| Treeco Environmental Ltd | Maghull | 2025 |
| Treeco Ltd | Maghull | 2024 |
| Treeconomics Limited | Exeter | 2011 |
| Treeconomy Ltd | London | 2018 |
| Treecore Limited | Norwich | 2024 |
| Treecosystems Ltd | London | 2020 |
| Treecreeper Arborists Ltd | Berkeley | 2011 |
| Treedao Limited | Poole | 2021 |
| Treefellas Scotland Ltd | Glasgow | 2024 |
| Treefellers Limited | Helsby | 2008 |
| Treefinitive Ltd. | Inverness | 2017 |
| Treeflights | Tregaron | 2008 |
| Treeform ARB Limited | Northwood | 2024 |
| Treefusion Ltd. | Cambridge | 2022 |
| Treekind Ltd | Ellon | 2018 |
| Treelife Limited | Hemel Hempstead | 2012 |
| Treeline Carbon Limited | Stanmore | 2021 |
| Treeline Forestry Limited | Inverness | 2010 |
| Treeline Services Limited | Surrey | 2002 |
| Treeline Woodlands Ltd. | Peebles | 2004 |
| Treelink Ltd | London | 2021 |
| Treelink Northwest Limited | Greater Manchester | 2007 |
| Treelogic Wood Energy Ltd | Inverurie | 2007 |
| Treemanfoo Ltd | London | 2024 |
| Treemans Ltd | Taunton | 2017 |
| Treemasters Limited | Epsom | 1996 |
| Treemedic Limited | Walton On Thames | 2023 |
| Treemendous Oaks Ltd | Colchester | 2024 |
| Treemetrics UK Limited | Glasgow | 2014 |
| Treenity Tree Planting Services Limited | Mayfair | 2023 |
| Treepartner Ltd. | Pitlochry | 2014 |
| Treepartner Training Ltd | Lancaster | 2020 |
| Treepeopleuk Limited | Whitland | 2016 |
| Treerangers Limited | Beckenham | 2013 |
| Trees Against Poverty C.I.C. | London | 2021 |
| Trees and Seeds Limited | York | 2024 |
| Trees and Vegetation Management Limited | Dronfield | 2023 |
| Trees ARE Good CIC | Oakington | 2021 |
| Trees ARE US Limited | Banchory | 2020 |
| Trees for the Planet Limited | Ludlow | 2021 |
| Trees for Tomorrow Ltd | Crymych | 2021 |
| Trees in Forestry Ltd | Windermere | 2025 |
| Trees in Need Limited | Torquay | 2008 |
| Trees in Trust | Wotton-Under-Edge | 2002 |
| Trees of Green Limited | Knaresborough | 2024 |
| Trees of Hope Community Interest Company | Bristol | 2021 |
| Trees on Farms Limited | Southampton | 2024 |
| Trees Please Limited | Corbridge | 2003 |
| Trees Plus Ltd. | Perth | 2002 |
| Trees R US Limited | New Romney | 2015 |
| Trees to Grow Limited | Shrewsbury | 2006 |
| Trees With Roots Ltd | Coldstream | 2023 |
| Trees-Uk of Bromley Limited | Keston | 2017 |
| TREES4BEES Ltd | Manchester | 2024 |
| TREES4GOOD Limited | Gillingham | 2024 |
| TREES4GROWTH Limited | Gillingham | 2024 |
| TREES4LIFE Campaign Ltd | London | 2010 |
| Treesafe Parkcare Ltd | London | 2023 |
| Treesales (Hillpool) Limited | Dudley | 1980 |
| Treesaw Ltd | Leeds | 2023 |
| Treesawrus Ltd | London | 2025 |
| Treescape Cornwall Limited | Newquay | 2025 |
| Treescape Group Ltd | Woodbridge | 2022 |
| Treescape North West Limited | Lancs | 2006 |
| Treescape Oxford Limited | Oxford | 2011 |
| Treescape Tree Services Limited | Abergavenny | 2020 |
| Treescapes Belfast Ltd | Belfast | 2016 |
| Treescapes Consultancy Limited | Kendal | 2005 |
| Treescene Ltd. | Cardiff | 1991 |
| Treesherriff Limited | Cockermouth | 2015 |
| Treesmiths Scotland Ltd | Currie | 2020 |
| Treespace Ltd | Berwick-Upon-Tweed | 2006 |
| Treestory Limited | Edinburgh | 2018 |
| Treestuff Ltd | Blandford Forum | 2020 |
| Treesurge Ltd | Rochester | 2022 |
| Treesurv Limited | Biggar | 2015 |
| Treetape UK Ltd | Edinburgh | 2020 |
| Treetec Consultancy Limited | Arundel | 2010 |
| Treetech & Ground Solutions Ltd | Arbroath | 2024 |
| Treetech Arboricultural Services Ltd | Chipping Norton | 2011 |
| Treetekk Ltd | Wrexham | 2018 |
| Treetop Forestry Limited | Laurencekirk | 2005 |
| Treetop Services (Essex Tree Surgeons) Limited | Sudbury | 2015 |
| Treetops Plants & Nurseries Ltd | Middlewich | 2025 |
| Treetops.Com Limited | Oxfordshire | 2001 |
| Treevolution Ltd | Newbury | 2024 |
| Treevolution SW Ltd | Abertillery | 2024 |
| Treevolution Tree and Hedge Services Ltd | Bishop'S Stortford | 2021 |
| Treewilding CIC | St Andrews | 2024 |
| Treewise (Lincs) Ltd | Spalding | 2013 |
| Treewise Forestry Ltd | Elgin | 2025 |
| Treewise Ltd | Penryn | 2021 |
| Treewise Solutions Limited | Carlisle | 2010 |
| Treewood Harvesting Ltd | Old Harlow | 2010 |
| Treework & Forestry Ltd | East Sussex | 2003 |
| Treework (Tunbridge Wells) Limited | Tunbridge Wells | 2003 |
| TREEWORK24 Ltd | Wolverhampton | 2025 |
| Treeworker Equipment Ltd | Bordon | 2025 |
| Treeworks (West Wales) Ltd | Haverfordwest | 2002 |
| Treeworks Cornwall Ltd | St. Columb | 2018 |