| Miles Underground Limited | Bolton | 2023 |
| Milestone Aspirem Limited | Altrincham | 2014 |
| Mill Balk Quarry Ltd | Pocklington | 2020 |
| Mill of Kair Ltd | Montrose | 2004 |
| Mill Technologies Limited | Belper | 2010 |
| Mill Wear Services Ltd | Alconbury | 2020 |
| Millbrex Contracting Limited | Fyvie | 2024 |
| Millenium Group Ltd | London | 2019 |
| Millennia Stratigraphic Consultants Limited | Lechlade | 2004 |
| Millennium OIL & GAS Engineering (UK) Ltd | London | 2019 |
| Million Barrels Ltd | Hayes | 2020 |
| Milltown Gravel Limited | Co Tyrone | 1963 |
| Milner Geological Services Ltd | Larkhall | 2026 |
| Milner Offshore Ltd | York | 2015 |
| Milnsbridge Stone Ltd | Huddersfield | 2023 |
| Milton Integrated Services Ltd | Carluke | 2021 |
| Miltonkcc Ltd | Montrose | 2010 |
| Minblast Ltd | Sandbach | 2014 |
| Mincorp Limited | Rickmansworth | 2025 |
| Mind 4 Mining Limited | Wokingham | 2021 |
| Mine & Quarry Consultancy Ltd | Dundee | 2026 |
| Mine & Quarry UK Ltd | Wells | 2019 |
| Mine Fines Agglomeration Limited | Burnham On Crouch | 2026 |
| Mine Quarry Motorsport Limited | Radstock | 2006 |
| Mine Tech Services (UK) Limited | Wallingford | 2014 |
| Mine Technology Services Limited | Wormley | 2013 |
| Mine to Yours Limited | Chatham | 2019 |
| Mineesia Limited | Cudham | 2014 |
| Minegeotech UK Limited | Wickham | 2024 |
| Minegt Limited | Cardiff | 2021 |
| Miner One Limited | London | 2017 |
| Mineral Analytics Ltd | London | 2022 |
| Mineral Estate Management Limited | Wolverhampton | 2019 |
| Mineral Extraction and Handling Limited | Neath | 1996 |
| Mineral Heritage Limited | Yeovil | 2019 |
| Mineral Investment Group Limited | London | 2020 |
| Mineral Investments Limited | Hinckley | 1996 |
| Mineral Processing Ltd | Doncaster | 2012 |
| Mineral Products Association Restoration Guarantee Fund Limited | London | 1975 |
| Mineral Products Qualifications Council | Matlock | 1983 |
| Mineralis Ltd | London | 2024 |
| Mines Rescue Service Limited | Mansfield | 1996 |
| Mineserve Global Limited | Wigan | 2025 |
| Minetectual Ltd | London | 2021 |
| Minex GEO Ltd | Swansea | 2024 |
| Minexa Limited | Telford | 2024 |
| Minexia Limited | East Grinstead | 2014 |
| Minexia Nominees Limited | Twickenham | 2022 |
| Mining & Engineering Services Ltd | Hemel Hempstead | 2026 |
| Mining 4 Future Limited | Harrow | 2023 |
| Mining Analyst Consulting Limited | Heathfield | 2005 |
| Mining and Mineral Ltd | Horsham | 2014 |
| Mining Competence & Advisory Ltd | Harrogate | 2018 |
| Mining Enterprise Ltd | Cinderford | 2024 |
| Mining Footprint Ltd | Cupar | 2019 |
| Mining Ltd | London | 2020 |
| Mining Plus UK Limited | Guildford | 2018 |
| Mininvest (Eppleton) Limited | Hinckley | 1996 |
| Mininvest Limited | Hinckley | 1996 |
| Minmore (MPS) Limited | Alford | 2012 |
| Minotaur (Norfolk) Limited | Ripley | 2013 |
| Minova International Limited | Barnsley | 2002 |
| Minrec Limited | Perth | 2005 |
| Minsep Limited | Farnborough | 2010 |
| Miscia Ltd | Leeds | 2020 |
| Miskelly Brothers Limited | Belfast | 1953 |
| Mississippi Lime UK Limited | Barnetby | 2022 |
| Misson Sand and Gravel Company Limited | Doncaster | 2001 |
| Mitchell's Motors Ltd | Falkirk | 2016 |
| Mitra Services (Scotland) Limited | Fraserburgh | 2007 |
| Mitsui E&P Ghana Keta Limited | London, | 2008 |
| Mitsui E&P Mozambique Area 1 Limited | London | 2007 |
| Mitsui E&P UK Limited | London | 2011 |
| Mitten Hill Minerals Ltd | Whitby | 2012 |
| MJ Church Recycling Limited | Chippenham | 2013 |
| MJ Geoscience Ltd | London | 2023 |
| Mjam Limited | Didcot | 2003 |
| MJH Masonry Limited | Chesterfield | 2002 |
| MJM Joint Integrity Services Ltd | Morpeth | 2022 |
| MJM Resource Limited | Brechin | 2012 |
| Mjmr Limited | Whitby | 2012 |
| Mjpc Consultancy Limited | Leicester | 2009 |
| Mjrm Piping Limited | Falkirk | 2016 |
| MJS Welding Solution Limited | Livingston | 2020 |
| MJT OIL & GAS Ltd | Beccles | 2016 |
| MK Fisher Contracts Ltd | Leicester | 2019 |
| MK OIL & GAS Ltd | Slough | 2025 |
| MK Rigging Limited | Aberdeen | 2025 |
| MK Survey Limited | Peterhead | 2013 |
| Mkcc (Norfolk) Limited | Norwich | 2024 |
| MLI Electrical Ltd | Hartlepool | 2015 |
| MLN Health Safety & Environmental Consultants Limited | Dundee | 2016 |
| MMB Inspection Ltd | Hwlffordd | 2026 |
| Mmbirdie Consultants Ltd | Montrose | 2022 |
| MMC Southern Limited | Wadebridge | 2007 |
| Mmgg Consultancy Ltd | Aberdeen | 2018 |
| MMH & ABS Engineering Group Ltd | Preston | 2020 |
| MMM Process Engineering Limited | Milltimber | 2007 |
| Mmnh Holdings Ltd | Penrith | 2024 |
| Mmwtech Ltd | Washington | 2021 |