| Mickeys Cafe Limited | Hospitality | 2024 |
| Mickleover, Day Nurseries Ltd. | Education | 1991 |
| Micro Estates Ltd | Real estate | 2022 |
| Micro Fit Gyms Limited | Extraterritorial | 2020 |
| Microleague Limited | Professional & scientific | 1986 |
| Micronet World Limited | Information & communication | 2015 |
| Microring Limited | Manufacturing | 1976 |
| Microwave Marketing Limited | Extraterritorial | 1997 |
| Microwave Technology Ltd | Manufacturing | 2006 |
| MID Catering Ltd | Hospitality | 2019 |
| MID General Building Ltd | Construction | 2021 |
| MID Point Surveys Ltd | Construction | 2024 |
| Mida Civil Engineering Limited | Construction | 2020 |
| Mida Holdings Limited | Construction | 2020 |
| Mida Plant Hire Limited | Administrative & support | 2020 |
| Midas Electronic Services Limited | Manufacturing | 2016 |
| Middle Stone Archaeology Ltd | Administrative & support | 2023 |
| Middlemore Stores Ltd | Extraterritorial | 2020 |
| Middleton Cheney Residents Management Company Limited | Real estate | 2024 |
| Middleton Farm Enterprises Limited | Extraterritorial | 2013 |
| Middleton Livery Ltd | Agriculture & fishing | 2026 |
| Midi Security Limited | Wholesale & retail | 2024 |
| Midland Asset Management Limited | Wholesale & retail | 2011 |
| Midland Build & Developments Ltd | Construction | 2017 |
| Midland Environmental Services Limited | Other services | 2004 |
| Midland Finishing Ltd | Construction | 2025 |
| Midland GAS & Plumbing Service Ltd | Construction | 2025 |
| Midland Meat Packers Limited | Manufacturing | 1970 |
| Midland Medical Company Limited | Health & social care | 2016 |
| Midland Scaffolding Services (Holdings) Limited | Professional & scientific | 1996 |
| Midland Scaffolding Services Limited | Construction | 1982 |
| Midland Site Management Ltd | Construction | 2024 |
| Midland Tiling Ltd | Construction | 2005 |
| Midland Trade Stringing Service Limited | Other services | 1978 |
| Midlands Accident Repair Center Ltd | Wholesale & retail | 2020 |
| Midlands Catering Equipment Limited | Manufacturing | 2020 |
| Midlands Electrical Ltd | Construction | 2012 |
| Midlands Jointing Services Ltd | Construction | 2026 |
| Midlands Kitchen Duct Cleaning Ltd | Administrative & support | 2023 |
| Midoni Brickwork Ltd | Construction | 2021 |
| Midoni Ecom Limited | Wholesale & retail | 2025 |
| Midshires Electrical & Lighting Limited | Wholesale & retail | 2003 |
| Midshires Holdings Limited | Wholesale & retail | 2015 |
| Midsomer Dental Care Limited | Health & social care | 2008 |
| Miecatel JOH Ltd | Wholesale & retail | 2024 |
| Mifex Group Limited | Professional & scientific | 2012 |
| Mific Limited | Financial services | 2017 |
| Mighty Hands Ltd | Health & social care | 2020 |
| Mighty Malinois Hospitality Ltd | Hospitality | 2024 |
| Migrate Point Ltd | Professional & scientific | 2025 |
| MIH IT Solutions Ltd | Information & communication | 2016 |
| MIH Property One Ltd | Real estate | 2018 |
| Mihai Chirila Ltd | Transport & logistics | 2015 |
| Mihai Polizu Ltd | Transport & logistics | 2023 |
| Mihai Silviu Ltd | Transport & logistics | 2025 |
| Mihai T&D Ltd | Transport & logistics | 2018 |
| Mihaita Expert Delivery Ltd | Transport & logistics | 2025 |
| MIJ Developments Ltd | Real estate | 2016 |
| MIK Investments Limited | Real estate | 2022 |
| Mika Developments Limited | Real estate | 2004 |
| Mika Trans Ltd | Transport & logistics | 2011 |
| Mike Alexander Ltd | Extraterritorial | 2015 |
| Mike Angel Ltd | Real estate | 2025 |
| Mike Carroll Limited | Construction | 2013 |
| Mike Mcmanus Limited | Professional & scientific | 2005 |
| Mike Musanu Films Ltd | Information & communication | 2026 |
| Mike Salt Limited | Administrative & support | 2009 |
| Mikeberltin Construction Ltd | Construction | 2023 |
| Mikeli Construction Ltd | Construction | 2018 |
| Mikeniel D Consultancy Limited | Information & communication | 2019 |
| Miklosi Group Solution Ltd | Transport & logistics | 2024 |
| Miko Studio Ltd | Other services | 2025 |
| Mikolaj Trans Ltd | Transport & logistics | 2014 |
| Mikunshotit Ltd | Professional & scientific | 2026 |
| Mila Beauchamp Limited | Hospitality | 2024 |
| Milad Fast Food Ltd | Hospitality | 2026 |
| Milanovi Ltd | Transport & logistics | 2021 |
| Milcomm Ltd | Information & communication | 2019 |
| Milele Grill Ltd | Hospitality | 2008 |
| Milent Limited | Manufacturing | 2024 |
| Miles Industrial Electronics Limited | Information & communication | 1999 |
| Milestone House Solutions Ltd | Professional & scientific | 2020 |
| Milestones Project Consultants Limited | Professional & scientific | 2006 |
| Milex Systems Ltd | Information & communication | 2019 |
| Mili's Hand Car Wash Ltd | Other services | 2016 |
| Military Precision Plumbing Services Limited | Construction | 2018 |
| Milk Interior (UK) Limited | Wholesale & retail | 2013 |
| Milk Mentors C.I.C. | Health & social care | 2024 |
| Mill Race 2023 Ltd | Wholesale & retail | 2023 |
| Mill Race Properties Ltd | Real estate | 2025 |
| Millar Search International Limited | Administrative & support | 2014 |
| Millbro Installations Limited | Construction | 2010 |
| Millbrook Business Finance Ltd | Financial services | 2020 |
| Millbrook Business Group Ltd | Financial services | 2025 |
| Millbrook Capital Ltd | Financial services | 2021 |
| Millbrook Cottages Limited | Extraterritorial | 2001 |
| Millbrook Utilities Ltd | Hospitality | 2023 |
| Millennium Court RTM Company Ltd | Households | 2015 |
| Millennium Grill Limited | Hospitality | 2024 |
| Millennium Onsite Limited | Manufacturing | 2019 |