| Misfits Mmxix Limited | Wholesale & retail | 2019 |
| Miss Selfie Ltd | Wholesale & retail | 2025 |
| Miss Uganda UK CIC | Other services | 2023 |
| Missionflourish Ltd | Construction | 2022 |
| Mist (London) Limited | Manufacturing | 2011 |
| Mistdale Limited | Other services | 1998 |
| Mistwood Ltd | Real estate | 2026 |
| Mitchell Brook Gardens NO.1 Residents Company Limited | Households | 1989 |
| Mitness Flat Management Company Limited | Households | 1979 |
| MJ Legal Services Limited | Professional & scientific | 2026 |
| MJA Financial Investments Limited | Real estate | 2022 |
| Mjai LE Planner Limited | Construction | 2025 |
| Mjjd Services Ltd | Manufacturing | 2014 |
| MJL Yadao Ltd | Other services | 2012 |
| MJR Business Support Limited | Professional & scientific | 2005 |
| MJS Paving Limited | Construction | 2009 |
| Mjuzi Ltd | Information & communication | 2023 |
| MK Drywall Ltd | Construction | 2019 |
| MK Interiors & Plastering Ltd | Construction | 2025 |
| MK Security Solutions Ltd | Administrative & support | 2019 |
| Mk&R Ltd | Health & social care | 2024 |
| MKB Construction Ltd | Construction | 2023 |
| ML Interiors Ltd | Construction | 2013 |
| ML Medic Ltd | Health & social care | 2024 |
| MLB Construction Service Ltd | Construction | 2024 |
| MLC Bookkeeping Services Ltd | Professional & scientific | 2023 |
| Mlnt Construction Ltd | Construction | 2024 |
| MM Capital Investments Limited | Financial services | 2026 |
| MM2CARE Limited | Financial services | 2019 |
| MMC Global Ltd | Construction | 2017 |
| MMK Building Solutions Ltd | Construction | 2017 |
| MMP Electrics Ltd | Construction | 2026 |
| MMP Haulage Limited | Transport & logistics | 2025 |
| MMR Capital Investments Limited | Financial services | 2026 |
| MNA Property Ltd | Manufacturing | 2020 |
| MND Creative Limited | Wholesale & retail | 2025 |
| MNM Housing Ltd | Real estate | 2024 |
| Mnmroofing Ltd | Construction | 2025 |
| MNS Pharma Consultancy Limited | Professional & scientific | 2023 |
| MNZ Care Service Ltd | Health & social care | 2025 |
| MO Afro Caribbean Limited | Hospitality | 2016 |
| MO Integrated Health Limited | Health & social care | 2025 |
| MOA Nursery Ltd | Health & social care | 2025 |
| Moaf Limited | Health & social care | 2025 |
| Moatel Communications (UK) Limited | Information & communication | 2008 |
| Moatlands Limited | Real estate | 2013 |
| Mobile Midwives C.I.C. | Education | 2024 |
| Moda Design Furniture Ltd | Manufacturing | 2018 |
| Mode MEP Consulting Ltd | Professional & scientific | 2020 |
| Modenik Limited | Wholesale & retail | 2024 |
| Modern Loft Rooms UK Ltd | Construction | 2022 |
| Modupefoods Ltd | Wholesale & retail | 2023 |
| Modus Labs Ltd | Information & communication | 2026 |
| Modus Medicals Ltd | Health & social care | 2024 |
| Mohu Consulting Limited | Information & communication | 2014 |
| Mohu Limited | Information & communication | 2008 |
| Moisturize Ltd | Manufacturing | 2025 |
| Mole Properties Limited | Real estate | 2023 |
| Molecular Products Group Limited | Professional & scientific | 1986 |
| Molecular Products Limited | Manufacturing | 1992 |
| Molines Health Care Limited | Health & social care | 2020 |
| Molnar Paint and Decor Ltd | Construction | 2024 |
| Momentum Media Group Ltd | Professional & scientific | 2024 |
| Momentum Wellbeing CIC | Education | 2026 |
| Monab Medicals Limited | Health & social care | 2024 |
| Monalee Ltd | Real estate | 2026 |
| Moneyfex Ltd | Wholesale & retail | 2016 |
| Moneywise Consultancy Ltd | Professional & scientific | 2023 |
| Moni M Limited | Other services | 2017 |
| Monifi Limited | Financial services | 2026 |
| Monnad Services Ltd | Health & social care | 2020 |
| Monroe Ltd | Information & communication | 2025 |
| Montagu Coachworks Ltd | Wholesale & retail | 2002 |
| Montai Consulting Ltd | Professional & scientific | 2019 |
| Moon CUT Records Ltd | Information & communication | 2026 |
| Mooney Complete Roofing Limited | Construction | 2017 |
| Moonforte Care Limited | Health & social care | 2024 |
| Moonlight Medics Ltd | Administrative & support | 2023 |
| Mooreside Properties Ltd | Real estate | 2022 |
| Moorhall Capital Limited | Real estate | 2022 |
| Moot House Members Club Limited | Hospitality | 2023 |
| Mopheme Limited | Health & social care | 2021 |
| Mopheth Ltd | Wholesale & retail | 2024 |
| Morar Groundwork Ltd | Construction | 2022 |
| More Events Management Ltd | Administrative & support | 2019 |
| Moredot Property Ltd | Real estate | 2024 |
| Morocco Store Management Limited | Households | 1997 |
| Morplan Limited | Wholesale & retail | 1999 |
| Morreale Nursery Limited | Agriculture & fishing | 2010 |
| Morta Limited | Other services | 2015 |
| Mosea&Hussain Limited | Real estate | 2024 |
| Moses Healthcare Services UK Limited | Health & social care | 2019 |
| Mossdoc Limited | Health & social care | 2020 |
| Mostar Medics Ltd | Health & social care | 2023 |
| MOT Training Centre Ltd | Education | 2018 |
| Motability Enterprises Limited | Financial services | 1984 |
| Motherland Market Ltd | Wholesale & retail | 2025 |
| Motor Hub Network Ltd | Wholesale & retail | 2026 |
| Motor Installation Ltd | Wholesale & retail | 2024 |
| Motor Station Ltd | Wholesale & retail | 2022 |