| Actipaws Limited | Southampton | 2024 |
| Active Agronomy Ltd | North Yorkshire | 2004 |
| Active Crop Solutions Ltd | Melton Mowbray | 2021 |
| Active Forestry Ltd | Harrogate | 1998 |
| Active Paws Nottingham Ltd | Nottingham | 2025 |
| Active Soil Solutions Ltd | Melton Mowbray | 2021 |
| Active Tree Care Ltd | Downton | 2014 |
| Active Treescape Ltd | Glenrothes | 2008 |
| Activeacre Ltd | Market Deeping | 2024 |
| Activus Habitat Services Ltd | Colchester | 2026 |
| Acton Environmental Ltd | Newry | 2021 |
| Acton Farming Company Ltd | Bishops Castle | 2018 |
| Acton Healthcare and Leisure Limited | London | 2018 |
| Acton Mill Care Farm Limited | Worcester | 2009 |
| Actual Pest Control Limited | Middlesex | 2006 |
| Actuality Ltd | Ripon | 2024 |
| Acumen Concept Services Ltd | Chorley | 2011 |
| Acupuncture on Tour Ltd | Doncaster | 2020 |
| ACW Arborists Limited | Alton | 2020 |
| ACW Properties Limited | Chepstow | 1983 |
| Acwarb Ltd | Tamworth | 2024 |
| Acworths Limited | Hungerford | 2026 |
| AD Contracting Limited | Dumfries | 2017 |
| AD Ecology Ltd | Chippenham | 2011 |
| AD Feedstock Ltd | Wymondham | 2015 |
| AD Feedstock Services Ltd | London | 2015 |
| AD Forestry Limited | London | 2024 |
| AD Innovations Limited | Whitehills Business Park | 2014 |
| AD Sport Horses Limited | London | 2024 |
| Ad&Sa Campbell (Milton) Limited | Cairndow | 2022 |
| ADA Cole Memorial Stables | Hapton | 1960 |
| Adam Atkinson Limited | Plymouth | 2012 |
| Adam Farms Limited | Nottinghamshire | 1994 |
| Adam Fitch Limited | Peterborough | 2006 |
| Adam Knock Agricultural Contracting Ltd | Abergavenny | 2022 |
| Adam Pitts Chickens Limited | Taunton | 2009 |
| Adam Rolls Tree Services Ltd | Fareham | 2021 |
| Adam Tait Limited | Fraserburgh | 2007 |
| Adam's Tree Surgery Ltd | Solihull | 2013 |
| Adames (Flansham) Limited | Bognor Regis | 1965 |
| Adams & Howling Limited | Norwich | 1972 |
| Adams Agricultural Limited | Tadley | 2019 |
| Adams Engineering (Marine) Limited | Avoch | 2010 |
| Adams Family Farms Limited | Felixstowe | 2020 |
| Adams Farm Ltd | Ballymena | 2017 |
| Adams Farming Limited | Strangford | 2022 |
| Adams Keyston Hill Limited | Haverfordwest | 2012 |
| Adams Tree Professionals Limited | Shifnal | 2018 |
| Adamsarbor Ltd | Norwich | 2025 |
| Adamson Brothers Ltd | Haltwhistle | 2025 |
| Adamson Contractors Limited | Northallerton | 2006 |
| Adamson Tree Care Limited | Heathhall | 2016 |
| Adamston (Farms) Limited | By Dundee | 1964 |
| Adaptive Farming Limited | Sandbach | 2019 |
| Adaqua Limited | Walsall | 2013 |
| Adavoyle Farm Enterprises Limited | Newry | 2019 |
| Adcocks Minorcas Limited | Spalding | 1948 |
| Addashaw Farm Ltd | Middlewich | 2023 |
| Addgate Limited | Devon | 1998 |
| Addington Fund | Barford | 2003 |
| Addington Manor Estates Limited | Huddersfield | 2018 |
| Addis Farms Limited | Droitwich | 1945 |
| Addison Agricultural Ltd | Wakefield | 2025 |
| Addlestone Honey Limited | Addlestone | 2025 |
| ADE A'I Gwmni CYF | Aberaeron | 2009 |
| Adefbtos Logistics Ltd | Lancaster | 2021 |
| Adele James Pet Services Ltd | Stockport | 2022 |
| Adelina Management Limited | London | 2023 |
| Adenbourne Limited | Bicester | 1998 |
| Adenia Fishing Co. Limited | Lerwick | 1987 |
| Adey Farming Limited | Swadlincote | 2011 |
| ADF Farms Ltd | Romney Marsh | 2021 |
| ADF Tree & Garden Maintenance Ltd | Oxford | 2025 |
| Adforest Ltd | London | 2024 |
| Aditya Organics Ltd | London | 2024 |
| ADK Heaithcare Servlces Ltd | Erith | 2022 |
| ADL Agricultural Limited | Crewe | 2017 |
| Adlg Limited | Grantham | 2025 |
| Adlington Turkeys Limited | Coventry | 2013 |
| ADM (Devon) Limited | Crediton | 2003 |
| ADM Farming Services Ltd | Aberdeen | 2023 |
| ADM TET Ltd | Wigan | 2019 |
| Admergill Hall Farm Ltd | Nelson | 2026 |
| Admington Hall Farms Limited | Cirencester | 1995 |
| Admirals View Alpacas C.I.C. | Shrewsbury | 2025 |
| Admire Bees Ltd | Salisbury | 2025 |
| Adonis Blue Ltd | Crewe | 1991 |
| Adorable Alpacas Ltd | Presteigne | 2022 |
| Adreban Limited | Fraserburgh | 2003 |
| Adrian Bell Livestock Scanning Limited | Cumbria | 2006 |
| Adrian Marsh Limited | Salop | 1998 |
| Adrian Scripps Limited | Tonbridge | 1964 |
| Adrian Waters Limited | Halesworth | 2013 |
| ADS Agricultural Contractors Limited | Barnstaple | 2025 |
| Adski 2000 Limited | Yeovil | 2000 |
| ADT Farriers Ltd | Chichester | 2019 |
| ADT Wildlife Management and Pest Control Limited | Alford | 2024 |
| Aduol Industries Limited | Salford | 2021 |
| Adur Oyster Company Ltd | Shoreham-By-Sea | 2022 |
| Advance Fumigation and Pest Control Limited | Warwick | 1992 |