| MJ Watson Transport Ltd | Transport & logistics | 2022 |
| Mj's Stumble Inn Ltd | Hospitality | 2026 |
| MJB Global Ltd | Professional & scientific | 2016 |
| MJB Technical Services Ltd | Professional & scientific | 2010 |
| MJC Auto Solutions Limited | Wholesale & retail | 2020 |
| MJC Coaching & Development Limited | Other services | 2017 |
| MJC CONSTRUCTION1 Ltd | Construction | 2026 |
| MJH Masonry Limited | Mining & quarrying | 2002 |
| MJJ Civil Engineering Limited | Construction | 2009 |
| MJK2 Limited | Information & communication | 2019 |
| MJK7 Limited | Real estate | 2021 |
| MJM Real Estate Limited | Real estate | 2013 |
| MJN Technical Services Ltd | Construction | 2007 |
| MJW Electrical Services Ltd | Construction | 2026 |
| MK Your Performance Limited | Education | 2019 |
| MKH Marketing Ltd | Professional & scientific | 2007 |
| Mkkes Limited | Construction | 2026 |
| MKS Group Limited | Real estate | 2020 |
| MKW Homelets Limited | Real estate | 2025 |
| MLG Integrated Projects Ltd | Construction | 2025 |
| MLH Property Solutions Ltd | Real estate | 2024 |
| MLS Inspections Limited | Manufacturing | 2017 |
| MM Minimarket Ltd | Wholesale & retail | 2023 |
| MM Taylor & SON Industrial Roofing and Cladding Ltd | Construction | 2016 |
| MME Care Limited | Public administration | 2021 |
| MMI Facilities Management Services Ltd | Administrative & support | 2025 |
| MN Enterprises (SY) Ltd | Wholesale & retail | 2022 |
| MNH Plastering Services Ltd | Construction | 2021 |
| MNR Design & Build Limited | Construction | 2021 |
| MNS PUB Management Ltd | Hospitality | 2017 |
| Moante Medicals Limited | Health & social care | 2022 |
| Mobile Caterers Limited | Hospitality | 2025 |
| Mobile Tech Heaven Ltd | Wholesale & retail | 2024 |
| Mobile Towbar Services Ltd | Wholesale & retail | 2004 |
| Mocube Limited | Real estate | 2022 |
| Modco Business Services Limited | Administrative & support | 2014 |
| Mode Media Walls Chesterfield Ltd | Wholesale & retail | 2026 |
| Modern Annexe Group Limited | Construction | 2024 |
| Modular 500 Limited | Construction | 2010 |
| Modular Process Systems Ltd | Manufacturing | 2025 |
| Modular Wiring Systems Ltd | Wholesale & retail | 2014 |
| Moggy Limited | Wholesale & retail | 2025 |
| Mogwai Bars Limited | Hospitality | 2026 |
| Molinari's Ice Cream Ltd | Wholesale & retail | 2003 |
| Mollart-Cox Engineering Limited | Manufacturing | 1995 |
| Mollart-Cox Engineering Trustees Limited | Professional & scientific | 2024 |
| Momentum Educational Psychology Ltd | Education | 2025 |
| Mondo Weirdo Media Limited | Information & communication | 2015 |
| Money Shot Media Limited | Information & communication | 2022 |
| Moneywise Mentor Limited | Professional & scientific | 2021 |
| Monkey Park Community Interest Company | Hospitality | 2014 |
| Monkey Wrench Bespoke Ltd | Administrative & support | 2018 |
| Monkwood Farming and Forestry Ltd | Agriculture & fishing | 2016 |
| Monshaw Limited | Health & social care | 1988 |
| Montello Properties Limited | Real estate | 2014 |
| MOO & DOO Supplies Limited | Wholesale & retail | 2018 |
| MOO MOO MOO LAB Ltd | Hospitality | 2024 |
| Moodle Solutions Limited | Information & communication | 2021 |
| Moonstone and Sage Ltd | Wholesale & retail | 2025 |
| Moor Farm Cottage Ltd | Hospitality | 2023 |
| Moore Sports Massage and PT Ltd | Arts & recreation | 2025 |
| Moorelogic Ltd | Manufacturing | 2022 |
| Moorgate Driver Training Limited | Education | 2022 |
| Moorgate Insurance Services Limited | Financial services | 2023 |
| Moorgate Properties North Limited | Households | 2024 |
| Moorgate Racing Limited | Arts & recreation | 2020 |
| Moorgate Training Limited | Education | 2017 |
| Moorhay Stone and Slate Quarry Ltd | Mining & quarrying | 1997 |
| Moorhead House Investments Ltd | Real estate | 2024 |
| Moorhead House Limited | Real estate | 2021 |
| Moorhill Industries Limited | Wholesale & retail | 2022 |
| Moorside Ltd | Financial services | 1971 |
| Moose Crane & Plant Ltd | Manufacturing | 2017 |
| MOR Pizza Ltd | Hospitality | 2024 |
| Morclean Limited | Manufacturing | 2002 |
| More Expert Ltd | Information & communication | 2020 |
| More Than Glass Limited | Construction | 2017 |
| More Than Sheds Limited | Wholesale & retail | 2024 |
| Morevan Services Limited | Transport & logistics | 2007 |
| Morgan & Burdett Trading AS Tonic Limited | Other services | 2012 |
| Morphix Nutrition Ltd | Households | 2015 |
| Morris (Chesterfield) Ltd | Real estate | 2004 |
| Morris Controls Engineering Limited | Professional & scientific | 2024 |
| Morris Removals Ltd | Other services | 2010 |
| Mortgage 1ST Limited | Financial services | 2008 |
| Mortgage Links Limited | Financial services | 2008 |
| Mortgage Market Ltd | Financial services | 1999 |
| Mortgages & More UK National Limited | Financial services | 2026 |
| Morton Stores Limited | Wholesale & retail | 2007 |
| Morya Ventures Limited | Hospitality | 2024 |
| Mosborough Prescient Limited | Extraterritorial | 2026 |
| MOT Clay Cross Ltd | Wholesale & retail | 2022 |
| Motan Colortronic Limited | Manufacturing | 2009 |
| Motif 8 Limited | Administrative & support | 2003 |
| Motion Finance 2017 Limited | Financial services | 2007 |
| Motion HR Ltd | Administrative & support | 2026 |
| Motor Industry Management Systems Limited | Information & communication | 1997 |
| Motor Select Chesterfield Ltd | Wholesale & retail | 2019 |
| Motor Trade UK Limited | Wholesale & retail | 2023 |
| Motorseeker (UK) Limited | Wholesale & retail | 2007 |