| Hunsley Commercial Ltd | Welton | 2020 |
| Hunt Brown & Sons Limited | Pewsey | 1989 |
| Hunter Business Solutions (NE) Ltd | Bishop Auckland | 2022 |
| Hunter Process Technology Limited | St. Albans | 1981 |
| Hunter Rainn Ltd | Southport | 2022 |
| Hunter Waste Limited | Market Rasen | 2014 |
| Huntley Group Limited | Burnley | 2021 |
| Hunts Recycling Limited | Huntingdon | 2017 |
| Hunts Skips Limited | Tottenham | 2012 |
| Hunts Waste Management Ltd | Loughton | 2018 |
| Hunt’S Drainage and Exterior Cleaning Ltd | Northampton | 2025 |
| Hurley Decarbonisation Solutions Limited | Bridgend | 2021 |
| Hurleys Waste Management Limited | Potters Bar | 2008 |
| Hurlock Waste Removal Limited | Ilford | 2024 |
| Hurn Recycling Devon Limited | Christchurch | 2024 |
| Hurn Recycling Limited | Christchurch | 2011 |
| Hurn Waste Management Services Limited | Christchurch | 2021 |
| Hutchinson Environmental Solutions Limited | Fareham | 1973 |
| Hutton Metal Recycling Ltd | Hornchurch | 2017 |
| Huxmax Ltd | Hainault | 2007 |
| Huzar Service Ltd | London | 2016 |
| HV Energy & Civils Ltd | Newport | 2015 |
| Hvac Commissioning Services Limited | Gateshead | 2011 |
| Hwfe Ltd | East Grinstead | 2024 |
| HWH Energy Limited | Harrow | 2013 |
| HWM (2025) Ltd | London | 1993 |
| HWM Aggregates and Recycling Limited | Cardiff | 2015 |
| Hyde Drainage Services Limited | London | 2021 |
| Hyde Environmental Recycling Limited | Dorchester | 2003 |
| Hyde Wood Topsoil T/A ALL Waste Movements Limited | Rochford | 1994 |
| Hyden Wood Management Company Limited | Petersfield | 2001 |
| Hydra-Clear Process Water Ltd | Warrington | 2015 |
| Hydraguard Limited | Darlington | 2000 |
| Hydrasyst Investments UK Limited | London | 2016 |
| Hydreau Ltd | Sleaford | 2017 |
| Hydro Cleansing Limited | Croydon | 2000 |
| Hydro Descaling Limited | Chatham | 1977 |
| Hydro Environmental Systems Limited | Llanelli | 2013 |
| Hydro Hafnant CYF | Betws Y Coed | 2012 |
| Hydro Solutions Water Treatment Limited | Tamworth | 2016 |
| Hydro-Care Environmental Limited | Rayleigh | 2012 |
| Hydro-Ion Ltd | Omagh | 2026 |
| Hydro-X Air Limited | London | 2016 |
| Hydro-X Water Treatment Limited | London | 1984 |
| Hydroflux Limited | Southport | 2014 |
| Hydrogen Engineering Enhancing Technology Ltd | Warwick | 2014 |
| Hydrogen Refinery Ltd | London | 2021 |
| HYDROL8 Ltd. | Bristol | 2020 |
| Hydrologistics Africa Limited | Cardiff | 2017 |
| Hydrology Group Limited | Leeds | 2017 |
| Hydrology Supplier Limited | Newcastle Upon Tyne | 2020 |
| Hydros Water Solutions Limited | Redditch | 2025 |
| Hydroscape Systems Limited | Chandler'S Ford | 2012 |
| Hydroserve Limited | Halifax | 2010 |
| Hydrostatic Testing Pipeline Services Ltd | Chester | 2016 |
| Hydrosure Limited | Newcastle Upon Tyne | 2017 |
| Hydrotec (UK) Limited | Hughenden Avenue | 1992 |
| Hydrotec Industrial Services Ltd | Brough | 2016 |
| Hydrotec Industries Ltd | Brough | 2025 |
| Hydrotec Overseas Limited | High Wycombe | 2015 |
| Hydrotech Draincare Ltd | Nottingham | 2023 |
| Hydrotech Environmental & Civils Ltd | Taunton | 2018 |
| Hydrotechnics Ltd. | Alloa | 1997 |
| Hydrotek Group Limited | Shipley | 2025 |
| Hydrovax Environmental Ltd | Woking | 2026 |
| Hydroviron Limited | Kingswinford | 2003 |
| Hydrowise Solutions Limited | London | 2025 |
| Hydrus Hygiene Limited | Quorn | 2013 |
| Hygenia Ltd | Wolverhampton | 2022 |
| Hygiacura Waste Management Limited | London | 2025 |
| Hygiene Services (Yorkshire) Limited | Wakefield | 2005 |
| Hygienic Cleaning Company (UK) Ltd | Pershore | 1965 |
| Hygienic Holdings Limited | Cannock | 2017 |
| Hykeham O & M Services Limited | Doncaster | 2010 |
| Hylion Capital Ltd. | Gloucester | 2021 |
| Hyper Waste Management Ltd | Stoke On Trent | 2025 |
| Hyperflow Drainage Ltd | Congleton | 2022 |
| Hyposure Ltd | Blackburn | 2026 |
| Hywel NMP Limited | London | 2021 |
| I & Z Limited | Cardiff | 2012 |
| I and M Pallet Services Limited | Luton | 2012 |
| I Collect London Limited | Ilford | 2025 |
| I Consulting and Engineers Ltd | Blackburn | 2019 |
| I D Recycling and Confidential Destruction Ltd | Bristol | 2018 |
| I D Services G.B. Limited | Coventry | 2003 |
| I E B Contractors Ltd | Uttoxeter | 2020 |
| I G Waste Management Ltd | Mansfield | 2025 |
| I Recycle Waste Management Limited | London | 2018 |
| I T Williams Company Limited | Ruthin. | 1973 |
| I Tippers Ltd | Grays | 2025 |
| I W Drains Limited | Country Down | 2017 |
| I W Hughes Services Limited | St. Asaph | 2010 |
| I Wood Renewables Limited | Bridgend | 2016 |
| I-Drains Limited | Doncaster | 2013 |
| I-Water Ltd | London | 2018 |
| I.C. Woodward & SON Limited | London | 1977 |
| I.C.A & Telemetry Services Limited | Bath | 1997 |
| I.C.E. Metals Limited | Manchester | 2023 |
| I.C.S Civils Ltd | Liverpool | 2026 |
| I.C.T Waste Management Consultancy Ltd | York | 2020 |