| Luonnosta UK Limited | Wholesale & retail | 2023 |
| Lynx Motorhomes Limited | Wholesale & retail | 2014 |
| M & a Cooling Ltd | Transport & logistics | 2020 |
| M & a Mechanical Services (Lincs) Ltd | Professional & scientific | 2026 |
| M & D Richardson Limited | Transport & logistics | 2006 |
| M & P Heating Limited | Construction | 2008 |
| M&M Grantham Services Ltd | Construction | 2016 |
| M.J. Milson Haulage Limited | Transport & logistics | 2003 |
| M.J.Lawrence Car Sales Limited | Wholesale & retail | 2003 |
| Mackay Business & Investments Ltd | Construction | 2018 |
| Mactrans Ltd | Transport & logistics | 2006 |
| Magik Kandle Limited | Wholesale & retail | 2017 |
| Malo Okukongula | Other services | 2008 |
| Maltby Cleaning Services Ltd | Administrative & support | 2026 |
| Manic Mechanic 18 Ltd | Wholesale & retail | 2018 |
| Manor Farm Business Park Limited | Construction | 2020 |
| Marc Wheatley Construction Limited | Construction | 2012 |
| Marfleet Industries Ltd | Hospitality | 2026 |
| Marian Avenue Homes Ltd | Construction | 2018 |
| Marian Avenue Properties Ltd | Hospitality | 2018 |
| Mariner Consultants Limited | Information & communication | 2011 |
| Mark and Spender Limited | Extraterritorial | 2026 |
| Mark Andrew Vehicle Sales Limited | Wholesale & retail | 2020 |
| Mark Donner Limited | Construction | 2004 |
| Mark Eldin (Wainfleet) Ltd | Wholesale & retail | 2025 |
| Mark Harris (Properties) Limited | Construction | 2009 |
| Mark Lane Designs Ltd | Professional & scientific | 2019 |
| Market Rasen and District Golf Club Limited | Professional & scientific | 1960 |
| Market Rasen Golf Club Limited | Professional & scientific | 2014 |
| Marriott Civils Ltd | Construction | 2007 |
| Marriott Group Holdings Ltd | Professional & scientific | 2016 |
| Martin Commercials Ltd | Wholesale & retail | 2017 |
| Martin Duckworth Limited | Wholesale & retail | 1989 |
| Masonic Links Limited | Extraterritorial | 2023 |
| Materka Consulting Ltd | Professional & scientific | 2018 |
| Matron Ltd | Health & social care | 2019 |
| Maurice Belton Machinery Ltd. | Administrative & support | 1997 |
| MAX Gold Wills Limited | Professional & scientific | 2017 |
| Maxm Investments Limited | Financial services | 2024 |
| MC Blades & SON Ltd | Agriculture & fishing | 2013 |
| Mcardle Diagnostics Ltd | Wholesale & retail | 2026 |
| Mccourt Rigging Limited | Construction | 2018 |
| Mcgruer Maritime Ltd | Professional & scientific | 2017 |
| MCS Cost Consultants Ltd | Professional & scientific | 2023 |
| Meadowsweet Education Ltd | Education | 2026 |
| Media Bricks Ltd | Wholesale & retail | 2022 |
| Meehan Drilling Limited | Water & waste | 2015 |
| Meggitt's Motors Ltd | Wholesale & retail | 2023 |
| Meggitto Gelato Limited | Manufacturing | 2026 |
| Mercom Lincs Ltd | Real estate | 1985 |
| Merlin Falconry Ltd | Agriculture & fishing | 2015 |
| MFT Vintage Ltd | Real estate | 2019 |
| Miava Media Ltd | Information & communication | 2021 |
| Michael Frazer Limited | Financial services | 1995 |
| Michael Miles Limited | Information & communication | 1990 |
| Mickey Mouse Limited | Extraterritorial | 2019 |
| MID Lincs Storage Ltd | Real estate | 2025 |
| Middle Rasen Hand Car Wash Ltd | Administrative & support | 2025 |
| Midlands Managed Properties Ltd | Hospitality | 2019 |
| Millennium Fireworks Ltd | Administrative & support | 2003 |
| Milligan-Manby Farms Ltd | Agriculture & fishing | 2014 |
| Millview Nursery Limited | Agriculture & fishing | 2003 |
| Mindsetfitness Ltd | Arts & recreation | 2026 |
| Miracle Clean Ltd | Administrative & support | 2021 |
| Mister Tinsel Ltd. | Manufacturing | 2015 |
| MJM Auto Reps Limited | Wholesale & retail | 2017 |
| MJP Plant Hire Limited | Construction | 2015 |
| MK Hubs Limited | Wholesale & retail | 2025 |
| MLM Developments (North East) Limited | Construction | 2022 |
| Mmmjc Ventures Limited | Health & social care | 2025 |
| Modernise 76 Limited | Construction | 2024 |
| Modernlogic EOT Trustee Limited | Financial services | 2021 |
| Modernlogic Solutions Limited | Information & communication | 2018 |
| Montagu Square Ltd | Extraterritorial | 2014 |
| Montana (Florida) Limited | Real estate | 2003 |
| Montgomery Cliff Limited | Professional & scientific | 2025 |
| Montgomery Rural Estates Ltd | Real estate | 2025 |
| Monty-Pack Limited | Agriculture & fishing | 2001 |
| Moon Letting Ltd | Real estate | 2015 |
| Moor Ledgers Limited | Professional & scientific | 2023 |
| Moorby Developments Limited | Construction | 2010 |
| Morning Star Medical Ltd | Health & social care | 2012 |
| Mortons of Horncastle Holdings Limited | Extraterritorial | 2019 |
| Mortons of Horncastle Limited | Real estate | 1947 |
| Mota FIX Ltd | Wholesale & retail | 2022 |
| Mother Architects Ltd | Professional & scientific | 2014 |
| Motor Dough Limited | Wholesale & retail | 2020 |
| Motormovers (Lincs) UK Ltd | Wholesale & retail | 2025 |
| Move Right in (UK) Limited | Real estate | 2022 |
| MR Heating Limited | Extraterritorial | 2023 |
| MRC Project Management Ltd | Construction | 2023 |
| Mrvnc Ltd | Administrative & support | 2021 |
| MSP (Lincs) Limited | Construction | 2020 |
| MTD Plastics Ltd | Manufacturing | 2025 |
| N B Window Systems Limited | Construction | 2011 |
| N. Appleyard (Pressure Washing Services) Limited | Other services | 1999 |
| N. Appleyard Holdings Limited | Professional & scientific | 2005 |
| Nanostream Energy Ltd | Manufacturing | 2024 |
| Nashley Care Ltd | Health & social care | 2025 |
| NBE Civils and Groundworks Ltd | Construction | 2025 |