| M.A.C.S Cool Limited | Energy | 2015 |
| M.Belton & SON Limited | Transport & logistics | 1961 |
| Mabh Investments Ltd | Real estate | 2025 |
| Mackenzie Innes Limited | Other services | 2002 |
| Madehost Ltd | Wholesale & retail | 2023 |
| Madnese Limited | Manufacturing | 2021 |
| Mafa Site Services Ltd | Construction | 2023 |
| Maggie's Content Farm Ltd | Other services | 2026 |
| Magic Moon Ltd | Extraterritorial | 2016 |
| Magical Marking (Holdings) Limited | Professional & scientific | 2007 |
| Magnum Oils Limited | Manufacturing | 2012 |
| Maharaja Marquees Limited | Administrative & support | 2003 |
| Maison Signature Ltd | Wholesale & retail | 2026 |
| MAJ Performance Ltd | Education | 2025 |
| Major Gaming Entertainment Ltd | Other services | 2017 |
| Majorwood Studios Ltd | Information & communication | 2022 |
| Make IT Easy Business Solutions Limited | Professional & scientific | 2011 |
| Makin Holmes Limited | Real estate | 2025 |
| Malcolm KAY Housing Limited | Extraterritorial | 2016 |
| Malcolm Victor Property Ltd | Real estate | 2017 |
| Maltings Electrical Ltd | Financial services | 2022 |
| Mama Jude's Kitchen Ltd | Hospitality | 2018 |
| Mamma Wins Pet Supplies Ltd | Wholesale & retail | 2021 |
| Manor Farm Machinery Limited | Agriculture & fishing | 2010 |
| Manor Renewables Limited | Energy | 2013 |
| Manteam Limited | Construction | 1989 |
| Marble-Granite-Quartz Limited | Manufacturing | 2011 |
| Mariner's Auto Technician Services Limited | Wholesale & retail | 2009 |
| Marius CR Limited | Construction | 2020 |
| Mark Eskriett Ltd | Construction | 2024 |
| Mark H Poskitt Limited | Agriculture & fishing | 1956 |
| Marritt Electrical Ltd | Construction | 2022 |
| Marthkat Ltd | Information & communication | 2025 |
| Mason Domains Ltd | Real estate | 2021 |
| Mason Instrumentation Services Ltd | Professional & scientific | 2024 |
| Massie and Partners Ltd | Professional & scientific | 2020 |
| Masters Spreading Limited | Agriculture & fishing | 2017 |
| Matthel Developments Limited | Construction | 2021 |
| Matthews Communications Ltd | Information & communication | 1999 |
| MAW Holdings Limited | Agriculture & fishing | 1991 |
| MAX Aggregates Ltd | Construction | 2023 |
| Mazai Limited | Health & social care | 2008 |
| MC Doners Limited | Hospitality | 2019 |
| MC Joinery & Home Improvements Limited | Construction | 2019 |
| MC82 Limited | Transport & logistics | 2025 |
| Mccann Logistics Ltd | Transport & logistics | 1978 |
| MCD Carriage Limited | Transport & logistics | 2021 |
| Mcem Solutions Ltd | Professional & scientific | 2022 |
| Mcmullen Properties Limited | Real estate | 2025 |
| Meadow Lodge Care Limited | Health & social care | 2007 |
| Mediram Limited | Health & social care | 2020 |
| Medley Construction and Landscaping Ltd | Construction | 2022 |
| Medley Properties LLP | | 2024 |
| Meir Services Limited | Construction | 1996 |
| Memento Mori Yorkshire Ltd | Arts & recreation | 2023 |
| Mercury World Limited | Hospitality | 2023 |
| Metham Limited | Agriculture & fishing | 2003 |
| MF Asset Management Ltd | Real estate | 2016 |
| MG Cladding Services Ltd | Construction | 2014 |
| MG Drive Limited | Professional & scientific | 2024 |
| MGB Roofing Ltd | Construction | 2024 |
| Michelle Louise Boutique Limited | Wholesale & retail | 2025 |
| Midav Holdings Ltd | Real estate | 2019 |
| Midnight Wolves Media Limited | Information & communication | 2026 |
| MIG Night Haulier Ltd | Transport & logistics | 2019 |
| Mike Bulmer Transport Limited | Transport & logistics | 2002 |
| Mill Farm Consultancy Limited | Administrative & support | 2023 |
| Mill Farm Property Limited | Extraterritorial | 2023 |
| Mindshaper Academy Ltd | Administrative & support | 2025 |
| Minibugz Limited | Health & social care | 2016 |
| Ministry of Bloods Limited | Information & communication | 2025 |
| Minster Fisheries Ltd | Hospitality | 2011 |
| Mission Trinity Goole CIC | Hospitality | 2025 |
| Mitchell Financial Services Limited | Financial services | 2016 |
| MJ Delivery Ltd | Transport & logistics | 2026 |
| MJM Total Electrical Limited | Transport & logistics | 2025 |
| Mjpb Investments Ltd | Real estate | 2024 |
| MJR Traffic Ltd | Construction | 2023 |
| MKJ & SBR Property Holdings UK Limited | Real estate | 2026 |
| ML Residential Ltd | Health & social care | 2024 |
| MM Delivery Limited | Transport & logistics | 2017 |
| MMS Property (York) Ltd | Construction | 2020 |
| MNA Group (East Yorkshire) Holdings Limited | Financial services | 2024 |
| Mobile Tyres (Goole) Limited | Wholesale & retail | 2013 |
| Mobility House (Goole) Limited | Wholesale & retail | 2025 |
| Modern Roofing Yorkshire Ltd | Construction | 2024 |
| MOF Consulting Ltd | Public administration | 2018 |
| Moleworks Solutions Ltd | Information & communication | 2023 |
| Monaki Ltd | Wholesale & retail | 2023 |
| Montanaro Growth & Income Fund Limited Partnership NO.3 | | 2004 |
| Moor Marketing Limited | Administrative & support | 2023 |
| Moore & Bailey Cladding Ltd | Construction | 2024 |
| Moorville Management Company Limited | Real estate | 2012 |
| More Than Simple Ltd | Wholesale & retail | 2023 |
| Moreira Services Ltd | Construction | 2023 |
| Morgan Wolff Limited | Administrative & support | 1996 |
| Mortgage Enabling Platform Ltd | Professional & scientific | 2026 |
| Mortimer Canine Academy Limited | Other services | 2024 |
| MOS Agri Ltd | Agriculture & fishing | 2025 |
| Motor-Count Limited | Wholesale & retail | 1985 |