| Melas (Group) Limited | Wholesale & retail | 1993 |
| Melas Limited | Manufacturing | 1995 |
| Melsturman Ltd | Health & social care | 2017 |
| Melt Clothing Ltd | Wholesale & retail | 2025 |
| Melvaig Associates Limited | Professional & scientific | 2021 |
| Merchantline Distribution Ltd | Wholesale & retail | 2021 |
| Mercore Services Group Limited | Agriculture & fishing | 2015 |
| Mercore Services Limited | Administrative & support | 2012 |
| Mercury Accountants Ltd | Professional & scientific | 2022 |
| Mercury Capital Group Ltd | Administrative & support | 2024 |
| Mercury Garage/Warsop Vale Tyre Service Limited | Wholesale & retail | 2001 |
| Mercury Lettings Ltd | Real estate | 2025 |
| Mercury Software Limited | Information & communication | 2012 |
| Meridian Packaging Machinery Ltd | Manufacturing | 2022 |
| Merlin Cleans Ltd | Administrative & support | 2025 |
| Metrex Electrical Limited | Construction | 2020 |
| Mettam-Spencer Associates Limited | Extraterritorial | 2012 |
| MF Care Group Limited | Wholesale & retail | 2020 |
| MFP Developments Limited | Construction | 2018 |
| MFP Linings Limited | Construction | 2012 |
| MFT (Mansfield) Limited | Construction | 2020 |
| MG Performance Coaching Limited | Other services | 2025 |
| MGB Watches Limited | Wholesale & retail | 2023 |
| MHG Training Limited | Education | 2019 |
| MHO4U Ltd | Health & social care | 2023 |
| MHS Freight Ltd | Transport & logistics | 2026 |
| Michael Birks Specialist Cars Limited | Wholesale & retail | 2020 |
| Michael Whittle Caravans Limited | Hospitality | 2011 |
| Michylee Limited | Professional & scientific | 2024 |
| Mickledale Lane Limited | Professional & scientific | 2017 |
| Micks Tyres Limited | Wholesale & retail | 2009 |
| Midland Commercial Cleaners Limited | Administrative & support | 2001 |
| Midland Drive Limited | Real estate | 2024 |
| Midland Dual Glaze Limited | Construction | 2004 |
| Midland Eyes Ltd | Health & social care | 2019 |
| Midland Garage (Mansfield) Limited | Real estate | 2005 |
| Midland Garden Buildings Ltd | Construction | 2024 |
| Midland Material Testing Ltd | Construction | 2024 |
| Midland Tree Care Company Ltd | Administrative & support | 2013 |
| Midlands Aquisitions Limited | Financial services | 2019 |
| Midlands BAE Medical Aesthetics Ltd | Other services | 2023 |
| Midlands Recycling Solutions Ltd | Water & waste | 2024 |
| Midlands RS Ltd | Water & waste | 2024 |
| Midlands Van Hub Limited | Wholesale & retail | 2026 |
| Midway Retail Ltd | Wholesale & retail | 2019 |
| Miguel Recovery Solutions Ltd | Manufacturing | 2025 |
| Miju Trans Ltd | Transport & logistics | 2017 |
| Mikeleconstruct Ltd | Construction | 2023 |
| Miles Roystone Limited | Extraterritorial | 1967 |
| Military Grade Precision Utilities Ltd | Professional & scientific | 2025 |
| Milkshake Revolution Limited | Wholesale & retail | 2013 |
| Millennium Farm & Pet Supplies Limited | Wholesale & retail | 2020 |
| Miller Knight Fire Doors Limited | Construction | 2020 |
| Miller Knight Group Holdings Limited | Financial services | 2023 |
| Miller Knight Group Investments Ltd | Financial services | 2026 |
| Miller Knight Group Ltd | Financial services | 2024 |
| Miller Knight Investments Ltd | Financial services | 2023 |
| Miller Knight Regeneration Ltd | Construction | 2019 |
| Miller Knight Resource Management Ltd | Construction | 2011 |
| Millers Barbers Limited | Other services | 2012 |
| Millinume Car Limited | Administrative & support | 2023 |
| Millionaire Factory Limited | Information & communication | 2017 |
| Milowe International Ltd | Other services | 2021 |
| Miltruck Ltd | Transport & logistics | 2021 |
| Mind Juice Ltd | Wholesale & retail | 2025 |
| Mind Wealth Holdings Ltd | Financial services | 2025 |
| Mind-Full Counselling & Psychotherapy Services Ltd | Health & social care | 2023 |
| Mindful Living Co Ltd | Wholesale & retail | 2020 |
| Mindscale Ltd | Wholesale & retail | 2026 |
| Mines Rescue Service Limited | Mining & quarrying | 1996 |
| Mini Trattoria Ltd | Hospitality | 2024 |
| Minnie Chester Investments Ltd | Real estate | 2021 |
| Mira Traders Limited | Wholesale & retail | 2025 |
| Mirage Automotive Ltd | Wholesale & retail | 2024 |
| Mirical Transfers Ltd | Manufacturing | 2023 |
| Miss Teddy Limited | Wholesale & retail | 2016 |
| Missy Empire Limited | Wholesale & retail | 2018 |
| Mitchell Fire Protection Limited | Public administration | 2007 |
| Mitchells Ironmongers Limited | Wholesale & retail | 1995 |
| Mitrica Group Ltd | Transport & logistics | 2019 |
| Mitton Electrical Limited | Construction | 2008 |
| MJ Belle Ltd | Real estate | 2022 |
| MJ Motor Company (2023) Limited | Wholesale & retail | 2023 |
| MJA Rail Consultancy Ltd | Administrative & support | 2018 |
| Mjcs Property Maintenance Ltd | Construction | 2017 |
| Mjfs (Midlands) Ltd | Professional & scientific | 2020 |
| MJH Property and Investment Ltd | Real estate | 2026 |
| MJH Roofing Ltd | Construction | 2018 |
| Mjkw Limited | Real estate | 2023 |
| MJM Properties Investments Ltd | Real estate | 2024 |
| MJR Productions Ltd | Information & communication | 2022 |
| Mjrg Engineering Services Ltd | Professional & scientific | 2025 |
| Mjrw Contracting Limited | Agriculture & fishing | 2020 |
| MJS Electrical Systems Limited | Construction | 2007 |
| MJW Property Developments Limited | Construction | 2019 |
| MK & SON Decorating Ltd | Construction | 2025 |
| MK Alliance Group Ltd | Hospitality | 2016 |
| MK Moran Ltd | Health & social care | 2022 |
| MKN Investments Ltd | Real estate | 2022 |
| ML GAS & Heating Solutions Ltd | Construction | 2026 |