| Adavis Limited | Stockton-On-Tees | 2014 |
| Adawood Limited | London | 1968 |
| Aday Accountancy Services Limited | Cullompton | 2024 |
| Aday Landscaping Ltd | Watford | 2025 |
| Aday Suarez Ltd | London | 2015 |
| Adaya Management Limited | Lancaster | 2015 |
| Adayaalam | Surrey | 2016 |
| ADB Accountancy Limited | Harpenden | 2024 |
| ADB Accounts Midlands Limited | Bromsgrove | 2018 |
| ADB Acorn Ltd | Wirral | 2022 |
| ADB Advisory Limited | Thame | 2019 |
| ADB Alarms Group Ltd | Stoke-On-Trent | 2017 |
| ADB Architectural Design and Planning Ltd | Bracknell | 2021 |
| ADB Atelier Limited | London | 2026 |
| ADB BSL Interpreting Limited | Macclesfield | 2025 |
| ADB Consult Limited | Maidenhead | 2011 |
| ADB Consultants Ltd | London | 2025 |
| ADB Consulting Limited | London | 2020 |
| ADB Consulting Services Limited | Southam | 2017 |
| ADB Finance Solutions Ltd | Broadbridge Heath | 2021 |
| ADB Financial Services Limited | London | 2023 |
| ADB FMS Limited | London | 2017 |
| ADB Health Solutions Limited | Newcastle Upon Tyne | 2019 |
| ADB Installations Ltd | Sheerness | 2026 |
| ADB ITL Global Limited | London | 2025 |
| ADB Limited | Hampshire | 2002 |
| ADB Management Limited | Altrincham | 2026 |
| ADB One Ltd | Aylesbury | 2019 |
| ADB Pipeline Access Limited | Blackpool | 2012 |
| ADB Rail Consulting Ltd | Brighton | 2019 |
| ADB Safety and Training Limited | Bath | 2017 |
| ADB Secure Electrical Services Ltd. | Bristol | 2021 |
| ADB Surveying Limited | Rotherham | 2001 |
| ADB Technology Limited | Banchory | 2018 |
| Adbacs Limited | Hereford | 2005 |
| Adbc Ltd | | 2003 |
| Adbd Management Limited | Birmingham | 2018 |
| Adbe Financial Limited | Orpington | 2018 |
| Adbecc Limited | Chester | 2025 |
| Adbell Advisory Limited | London | 2012 |
| Adbetter Ltd | London | 2019 |
| Adbh Advisory Limited | Ipswich | 2021 |
| Adbh Ltd | London | 2013 |
| Adbikes Media Limited | Hampshire | 1997 |
| Adbis Services Limited | London | 2013 |
| Adbit Limited | Burnley | 2011 |
| Adblitz Ltd | Glasgow | 2023 |
| Adbloom Solutions Ltd | St Albans | 2023 |
| Adbluemedia Ltd | London | 2023 |
| Adbo Limited | Chertsey | 2015 |
| Adbols Limited | Milton Keynes | 2018 |
| Adbolton Limited | Leamington Spa | 2004 |
| Adbond Packaging Consulting Ltd | Farnham | 2017 |
| Adboostuk Ltd | Manchester | 2025 |
| Adbr Limited | Stockport | 2014 |
| Adbrium Media Ltd | Birkenhead | 2025 |
| Adbro Controls Limited | Thatcham | 1998 |
| Adbrookes Ltd | Walsall | 2025 |
| Adbugs Limited | Lisburn | 2005 |
| Adbyad Ltd | London | 2021 |
| Adbzk Ltd | Wolverhampton | 2021 |
| ADC Accountancy Limited | Sutton Coldfield | 2012 |
| ADC Accountants Cranleigh Ltd | Cranleigh | 2024 |
| ADC Accountants Limited | Wigan | 2009 |
| ADC Architecture Limited | Chelmsford | 2021 |
| ADC Atelier Ltd | Isleworth | 2021 |
| ADC Berkshire Limited | Winnersh | 2024 |
| ADC BIO EOT Limited | London | 2025 |
| ADC Brown Ltd | Cambridge | 2020 |
| ADC Consultancy Services Ltd | London | 2025 |
| ADC Design and Concepts Limited | Robertsbridge | 2014 |
| ADC Design Limited | Worcester | 2018 |
| ADC Energy Limited | Aberdeen | 1986 |
| ADC Engineering Limited | Newton-Le-Willows | 2006 |
| ADC Engineering Services Ltd | Leeds | 2025 |
| ADC Europe Limited | Borehamwood | 2018 |
| ADC Financial Ltd | Old Stevenage | 2007 |
| ADC Holdings Limited | Stevenage | 2016 |
| ADC Infrastructure Limited | Nottingham | 2013 |
| ADC International Consultants Ltd | London | 2025 |
| ADC Marketing Ltd | Kenilworth | 2024 |
| ADC Power Ltd | Newcastle Upon Tyne | 2018 |
| ADC Services International Limited | Sandy | 1996 |
| ADC Solutions Limited | Burnley | 2001 |
| ADC Surv Ltd | Wellingborough | 2022 |
| ADC Therapeutics (UK) Limited | Reading | 2014 |
| ADC Training Limited | Oswestry | 2022 |
| ADC Vision Design Limited | London | 2024 |
| Adca (Scotland) Limited | Sanquhar | 2011 |
| Adca Ltd | London | 2025 |
| Adca Partners Limited | London | 2026 |
| Adcad Solutions Ltd | Hinckley | 2025 |
| Adcal Holdings Limited | Bucks | 2003 |
| Adcal Professional Services Limited | Stonehouse | 2016 |
| Adcam Creative Limited | London | 2025 |
| Adcam Works Ltd | London | 2025 |
| Adcamap Ltd | London | 2010 |
| Adcap Ltd. | London | 2021 |
| Adcd Consulting Limited | Ilminster | 2022 |
| Adcel Ltd | Farnham | 2013 |