| Mellor Turbine Services Ltd | Professional & scientific | 2017 |
| Melt Down Catering Limited | Wholesale & retail | 2016 |
| Melton Trailer Services Ltd | Wholesale & retail | 2025 |
| MEN of Megin C.I.C. | Education | 2026 |
| Menace Industries Ltd | Hospitality | 2026 |
| Mental Fitness Ltd | Other services | 2024 |
| Meraki Nest Limited | Construction | 2024 |
| Mercatronix Ltd | Manufacturing | 2023 |
| Mercer Care Ltd | Health & social care | 2012 |
| Mercury Cleaning Services Ltd | Administrative & support | 2020 |
| Mercury Plastics Limited | Wholesale & retail | 2002 |
| Meredith Civil Engineering Limited | Construction | 2025 |
| Meredith Farmers Ltd T/As ST Vincent Civils Ltd | Construction | 2007 |
| Merit Construction and Development Limited | Construction | 2024 |
| Merit Properties Limited | Real estate | 2005 |
| Merlin & Griffon Estates Ltd | Real estate | 2025 |
| Merlin Aviation Services Ltd | Professional & scientific | 2022 |
| Merlin Generators Limited | Wholesale & retail | 2019 |
| Meronda Limited | Professional & scientific | 2016 |
| Merrigan Holdings Limited | Financial services | 2024 |
| Mesha Consulting Limited | Information & communication | 2012 |
| Mesora Ltd | Professional & scientific | 2021 |
| Metaxa S Ltd | Real estate | 2024 |
| Metheringham Construction Limited | Construction | 1968 |
| Metheringham Gym Limited | Arts & recreation | 2019 |
| Methodise Limited | Information & communication | 2019 |
| Metier Services Limited | Administrative & support | 2009 |
| Metis Aerospace Ltd | Public administration | 2011 |
| Metis Property Limited | Real estate | 2022 |
| Metis Recruitment Ltd | Administrative & support | 2023 |
| Mewspeak Ltd | Professional & scientific | 2013 |
| MG Rental Property Ltd | Real estate | 2026 |
| MGB Exports Limited | Wholesale & retail | 2015 |
| MGB Supplies Limited | Wholesale & retail | 2014 |
| MGM Joinery Services Ltd | Construction | 2016 |
| Mgosal Limited | Real estate | 2017 |
| Mgosal Properties Ltd | Real estate | 2021 |
| MGS Landscaping & Construction Ltd | Construction | 2023 |
| Mgsh Developments Limited | Real estate | 2026 |
| MGT Vehicles Limited | Extraterritorial | 2021 |
| MH900 Bowling Ltd | Wholesale & retail | 2025 |
| MHC Construction Lincoln Ltd | Construction | 2018 |
| MHG Enterprises Limited | Hospitality | 2005 |
| Mhuri Ltd | Professional & scientific | 2025 |
| MI Johnson (Holdings) Limited | Professional & scientific | 2014 |
| MI Johnson Limited | Agriculture & fishing | 2001 |
| Miall Property Limited | Real estate | 2025 |
| Micah Vision Limited | Professional & scientific | 2025 |
| Michael Carter Limited | Administrative & support | 1971 |
| Michael Lewis Transport Ltd | Transport & logistics | 2022 |
| Michael Phong LE Ltd | Education | 2025 |
| Michaelgate (Lincoln) Management Company Limited | Households | 2004 |
| Michaelgate Management Company Limited | Households | 1995 |
| Michal Velky Ltd | Transport & logistics | 2017 |
| Michelle Spence Limited | Wholesale & retail | 2008 |
| Michims Limited | Wholesale & retail | 2025 |
| Mick Gibson Haulage Ltd | Transport & logistics | 2011 |
| Mico and Kevin Steelworks Specialists Ltd | Construction | 2021 |
| Micro Computronics Limited | Wholesale & retail | 2024 |
| Micrometric Techniques Limited | Professional & scientific | 2004 |
| MID Lincs Limited | Wholesale & retail | 2012 |
| Middle World Farms CIC | Agriculture & fishing | 2026 |
| Middleby Holding UK Ltd | Professional & scientific | 2011 |
| Midland Golf Union Limited | Arts & recreation | 2007 |
| Midland Home Management Company Limited | Other services | 2002 |
| Midland Paincare Limited | Health & social care | 2004 |
| Midlands & East Coast MR2 Roadsters Ltd | Wholesale & retail | 2025 |
| Mighty Investments Limited | Real estate | 2017 |
| MIH Architectural Solutions Limited | Professional & scientific | 2011 |
| Milana Shop Limited | Wholesale & retail | 2016 |
| Miles Mechanical Commercial Ltd | Construction | 2026 |
| Milex Miles Ltd | Transport & logistics | 2024 |
| Mili Holdings Limited | Financial services | 2024 |
| Mill and Hearth Ltd | Wholesale & retail | 2026 |
| Mill Cottage Services Limited | Hospitality | 2023 |
| Mill Cottages Property Ltd | Real estate | 2026 |
| Mill Farm Residents Company Limited | Households | 2002 |
| Mill Lane (New Road) Management Limited | Households | 2010 |
| Mill Park Properties Southwell Limited | Real estate | 2024 |
| Millat Ltd | Wholesale & retail | 2025 |
| Millcroft Development Limited | Construction | 2016 |
| Miller & Murdoch Vehicle Sales Limited | Wholesale & retail | 2026 |
| Miller Commodities Ltd | Administrative & support | 2025 |
| Miller Developments (Ingham) Limited | Construction | 2017 |
| Miller Farriers Limited | Agriculture & fishing | 2018 |
| Miller Urology Ltd | Health & social care | 2019 |
| Millfield Close Tealby Ltd | Households | 2020 |
| Millstone Investments Limited | Real estate | 2023 |
| Millwood Pecunia Ltd | Real estate | 2024 |
| Milyanli Investment Ltd | Real estate | 2025 |
| Mima Group Limited | Professional & scientific | 1977 |
| Mimar Studios Ltd | Information & communication | 2023 |
| Mimas Medical Services Ltd. | Health & social care | 2020 |
| MIND4CREATIONS Ltd | Arts & recreation | 2025 |
| Mindframe Ltd | Professional & scientific | 2014 |
| Mindgate Limited | Real estate | 1994 |
| Mindjam Community CIC | Public administration | 2023 |
| Mindjam Limited | Education | 2021 |
| Mindset Mother Ltd | Information & communication | 2025 |
| Minerva Surgery Limited | Health & social care | 2016 |