | London | 2003 |
| Adytum Limited | London | 2016 |
| Adyy Barbers Limited | Peterborough | 2024 |
| ADZ Barbers Limited | Sheffield | 2024 |
| Adzally Limited | Bristol | 2021 |
| Adzee Limited | Southsea | 2019 |
| Adzeffects Beauty Empire Ltd | London | 2025 |
| Adzenture Ltd | Smethwick | 2021 |
| Adziel Limited | Insch | 1996 |
| Adélie Studios Limited | Gateshead | 2023 |
| AE Barber London Limited | London | 2025 |
| AE Barbers Limited | Camberley | 2023 |
| AE Cars Services Ltd | London | 2016 |
| AE Coaching Limited | Loughton | 2023 |
| AE Drilling Limited | Aberdeen | 2011 |
| AE Edinburgh Nails Ltd | Edinburgh | 2023 |
| AE Estate Planning Limited | Newport | 2022 |
| AE Ferguson Civil Engineering Limited | Lanark | 2022 |
| AE Fitness Ltd | York | 2024 |
| AE Fitting Ltd | Edgware | 2018 |
| AE Food Supplies Ltd | London | 2021 |
| AE Holdings Ltd | Penarth | 2020 |
| AE Promotions Europe Ltd | London | 2012 |
| AE Recruiters Ltd | Newcastle Upon Tyne | 2025 |
| AE Response Medical Ltd | Hungerford | 2024 |
| AE Sales Ltd | Bedford | 2025 |
| AE Traders Ltd | Newcastle Upon Tyne | 2020 |
| Ae-Sthetics MAY Ltd | Chesterfield | 2024 |
| AE1 Ltd | London | 2025 |
| AEA Auto Ltd | Bradford | 2018 |
| AEB Sculpting Limited | London | 2024 |
| AEC London Ltd | London | 2019 |
| Aecom Corp Ltd | London | 2025 |
| Aecom Design Build (Holdings) Limited | London | 1998 |
| Aecor International Scaffolding Safety Services Ltd | Wakefield | 2025 |
| Aecor International Training Ltd | Wakefield | 2024 |
| Aecus Leisure Ltd | Stafford | 2021 |
| AED Productions Limited | Walthamstow | 2019 |
| Aedesiusone Ltd | Beaconsfield | 2022 |
| Aeditions Limited | Stanmore | 2019 |
| Aedma & Co Ltd | London | 2014 |
| Aefald Embroidery Limited | Glasgow | 2015 |
| AEG Media Limited | Manchester | 2020 |
| AEG Traders Ltd | Hull | 2022 |
| Aegean Yachting (International) Company Limited | Romford | 2016 |
| Aegir Consultancy Services Ltd | Doncaster | 2017 |
| Aegis (Torbay) Limited | Devon | 2001 |
| Aegis Alarm Systems Limited | London | 1988 |
| Aegis Coaching Ltd | London | 2025 |
| Aegis Mountain Limited | Ilkley | 2016 |
| Aegis Protection Services Ltd | London | 2025 |
| Aegis Quality Associates Ltd | Lichfield | 2023 |
| Aegle Holdings Limited | Shirley | 2025 |
| AEH Inspection Ltd | Glenrothes | 2021 |
| AEH Services NW Limited | St Asaph | 2024 |
| Aehs Associates Limited | London | 2015 |
| AEI Security & Communications Ltd | East Sussex | 1993 |
| AEI Solutions Limited | Manchester | 2011 |
| Aejz Limited | Essex | 2018 |
| Aekiss Ltd | Loughton | 2016 |
| Aele Services Ltd | Manchester | 2020 |
| Aelina Ltd | Manchester | 2016 |
| Aelithia Ltd | Hull | 2024 |