| MAC Plant (Eastern) Ltd | Wholesale & retail | 2020 |
| Mac-Meister Ltd | Real estate | 2009 |
| Macalan Ltd | Real estate | 2014 |
| Macarize Limited | Professional & scientific | 2008 |
| Macbeth 47 Limited | Other services | 2005 |
| Macd's Investment LLP | | 2012 |
| Macdaw Ltd | Real estate | 2021 |
| Mace ENT Ltd | Health & social care | 2011 |
| Macewicz Ltd | Wholesale & retail | 2019 |
| Machine & Pitch Maintenance Limited | Arts & recreation | 2011 |
| Machlo Consultancy Limited | Administrative & support | 2011 |
| Mackenzie Brickwork Ltd | Construction | 2021 |
| Mackenzie Milne Developments Ltd | Construction | 2024 |
| Mackinder Smith Holdings Ltd | Financial services | 2021 |
| Maclean Developments Limited | Real estate | 2025 |
| Maclean Group Holdings Limited | Financial services | 2024 |
| Mactronics Aviation Service Ltd | Manufacturing | 2022 |
| MAD Dog Investments Ltd | Real estate | 2022 |
| MAD House Customs Limited | Extraterritorial | 2024 |
| MAD House Industries Limited | Extraterritorial | 2024 |
| MAD House Projects Limited | Construction | 2024 |
| Madame Waffle Ltd | Hospitality | 2014 |
| Maddie and George Limited | Administrative & support | 2011 |
| Maddog's Winghouse Ltd | Hospitality | 2024 |
| Made Capital Limited | Information & communication | 2021 |
| Made Care Holdings Limited | Information & communication | 2019 |
| Made Holdings Ltd | Information & communication | 2010 |
| Made on the Road Ltd | Information & communication | 2018 |
| Madeleine Grace Property Management Ltd | Real estate | 2020 |
| Mae&Co. Medical Ltd | Health & social care | 2025 |
| Mafi Stays Ltd | Administrative & support | 2023 |
| Maflin Property Limited | Real estate | 2023 |
| MAG Properties (Lincoln) Limited | Real estate | 2024 |
| Mage Technologies Ltd | Wholesale & retail | 2023 |
| Magenac UK Ltd | Manufacturing | 2025 |
| Magezine Publishing Limited | Information & communication | 2004 |
| Magic Touch Property Maintenance Limited | Construction | 2014 |
| Magic WOK 2026 Ltd | Hospitality | 2026 |
| Magichombre Ltd | Information & communication | 2024 |
| Magna Accident Services Limited | Information & communication | 2008 |
| Magna Communications Ltd | Information & communication | 2016 |
| Magna Productions Limited | Wholesale & retail | 2022 |
| Magna Scaffold Limited | Construction | 2020 |
| Magna Spero Ltd | Information & communication | 2025 |
| Magnetar Solutions Ltd | Information & communication | 2018 |
| Magnetic Trans Ltd | Transport & logistics | 2021 |
| Maharaaj Restaurant Ltd | Hospitality | 2023 |
| Maharaz Indian Takeaway Ltd | Hospitality | 2024 |
| Maher Holdings Ltd | Real estate | 2021 |
| Maher Millard Construction Ltd | Construction | 2010 |
| Mahi Private Limited | Transport & logistics | 2020 |
| Mahreen Kitchen Ltd | Hospitality | 2026 |
| Maine Services Limited | Construction | 2007 |
| Mainstream Plumbing & Heating Limited | Construction | 2003 |
| Maintsys Limited | Manufacturing | 1997 |
| Mainword Consultants Limited | Information & communication | 1995 |
| Mair Farms Limited | Agriculture & fishing | 2012 |
| Majestic Parks Ltd | Real estate | 2015 |
| Majik Wine Ltd | Wholesale & retail | 2021 |
| Major Electrical Contractors Ltd | Construction | 2025 |
| Majuba Holdings Ltd | Financial services | 2024 |
| Make an Entrance Limited | Manufacturing | 2005 |
| Makrofoods Fresh Ltd | Wholesale & retail | 2016 |
| Malachy Mcgill Ltd | Professional & scientific | 2018 |
| Malav Ltd | Construction | 2019 |
| Malavia Ltd | Information & communication | 2023 |
| Malcolm Faulder GAS Services Limited | Construction | 2022 |
| Malee Holdings Ltd | Manufacturing | 2022 |
| Malham Consultants Limited | Professional & scientific | 2009 |
| Mallavi Stores Ltd | Wholesale & retail | 2015 |
| Mally Homes Limited | Real estate | 2019 |
| Maln MED Ltd | Health & social care | 2025 |
| MAM Groundworks Ltd | Construction | 2024 |
| Mamma MIA Pizza (Lincoln) Limited | Hospitality | 2018 |
| Mammoth Equipment Ltd | Wholesale & retail | 2014 |
| Mammoth Equipment Trustee Limited | Financial services | 2024 |
| Mammoth Talent Ltd | Professional & scientific | 2025 |
| Mampro Limited | Other services | 1974 |
| Man-Face Ltd | Other services | 2020 |
| Mandy Irons Wellbeing Services Limited | Health & social care | 2026 |
| Mane (Lincoln) Ltd | Other services | 2018 |
| Maneday Ltd | Wholesale & retail | 2020 |
| Manhour Solutions Ltd | Administrative & support | 2024 |
| Manik Lifestyle Express Ltd | Wholesale & retail | 2018 |
| Mann Contracting Ltd | Real estate | 2016 |
| Mann Urology Ltd | Health & social care | 2019 |
| Manor Computers Limited | Other services | 2009 |
| Manor Farm Bloodstock Ltd | Agriculture & fishing | 2023 |
| Manor Farm Thoresway Ltd | Agriculture & fishing | 2020 |
| Manor Gardens Management Company Limited | Households | 2000 |
| Manor Homes (Yorkshire) Limited | Construction | 1984 |
| Manor Homes Property Company Limited | Real estate | 2019 |
| Manor House Estate Management Limited | Real estate | 2013 |
| Manor House Securities Ltd | Real estate | 2002 |
| Manor Leas Infant School | Education | 2012 |
| Manor Leas Junior Academy | Education | 2013 |
| Manor Park Skellingthorpe Ltd | Households | 2019 |
| Manorfields (Lincoln) Management Company Ltd | Households | 2019 |
| Mantes Limited | Information & communication | 2014 |
| Manthorpe Construct Ltd | Construction | 2024 |