| Malaika Store Ltd | Wholesale & retail | 2019 |
| Maldivesresearch | Professional & scientific | 2008 |
| Malex Automotive Limited | Wholesale & retail | 2008 |
| Malhi Capital Holdings Ltd | Construction | 2023 |
| Mammoth Mining Limited | Wholesale & retail | 2013 |
| MAN With a Van Midlands Limited | Transport & logistics | 2003 |
| Mana Properties Ltd | Real estate | 2018 |
| Managed Property Lets Limited | Real estate | 2017 |
| Mango and the Moon Living Ltd | Wholesale & retail | 2021 |
| Manna Capital Limited | Financial services | 2025 |
| Manor Farm Apartments Ltd | Real estate | 2017 |
| Manor View Burbage Ltd | Real estate | 2022 |
| Manor View Gardens (Overseal) Management Company Limited | Households | 2020 |
| Manuka Honey (Europe) Limited | Administrative & support | 2021 |
| Maqga Ltd | Professional & scientific | 2025 |
| Mario-Lucas Logistics Ltd | Transport & logistics | 2015 |
| Mark Stacey Beauty Lounge Ltd | Other services | 2024 |
| Mark Whittle Golf Ltd | Wholesale & retail | 2024 |
| Marketedge Online Ltd | Wholesale & retail | 2026 |
| Marketing 786 Strategies Ltd | Information & communication | 2024 |
| Marstone Installations Limited | Construction | 2018 |
| Martin’S Printing Ltd | Manufacturing | 2020 |
| Martyn Rees Electrical Services Ltd | Construction | 2023 |
| Marula Projects Ltd | Hospitality | 2019 |
| Maruti Properties Limited | Real estate | 2012 |
| Marvin Frith Ltd | Construction | 2019 |
| Mary B. Limited | Real estate | 1980 |
| Marydene Court Management Company Limited | Households | 1993 |
| MAS Architecture Limited | Professional & scientific | 2007 |
| MAS Theatre & Voice Ltd | Arts & recreation | 2016 |
| Mason Court (Hinckley) Management Company Limited | Professional & scientific | 1996 |
| Mason Engineering Limited | Professional & scientific | 2025 |
| Mason's (Midland) Limited | Wholesale & retail | 2023 |
| Masovia Ltd | Transport & logistics | 2016 |
| Matt Booton Financial Services Limited | Professional & scientific | 2018 |
| Matt Hogg Ltd | Arts & recreation | 2025 |
| Matt Merry Roofing Limited | Construction | 2020 |
| Maverick Property Services Ltd | Real estate | 2003 |
| Mayday Maintenance Limited | Other services | 2005 |
| Mayflower Gardens (Burbage) Residents Management Company Limited | Households | 2016 |
| Mazwi Ltd | Health & social care | 2020 |
| MB Executive Motor Company Limited | Wholesale & retail | 2024 |
| MB Property Management Limited | Real estate | 2012 |
| MB Telematics Ltd | Administrative & support | 2026 |
| MBH & Sons Ltd | Extraterritorial | 2020 |
| Mbob Ltd | Information & communication | 2025 |
| Mcarthur Gardens Management Company Ltd | Households | 2022 |
| Mcbride Avionics Ltd | Manufacturing | 2017 |
| MCS Facilities Limited | Administrative & support | 2012 |
| MCS Group Leicester Ltd | Administrative & support | 2025 |
| Meah Holdings Limited | Financial services | 2010 |
| Medacta UK Limited | Manufacturing | 2004 |
| Medalin Holdings Ltd | Financial services | 2020 |
| Medalin Limited | Manufacturing | 1994 |
| Medical Staff Ltd | Health & social care | 2023 |
| Medifeet Foot Health Practice Ltd | Health & social care | 2012 |
| Medipod Limited | Information & communication | 2009 |
| Meera Consultancy Ltd | Professional & scientific | 2015 |
| Meetrooms Ltd | Professional & scientific | 2017 |
| Megha Drinks Limited | Wholesale & retail | 2022 |
| Meid Properties Limited | Construction | 2022 |
| Meladys Logistic Ltd | Transport & logistics | 2020 |
| Menzies Consulting Services Ltd | Information & communication | 2018 |
| Meridian Building Ltd | Real estate | 2021 |
| Meridian Narrowboats Limited | Administrative & support | 2006 |
| Meridianxp Limited | Wholesale & retail | 2019 |
| Merlyn Media Limited | Arts & recreation | 2015 |
| Mesk Developments Ltd | Construction | 2022 |
| Metasport Ltd | Professional & scientific | 2018 |
| Mfac Ltd | Professional & scientific | 2023 |
| Mg-Luca's Ltd | Transport & logistics | 2025 |
| MGC Paving Limited | Construction | 2019 |
| MGC Roofing Limited | Construction | 2024 |
| MI Installations Limited | Construction | 2003 |
| MIC Property Solutions Ltd | Construction | 2023 |
| Michelle Kemp Photography Ltd | Professional & scientific | 2020 |
| Michrome Electro-Plating Limited | Manufacturing | 1964 |
| Mickle Hill Trading Ltd | Agriculture & fishing | 2018 |
| Middlefield 1965 Limited | Extraterritorial | 2014 |
| Middlefield Court (Hinckley) Limited | Real estate | 1997 |
| Midland Bowling Supplies Ltd | Wholesale & retail | 2023 |
| Midland Helicopters Limited | Wholesale & retail | 2005 |
| Midland Motorhouse Ltd | Wholesale & retail | 2018 |
| Midland Property Developers Limited | Real estate | 2017 |
| Midland Sign and Lighting Limited | Construction | 2003 |
| Midlands Golf Limited | Wholesale & retail | 2014 |
| Midlands Load Movers Ltd | Transport & logistics | 2024 |
| Midlands Vehicle Group Ltd | Wholesale & retail | 2026 |
| Midshires Electrical Limited | Construction | 2007 |
| Midshires Property Ltd | Real estate | 2025 |
| Mikail Enterprises Limited | Hospitality | 2022 |
| Mike Holdings Limited | Real estate | 2016 |
| Mike Moore & Associates Limited | Information & communication | 2023 |
| Millers Green Associates Ltd | Information & communication | 2022 |
| Millican Catering Ltd | Hospitality | 2021 |
| Milson Hill Limited | Information & communication | 2026 |
| Mindful ME Nursery Group Ltd | Health & social care | 2020 |
| Mineral Investments Limited | Mining & quarrying | 1996 |
| Minigreen Limited | Transport & logistics | 2017 |
| Mininvest (Eppleton) Limited | Mining & quarrying | 1996 |