| Ad.X International Exhibition & Display Ltd. | Coatbridge | 1998 |
| AD1 Hub Ltd | London | 2020 |
| AD1TREE Ltd | London | 2025 |
| AD2ONE Limited | Manchester | 2002 |
| AD3 Ltd | Nottingham | 2010 |
| AD6 Ltd | London | 2018 |
| AD60BOS Limited | Fareham | 2025 |
| AD8 Consultancy Ltd | Folkestone | 2015 |
| AD8&CO Ltd | London | 2025 |
| AD9 Ltd | London | 2025 |
| Ad:Vantage Digital Ltd | Worcester | 2013 |
| ADA & Co Accountancy Ltd | Sheffield | 2021 |
| ADA & Co Accounts Ltd | Sheffield | 2019 |
| ADA & Kramer Limited | Barking | 2020 |
| ADA Accountants Ltd | London | 2018 |
| ADA Architects Ltd | Berkhamsted | 2012 |
| ADA Architectural Design Associates Ltd | Southport | 2020 |
| ADA Architectural Design Ltd | London | 2016 |
| ADA Asuz Consultancy Ltd | London | 2018 |
| ADA Business Consultancy Ltd | Chelmsford | 2023 |
| ADA Business Ltd | Enfield | 2023 |
| ADA Composites Ltd | Sandown | 2026 |
| ADA Consult Limited | Bracknell | 2026 |
| ADA Consultants UK Ltd | Enfield | 2024 |
| ADA Corporate Advisory Ltd | London | 2026 |
| ADA Corporation Limited | Uxbridge | 2012 |
| ADA Creative Studios Ltd | Belfast | 2025 |
| ADA Design & Arts Limited | London | 2019 |
| ADA Economics Ltd | London | 2015 |
| ADA Engineering Ltd | Aberdeen | 2022 |
| ADA Galaxy Consulting Ltd | Manchester | 2022 |
| ADA Gray Consulting Limited | Bradford | 2024 |
| ADA Innovation Group Ltd | Newcastle Upon Tyne | 2026 |
| ADA Innovation LAB Limited | Tenterden | 2018 |
| ADA Jusic Illustration Limited | Wallingford | 2015 |
| ADA Law Limited | Ealing | 2019 |
| ADA Leadership Limited | Uttoxeter | 2020 |
| ADA Live Limited | Maidstone | 2024 |
| ADA MAY Designs Ltd | Ongar | 2020 |
| ADA MEP & Consultancy Ltd | London | 2021 |
| ADA Mode Limited | Southampton | 2019 |
| ADA Page Ltd | Wigston | 2017 |
| ADA Photography and Advertising Ltd | Salisbury | 2020 |
| ADA Plans and Architectural Services Ltd | Bolton | 2019 |
| ADA Protech Solutions Limited | Chelmsford | 2024 |
| ADA Solutions (NW) Ltd | Longridge | 2024 |
| ADA Solutions Limited | Waterlooville | 2004 |
| ADA Studio Oban Ltd | Oban | 2021 |
| ADA Trade Co., Ltd. | Beckenham | 2014 |
| Adaa PLC | Londn | 2025 |
| Adaadi Services Limited | Wolverhampton | 2014 |
| Adab Advisory Ltd | London | 2026 |
| Adabroc Ventures Ltd | Falkirk | 2023 |
| Adabrock Development Company Limited | Glasgow | 1997 |
| Adac Engineering Services Limited | Newtonmore | 1992 |
| Adacca Ltd | Abingdon | 2011 |
| Adacel Limited | Harrow | 2021 |
| Adacinbio Ltd | Bury St. Edmunds | 2025 |
| Adactia Consulting Limited | Winchester | 2021 |
| Adage Models & Promotions Agency Ltd | Smethwick | 2016 |
| Adagio Consulting Limited | Exmouth | 1997 |
| Adagio Solutions Limited | Bury | 2011 |
| Adah Designs Ltd | Rainham | 2024 |
| Adahx Ltd | Burton Joyce | 2020 |
| Adail Ltd | Bedford | 2025 |
| Adair Acoustic Design Limited | Axminster | 2010 |
| Adair Appleford Limited | Twickenham | 2023 |
| Adair Associates Limited | Epsom | 2017 |
| Adair Aviation Support Limited | Forest Row | 2015 |
| Adair Compliance Consulting Limited | London | 2019 |
| Adair Creative Limited | Glasgow | 2025 |
| Adair Financial Management Ltd | Stratford-Upon-Avon | 2015 |
| Adair Limited | Epsom | 2001 |
| Adair Media Limited | London | 2008 |
| Adair Richards Associates Ltd | Coventry | 2010 |
| Adair Systems and Software Ltd | Dungannon | 2018 |
| Adaj Engineering Ltd | Kirkcaldy | 2021 |
| Adaknows Ltd | London | 2021 |
| Adalatk Ltd | Hounslow | 2021 |
| Adalchemy Limited | Kenilworth | 2025 |
| Adalia Consultancy Ltd | Upminster | 2016 |
| Adalia Market Ltd | Southend-On-Sea | 2014 |
| Adalid Solutions Limited | Smethwick | 2004 |
| Adalit Limited | Weybridge | 1992 |
| Adaloji Ltd | London | 2021 |
| Adalta Development Ltd | Bolton | 2003 |
| Adalta International Solutions Limited | Amersham | 2000 |
| Adalta Recruitment Ltd | Leatherhead | 2022 |
| Adalvo UK Ltd | London | 2021 |
| Adam Winstock Ltd | London | 2011 |
| Adam & Co Accountancy Limited | Bradford | 2000 |
| Adam & Co Accountants Limited | Bolton | 2008 |
| Adam & Co Accounts Ltd | Birmingham | 2026 |
| Adam & EVE Language Ltd | London | 2024 |
| Adam & EVE World Ltd | London | 2024 |
| Adam & NUH Limited | Birmingham | 2021 |
| Adam & Roger Limited | London | 2015 |
| Adam Abraham Ltd | Nottingham | 2010 |
| Adam Accountancy Limited | Slough | 2016 |
| Adam Accountancy Services London Ltd | Hounslow | 2023 |