| Mario Clean Kingdom Ltd | Greenford | 2023 |
| Marius Ciuchi Ltd | Dagenham | 2014 |
| Mariz Engineering Solutions Ltd | Hartlepool | 2026 |
| Mark Allsopp Services Ltd | Kings Worthy | 2014 |
| Mark on the Move Ltd | Braintree | 2026 |
| Marke Wasteaway Limited | Broxbourne | 2026 |
| Market Cleaning Services Limited | Dundee | 2018 |
| Market Weighton Metals Limited | Pocklington, | 1965 |
| Marketlodge Limited | | 1985 |
| Marks Metal Recycling Limited | Leamington Spa | 2013 |
| Marks Services and Sons Limited | Essex | 2005 |
| Marldell Water Limited | Petersfield | 2013 |
| Marlow Services Ltd | Rainham | 2017 |
| Marlowe Environmental Services Limited | London | 1987 |
| Marlston Water Company Limited | Thatcham | 2024 |
| Marquette Metal Recycling Ltd | Cardiff | 2013 |
| Mars Waste Management Ltd | Brierley Hill | 2024 |
| Marseclips Ltd | Oxford | 2024 |
| Marsh Services (S.E.) Limited | Longfield | 2002 |
| Marshalls Waste Limited | Dereham | 2025 |
| Marshalls Waste Services Ltd | Middlesbrough | 2024 |
| Marsona Ltd | Normanton | 2021 |
| Marston Environmental Services Ltd | Bedworth | 2003 |
| Martelly Group Ltd. | Bromley | 2022 |
| Martin Cattermole Plumbing & Heating Ltd | Billingham | 2015 |
| Martin Lockyear Utilities Ltd | Luton | 2025 |
| Martin Mone T/A: Martin Mone Transport Limited | Grays | 2019 |
| Martin Skip Hire Limited | King'S Lynn | 2023 |
| Martins of York Limited | York | 2004 |
| Martlands Waste Solutions Ltd | Liverpool | 2009 |
| Marvel B W Services Limited | Chatham | 2025 |
| Marvellous Movers Limited | Harrow | 2022 |
| Marwin Environmental Trading (UK) Limited | Londonderry | 2023 |
| Marylebone Waste Management Ltd | London | 2019 |
| Mase Skip Hire Ltd | Coventry | 2024 |
| Maso Trading Limited | Birmingham | 2024 |
| Mason Metal Recycling Limited | Sheffield | 2014 |
| Mason Metals Limited | Kates Hill Dudley | 2006 |
| Mason Waste Limited | London | 2025 |
| Mason Waste Management Ltd | Cardiff | 2024 |
| Mason-Price Ltd | Swindon | 2007 |
| Masonmovesbristol Limited | Bristol | 2019 |
| Masons Waste Limited | London | 2019 |
| Mass Energy Limited | Preston | 2017 |
| Mass Skip Hire Ltd | Spalding | 2017 |
| Mass Waste and Cleaning Services Ltd | Watford | 2023 |
| Massey's Skip Hire Ltd | Tamworth | 2025 |
| Massimo Services Ltd | Glasgow | 2026 |
| Massive Games Limited | London.E1 7Jf | 1991 |
| Master Blasters North West Ltd | Blackburn | 2025 |
| Master Drains Ltd | Dudley | 2021 |
| Master Muck Ltd | Harrow | 2021 |
| Master Pallets Solution Ltd | Birmingham | 2025 |
| Master Skip Ltd | Dartford | 2001 |
| Master Waste Solutions Ltd | Swansea | 2025 |
| Masterpol Limited | Harrow | 2011 |
| Masters 13 Ltd | Preston | 2020 |
| Masters Collector Services Ltd Ltd | London | 2024 |
| Mata Waste Removal Ltd | London | 2025 |
| Material Change Composting Limited | Wellingborough | 2002 |
| Material Solutions Scotland Limited | Ladybank | 2023 |
| Materialaway Ltd | Warrington | 2026 |
| Materials & Commodities Ltd | Cheshunt | 2020 |
| Materials Recovery Limited | Pendeford Business Park | 2011 |
| Materials Recovery Nominees Limited | High Wycombe | 2004 |
| Mathers & Hirst Limited | Welling | 2007 |
| Matila Services Limited | Oldham | 2025 |
| Matiq Group Ltd | Sheffield | 2025 |
| Matla Alkhaleej General Trading Company Ltd | Birmingham | 2026 |
| Matpro Group Ltd | Glasgow | 2026 |
| Matrix B Ltd | London | 2003 |
| Matrix Biohazard Services Limited | Pencoed | 2008 |
| Matrix Hazard Management Limited | East Boldon | 2024 |
| Matrix MET Corp Limited | London | 2020 |
| Matrix Waste Limited | Newport | 2023 |
| Matrix Water Limited | Northampton | 2022 |
| Matrix Workplace Services Ltd | Pencoed | 2017 |
| Matt Metal Ltd | Slough | 2014 |
| Matt UK Limited | London | 2009 |
| Mattgb Ltd | London | 2023 |
| Matthew Aldcroft Ltd | Wirral | 2025 |
| Matthew Luke Plumbing & Heating Limited | Swindon | 2006 |
| Matthew William Gardiner Limited | Glasgow | 2015 |
| Matthews (Sussex) Limited | Three Bridges | 1992 |
| Matthews Commercial Services Limited | Swansea | 1997 |
| Matthews Environmental Services Limited | Banbury | 2021 |
| Matthias Construction Materials (South-East) Limited | London | 1997 |
| Mattingley Limited | Wantage | 2009 |
| Mattress Recycling Centre Leeds Ltd | Leeds | 2023 |
| Mattress Uplift Services Limited | Paisley | 2025 |
| Matts Metals Ltd | York | 2010 |
| Maugers Limited | Bicester | 2005 |
| Maurice Varney Ltd | Norwich | 2010 |
| Mavencore Water Technologies Ltd | Winsford | 2025 |
| Maverick Pure Water Limited | Seaford | 2024 |
| Maverick Solutions Limited | Edinburgh | 2004 |
| Mavros Solution Limited | London | 2009 |
| Mawla Trading Limited | Redruth | 2017 |
| Mawlaw 673 Limited | Euston Square | 1942 |
| Maws (Services) Ltd | Halesowen | 2016 |