| I.I.E.S. (Northern) Limited | Widnes | 1985 |
| I.L.M. (Highland) | Alness | 1994 |
| I.R. Waste Management Ltd | Chesterfield | 2010 |
| I.S. Water Treatment Limited | Norwich | 2023 |
| I.S.L. Waste Care Ltd | Birmingham | 2008 |
| I.V.S International Limited | West Yorkshire | 2000 |
| Iamhemp Ltd | Wilmslow | 2019 |
| IAN Thompson Waste Recycling Ltd | Newcastle Upon Tyne | 2024 |
| IAN Underhill Drainage and Building Specialist Limited | Welling | 2019 |
| IAN Welch Grab Services Limited | Hook | 2014 |
| IB Trading Limited | Basildon | 2021 |
| Ibaka Limited | Ossett | 2026 |
| IBG Waste Removal Ltd | Birmingham | 2020 |
| Ibinhungry Limited | Bristol | 2025 |
| Ibka UK Limited | Milton Keynes | 2013 |
| Ibos Global PTY Ltd | London | 2023 |
| Ibrox Shipping Agency and Haulage Limited | Glasgow | 2013 |
| IBT Services (Southern) Limited | Horsham | 2012 |
| ICA Insulation Ltd | Glasgow | 2025 |
| Ice Clear Developments Ltd | Dartford | 2020 |
| Ice Drainage Ltd | Dartford | 2023 |
| Ice Plumbing & Water Services Limited | Ross-On-Wye | 2003 |
| Ice Utilities Ltd | Leicester | 2019 |
| Iceman Wholesale Ltd | London | 2021 |
| Iclear Property Services Ltd | Sutton | 2024 |
| Icnt Limited | Corby | 2011 |
| Icole Curr Ltd | Glasgow | 2025 |
| Icon Waste Management Ltd | Bury St. Edmunds | 2026 |
| Iconic Pure Water Limited | Bury | 2019 |
| Iconic Recycling Bolton UK Limited | Bolton | 2023 |
| Iconic Recycling Collections NW Ltd | Bolton | 2023 |
| Iconic Recycling Ltd | Manchester Road | 2020 |
| Icosa Water Limited | Stonehouse | 2014 |
| ICT Reverse Asset Management Limited | Lancaster | 2003 |
| ID OIL Ltd | Waltham Abbey | 2026 |
| ID3 Asset Management Limited | Retford | 2008 |
| Idata Destruction Ltd | Southport | 2008 |
| IDE Water Solutions UK Limited | London | 2024 |
| Ideal Contracts Ltd | Brentwood | 2021 |
| Ideal Management Services Limited | Northampton | 2019 |
| Ideal OIL Ltd | London | 2023 |
| Ideal Recovery Ltd | Ilford | 2023 |
| Ideal Recycling Limited | Manchester | 2006 |
| Ideal Solutions (North West) Ltd | Manchester | 2012 |
| Ideal Trade Solutions Ltd | Coventry | 2023 |
| Ideal Waste Disposal Ltd | Gateshead | 2018 |
| IDN Solution Ltd | Dartford | 2022 |
| IEM Management Limited | Liverpool | 2020 |
| Ieuan Valley Pumps Ltd | Porth | 2017 |
| Ifal Limited | Dunstable | 2021 |
| IFC Drainage Limited | Peterborough | 2024 |
| Iffluent Ltd | Helensburgh | 2020 |
| Ifilter Ltd | Louth | 2025 |
| IFO and EGE Enterprise Ltd | Luton | 2021 |
| IFR Services Limited | St Albans | 2002 |
| IGH Group Ltd | Dewsbury | 2026 |
| IGL Recovery Ltd | Peterborough | 2026 |
| Iignite Ltd | Bolton | 2013 |
| IJC Tech Ltd | Leeds | 2026 |
| Ijunk Limited | Glasgow | 2016 |
| Ik-Eco Limited | Gateshead | 2000 |
| Iklean-Group(Uk) Limited | Burton-On-Trent | 2025 |
| Iklean-Sports & Arenas Ltd | Burton-On-Trent | 2023 |
| Ikys Cleanup Crew Ltd | Birmingham | 2025 |
| Illmovethatforyou Ltd | Cardiff | 2025 |
| ILM Recycling Services C.I.C. | Smethwick | 2020 |
| Ilmex Limited | Milton Keynes | 1987 |
| IM Engineering UK Limited | Middlesex | 2006 |
| IM Water Hygiene Specialists Ltd | London | 2025 |
| Imaghine Resources UK Limited | Cambridge | 2026 |
| Imariq Limited | Bradford | 2016 |
| IMB Direct Ltd | Airdrie | 2018 |
| IMC Enviro Ltd | York | 2018 |
| Imet Alloys (Europe) Limited | Livingston | 2015 |
| Imet Alloys Limited | Livingston | 2016 |
| Imet Processing (Europe) Limited | Livingston | 2017 |
| Immediate Waste and Resource Management Limited | Alloa | 2013 |
| Immersive Technology Ltd | Southport | 2021 |
| Impact Environmental Ltd | Derby | 2012 |
| Impact Polymers Limited | Bacup | 2003 |
| Imperator Aggregates & Construction Ltd. | Wincanton | 2021 |
| Imperial Drainage Ltd | West Wickham | 2020 |
| Imperial Metal Recycling Ltd | Ashford | 2023 |
| Imperial Recycling Ltd | London | 2019 |
| Imperial Water Services Company Limited | Epsom | 2004 |
| Improved Wright Ltd | Sheffield | 2026 |
| IMS Global Supply Ltd | London | 2025 |
| IMT International Dialyse Ltd | South Croydon | 2013 |
| IN 2 Services Ltd | Truro | 2020 |
| IN Kind Direct | London | 1996 |
| In-Excess Waste Management Ltd | Hemel Hempstead | 2023 |
| In-Vessel Composting Ltd | Wrexham | 2007 |
| IN2WASTE (UK) Ltd | Fenwick | 2022 |
| IN4TYRES Limited | Wokingham | 2026 |
| Inca Trade Limited | Stanford-Le-Hope | 2005 |
| Inch Recyling Solutions Ltd | Plymouth | 2017 |
| Incitus Partners Ltd | London | 2024 |
| Incremental Business Solutions Ltd | Cardiff | 2015 |
| Indassolnig Ltd | London | 2025 |
| Indaver (NI) Ltd. | Kelvedon | 2008 |