| Test Development Company Limited(The) | Longparish | 1962 |
| Test Valley Estates Management Ltd | Bury St. Edmunds | 2023 |
| Test Valley Farm Ltd | Stockbridge | 2019 |
| Test Valley Trout (Itchen) Limited | Near Romsey | 1979 |
| Teston Wood Limited | Sittingbourne | 2021 |
| Testquest Limited | Winchester | 1989 |
| Tetbury Forestry Limited | Tetbury | 2015 |
| Tetcetera Ltd | Bideford | 2024 |
| Tethys Aquaculture Limited | Saffron Walden | 2011 |
| Tethys Oysters Ltd | Burry Port | 2016 |
| Tetlow & Sons Limited | Norfolk | 1951 |
| Tetney Farming Limited | Cleethorpes | 2024 |
| Tetra Foal Investments Ltd | Kidderminster | 2026 |
| Tetramarl Marine Ltd | Barton-Upon-Humber | 2025 |
| Tettenhall Horse Sanctuary Limited | Birmingham | 2014 |
| Tewaina Ltd | London | 2018 |
| Texonix Ltd | London | 2025 |
| TEY Farm Systems Limited | Ipswich | 1980 |
| Teydale Farming Limited | Scarborough | 2016 |
| Tezla Energy Ltd. | London | 2010 |
| Tfarming Limited | Exeter | 2011 |
| TFB 2 Limited | Ramsay | 2024 |
| TFD Livery Services Limited | Bristol | 2023 |
| TFL ABC Limited | Nantwich | 1998 |
| TFP Agricultural Services Ltd | Newark | 2012 |
| TFP Ventures Limited | Ely | 2014 |
| TFS Training Consultants Limited | Poulton Le Fylde | 2007 |
| TG & DM Watchorn Limited | Lincoln | 1987 |
| TG Pet Care and Breeder Ltd | Colchester | 2024 |
| TG Services Ltd | Purley On Thames | 2025 |
| TG Tree Services Ltd | Faringdon | 2024 |
| TG1 Holding Ltd | Birchington | 2011 |
| TGB Farms Ltd | Magherafelt | 2024 |
| TGB Treecare Ltd | Dunstable | 2022 |
| Tgffarming Ltd | Ballymena | 2025 |
| TGR Agri (UK) Ltd | Hertford | 1999 |
| TGR Agricultural Services Ltd | Sleaford | 2024 |
| TGR Asset Holdings Ltd | Sleaford | 2024 |
| TGR Horticulture Ltd | Leicester | 2026 |
| TH & CL Johnson Limited | Exeter | 2006 |
| TH & JRB Laity Limited | Falmouth | 2002 |
| TH Equine Ltd | Egham | 2021 |
| TH Shellfish Ltd | Bridlington | 2023 |
| TH Tavener Farming Limited | Ipswich | 2014 |
| TH7 Amadeus Limited | Paignton | 2025 |
| Thackmore Limited | Penrith | 2019 |
| Thackwood Farms Limited | Carlisle | 2006 |
| Thakeham Mushrooms Limited | Bristol | 2011 |
| Thal Farms Ltd | Omagh | 2025 |
| Thame Hens Ltd | Sydenham | 2025 |
| Thames & Chiltern Honey Bees Ltd | High Wycombe | 2022 |
| Thames Carp Tours Limited | Berkshire | 2006 |
| Thames Chase Trust Limited | Pike Lane | 2006 |
| Thames Estuary Lobster Hatchery CIC | Brightlingsea | 2022 |
| Thames Estuary Partnership | London | 1999 |
| Thames Products Limited | Shoeburyness | 2018 |
| Thames Valley Arborists Limited | Hartley Wintney | 2022 |
| Thames Valley Eggs (Production) Limited | Chippenham | 1988 |
| Thames Valley Farriers Ltd | Chinnor | 2019 |
| Thames Valley Tree Care Ltd | Chipping Norton | 2015 |
| Thameside Nature Park Ltd | Colchester | 2010 |
| Thamesmead Growers CIC | London | 2023 |
| Thanet Earth Lettuce Limited | Birchington | 2024 |
| Thanet Earth Peppers Limited | Paddock Wood | 2008 |
| Thanet Growers Four Limited | Birchington | 2008 |
| Thanet Growers One Limited | Birchington | 2007 |
| Thanet Growers Seven Limited | Birchington | 2007 |
| Thanet Growers SIX Limited | Birchington | 2007 |
| Thanet Growers Three Limited | Birchington | 2007 |
| Tharros Limited | Cambridge | 1993 |
| Thatch Barn (Yelling) Limited | St. Neots | 2016 |
| Thatchers Farm Limited | Chelmsford | 1959 |
| Thawley Brothers (New) Ltd | Barnsley | 2013 |
| Thaymar Limited | Retford | 1997 |
| THC Contracting (Hull) Limited | Hull | 2025 |
| THD Equestrian Services Limited | Sutton Coldfield | 2015 |
| THE (Global) Future Forest Company Ltd | London | 2017 |
| THE 110 Farm Limited | Hyde | 2025 |
| THE 95 Club Limited | Hassocks | 2024 |
| THE A'Maize'Ing Feed Company Limited | Arundel | 2005 |
| THE A.R.K. (the Amphibian and Reptile Keeper) Ltd | Hoddesdon | 2024 |
| THE Abercairny Estates Limited | Crieff | 1924 |
| THE Abington Group Limited | Great Abington | 2016 |
| THE Aces Fertility Clinic Ltd | Billericay | 2023 |
| THE Aegir Consultancy Limited | Shetland | 2014 |
| THE African Conservation and Development Foundation | Cambridge | 2007 |
| THE Agricultural Corporation Ltd | Barking | 2017 |
| THE Agricultural RAT Ltd | Gillingham | 2022 |
| THE Agvisor Limited | Bungay | 2020 |
| THE Aire and Ouse Farms Limited | Leeds | 1915 |
| THE Alliance Chippers Limited | Spalding | 2024 |
| THE Allt Beag Armadale Trust | Thurso | 2001 |
| THE Alocasia Company Ltd | Wallasey | 2025 |
| THE Alpaca Ranch Limited | St. Albans | 2024 |
| THE Alpaca Shop Limited | Ongar | 2012 |
| THE Alpaca Trekking and Visitors Centre Ltd | Stirling | 2022 |
| THE Alternative Animal Sanctuary Limited | Cardiff | 2019 |
| THE Althorne Estate Limited | Chelmsford | 2016 |
| THE American Quarter Horse Association UK Limited | Belper | 1975 |
| THE Ancient Trails Company Ltd | Dorchester | 2020 |