| Intense Property Management Ltd | Pinner | 2024 |
| Inter Care Limited | Leicester | 1974 |
| Inter City Environmental Consultants Limited | Nottingham | 2010 |
| Inter City Environmental Services Ltd | Nottingham | 2025 |
| Inter County Service Group Ltd | Northamptonshire | 1998 |
| Inter Management Solutions Ltd | Glasgow | 2019 |
| Inter Metal & Scrap Ltd | Abingdon | 2024 |
| Inter Polymer Limited | Cheadle | 2016 |
| Interior Stone Features Limited | Belper | 1983 |
| International Bio-Consultancy Limited | Derby | 1996 |
| International Board for Sustainable Development Ltd | London | 2024 |
| International Digital Solutions Ltd | Glasgow | 2009 |
| International Handling Ltd | Wokingham | 2019 |
| International Innovations Finance & Project Management Ltd | London | 2019 |
| International Recycling Services Limited | Sutton Coldfield | 2010 |
| International Tech Collect Limited | Staines-Upon-Thames | 2025 |
| International Waste Management Group Limited | Bilston Glen | 2000 |
| International Waste Recycling Ltd | Pontypool | 2019 |
| International Water Management Group Limited | London | 2024 |
| Interplas Limited | Camberley | 2020 |
| Interplas Recycling Limited | Camberley | 2020 |
| Interwaste Limited | Lincoln | 2001 |
| Into Services Limited | London | 2018 |
| Intu Waste Removal Limited | Glasgow | 2025 |
| Inutec Limited | Marlow | 2002 |
| Invasive Plant Management Ltd | Cheadle | 2025 |
| Invasive Weed Solutions Limited | Congleton | 2004 |
| Inven Green Recycling Ltd | Cardiff | 2020 |
| Inven PLC | London | 2020 |
| Inveresk Clearances & Removals Ltd | Musselburgh | 2025 |
| Invert Surveys Limited | Lye | 2014 |
| Invertech Drainage Solutions Ltd | Clevedon | 2022 |
| Inverurie Skip Hire Limited | Inverurie | 2014 |
| Invicta Metal Services Ltd | Canterbury | 2016 |
| Invicta Water Treatment Limited | Redhill | 2002 |
| Invixon Holdings Limited | Horncastle | 2024 |
| Invixon Limited | Horncastle | 2014 |
| Invjmg Ltd | | 1989 |
| Inwaste Hixon Ltd | Stafford | 2024 |
| Ioan Falati Ltd | Milton Keynes | 2020 |
| Ionel Mechanic Limited | Bristol | 2022 |
| Ionex SG Limited | Kibworth Beauchamp | 2011 |
| Ionic Technical Services Ltd | Horsham | 2022 |
| Ionic Technologies (Belfast) Limited | Belfast | 2026 |
| Ionizingenergy Limited | Taunton | 2013 |
| Ionpure Technologies Ltd | Saffron Walden | 2003 |
| Ionsep Water Technologies Limited | Glasgow | 2018 |
| IOW Animal Bedding Limited | Ryde | 2024 |
| IP Polymers Ltd | Hull | 2016 |
| IP Recycling Limited | Sheffield | 2021 |
| Ipadea Limited | Corby | 2021 |
| IPE (Salamons Way) Ltd. | Ingatestone | 2008 |
| Ipolish Group Ltd | Willenhall | 2024 |
| IPR Environmental Limited | Wimborne | 2017 |
| Ipsum Drainage Solutions Limited | Chorley | 2013 |
| Ipsum Survey Solutions Limited | Chorley | 2011 |
| Ipswich Utilities Limited | Ipswich | 2014 |
| Ipzone Limited | London | 2015 |
| IQ Bowsers Ltd | Bedford | 2025 |
| IQ Recycling Solutions (NI) Ltd | Magherafelt | 2020 |
| Irecycle International Limited | Sunderland | 2024 |
| Irecycle Ireuse Limited | Weston-Super-Mare | 2022 |
| Irecycle Waste Ltd | Ilford | 2026 |
| Irena Cleaning Ltd | Ilford | 2020 |
| Irish Waste Management Limited | Country Down | 1999 |
| Irish Waste Recycling Limited | Country Down | 2011 |
| Irish Waste Services Limited | Country Down | 1971 |
| Irm-Group Ltd | Bradford | 2024 |
| Iron Bins Clearance Ltd | London | 2025 |
| Iron Daisy Ltd | London | 2011 |
| Iron Daisy Recycling Ltd | London | 2019 |
| Iron Waste Developments Limited | Manchester | 2025 |
| Iron Works Metal Recycling Limited | Poole | 2015 |
| Iron-Lead Industrial Services Ltd | Dundee | 2026 |
| Irongate Services Ltd | Harlow | 2026 |
| Ironman Leeds Limited | Bradford | 2022 |
| Ironstone Trading Group Ltd | Hornchurch | 2026 |
| IRRI-G8 Limited | Leicester | 2013 |
| Irrifence Ltd | Leicester | 2007 |
| Irrigation and Water Limited | Haverhill | 2010 |
| Irrigonics Limited | Gateshead | 2004 |
| IRS Energy Limited | Belfast | 2012 |
| Irwell Street Metal Co. Limited | Bury | 1975 |
| IS Pumps Engineering Limited | Norwich Norfolk | 2021 |
| Isaac Gardening Ltd | Coventry | 2021 |
| Isaac Services Limited | Loughton | 2026 |
| Isaclearspace Solutions Limited | Great Yarmouth | 2026 |
| Iscom Limited | Daventry | 2010 |
| Iscreate Ltd | London | 2024 |
| Iseki Vacuum Systems Limited | Daventry Northampton | 2002 |
| ISL Skip Hire Limited | Birmingham | 2010 |
| Islamic Relief Clothing Collections Ltd. | Birmingham | 2011 |
| Island Environmental Hygiene Ltd | Stockbridge | 2001 |
| Island Waste Services Limited | High Wycombe | 1981 |
| Island Water Services Ltd. | Llansadwrn | 2004 |
| Island Wide Refuse Limited | Portsmouth | 2026 |
| ISM Holdings Limited | Greater Manchester | 2000 |
| ISM Land Consultancy Limited | Deal | 2012 |
| ISM Resource Materials Ltd | London | 2026 |
| Ismay Asbestos Services Ltd | Basildon | 2021 |