| Mjpartysuperstore Limited | Administrative & support | 2019 |
| MJS (Kent) Limited | Hospitality | 2013 |
| MJS Properties (Kent) Limited | Real estate | 2023 |
| MJW Lift Projects Limited | Professional & scientific | 2025 |
| MJZ Engineering Limited | Professional & scientific | 2024 |
| MK Management Facilities Ltd | Hospitality | 2013 |
| MK Pavilions Limited | Hospitality | 2017 |
| MK Restaurant Group Ltd | Hospitality | 2025 |
| MKB Finance Services Limited | Professional & scientific | 2019 |
| MKB Pubs Ltd | Hospitality | 2025 |
| Mkha Properties Limited | Real estate | 2025 |
| Mkir London Ltd | Real estate | 2026 |
| Mkla Limited | Real estate | 2025 |
| MKN Legal Services Ltd. | Professional & scientific | 2010 |
| MKS Accountants Limited | Professional & scientific | 2015 |
| MKS Property Holdings Limited | Real estate | 2019 |
| MLD Lift Services Ltd | Manufacturing | 2016 |
| MLL Horizon Ltd | Administrative & support | 2022 |
| MLR & Co Consulting Ltd | Other services | 2019 |
| MM7 Ltd | Professional & scientific | 2026 |
| Mmamc Solutions Limited | Public administration | 2017 |
| Mnztech Ltd | Information & communication | 2025 |
| Mo-Tag Limited | Health & social care | 2023 |
| Mobula Properties Ltd | Real estate | 2025 |
| Modern Building Services Ltd | Construction | 2018 |
| Modern Garden Furnishings Ltd | Wholesale & retail | 2025 |
| Modern Publicity Services Limited | Information & communication | 1986 |
| Modgas Ltd | Construction | 2018 |
| Modolo Limited | Financial services | 2024 |
| Modus Film Limited | Information & communication | 2012 |
| Mohan Associates Limited | Information & communication | 2017 |
| Mohegan Computer Services Limited | Information & communication | 2023 |
| Mojos Catering Company Ltd | Hospitality | 2022 |
| Monday Hospitality Group Limited | Administrative & support | 2018 |
| Money Sage Ltd | Financial services | 2010 |
| Money Tree Developments Limited | Construction | 2015 |
| Monkey Science Limited | Information & communication | 2021 |
| Monks Orchard Residents Association Limited | Households | 1958 |
| Montpelier Blackheath Limited | Hospitality | 2025 |
| Moodys DIP Sandwiches Ltd | Hospitality | 2025 |
| Moonstone Coaching Ltd | Administrative & support | 2008 |
| Moor Park Group Limited | Real estate | 2018 |
| Mopa Consulting (2026) Ltd | Professional & scientific | 2026 |
| Morcombe Electrical Services Ltd | Construction | 2016 |
| Mordn Consultancy Services Ltd | Administrative & support | 2023 |
| Morena's Electrical and Building Services Limited | Construction | 2020 |
| Morerecruitmentkent. Ltd | Administrative & support | 2010 |
| Morfleet Construction/Heating Ltd | Construction | 2025 |
| Morgan Built Asset Services Limited | Real estate | 2012 |
| Morgan Spencer Limited | Administrative & support | 2001 |
| Morgan Spencer Resources Limited | Extraterritorial | 2004 |
| Moriarty Creative Limited | Administrative & support | 2021 |
| Morpheus Alliance Ltd | Financial services | 2021 |
| Morpheus Building Services Limited | Construction | 2020 |
| Morpheus Development Homes Limited | Real estate | 2017 |
| Morpheus Enterprise Ltd | Financial services | 2021 |
| Morpheus GB Holdings Limited | Financial services | 2025 |
| Morpheus Homes Limited | Construction | 2013 |
| Morpheus Investments Limited | Financial services | 2015 |
| Morpheus Ltd | Financial services | 2022 |
| Morphology Media Limited | Information & communication | 2015 |
| Morrell Consulting Ltd | Information & communication | 2018 |
| Mostlike Ltd | Hospitality | 2020 |
| Mottingham Home Stays Limited | Administrative & support | 2010 |
| Moulds & Dies Limited | Professional & scientific | 1954 |
| Mountain of Amazing Miracles (M.A.M)(Ori-Oke Iyanu)-International Prophetic Revival Ministry (I.P.R.M) Ltd | Education | 2018 |
| Mountain View Investments Limited | Professional & scientific | 2021 |
| Mountsfield Court Investments Limited | Real estate | 2004 |
| Moving Picture (South West) Ltd | Professional & scientific | 2020 |
| Moygannon Limited | Professional & scientific | 2009 |
| Moza Dine Ltd | Hospitality | 2023 |
| Mozaic Estates Limited | Real estate | 2016 |
| MP Flooring Specialists Limited | Construction | 2021 |
| MPH Engineering Limited | Construction | 2020 |
| MR Charger Limited | Construction | 2016 |
| Mrcr Business Services Ltd | Administrative & support | 2016 |
| MRE Consulting Ltd | Information & communication | 2004 |
| MRE Services Ltd | Construction | 2021 |
| MRE Utility Services Limited | Professional & scientific | 2024 |
| MRH Property Management Ltd | Real estate | 2021 |
| Mrlf Services Limited | Construction | 2018 |
| MRS Bouquet Limited | Wholesale & retail | 2021 |
| MS Ventilation Services Limited | Energy | 2025 |
| MSC Plastering & Rendering Contractors Ltd | Administrative & support | 2024 |
| Mseal Properties Ltd | Real estate | 2023 |
| MSK Holdings Limited | Financial services | 2006 |
| MSK Rail Limited | Construction | 2010 |
| MSK Southern Limited | Financial services | 2019 |
| MSK Waste Management and Recycling Limited | Water & waste | 2007 |
| MSO Painting and Decorating Limited | Construction | 2026 |
| MSR Batiments Limited | Real estate | 2017 |
| Mstp Property Ltd | Real estate | 2025 |
| MTB Electrical Services Limited | Construction | 2018 |
| MTW Technical Services Ltd | Construction | 2018 |
| Mullins Commissioning Limited | Professional & scientific | 2024 |
| Mulroe Management Ltd | Wholesale & retail | 2017 |
| Multi Services Holdings Limited | Financial services | 2018 |
| Multi Services Kent Limited | Administrative & support | 1996 |
| Multi Services Kent Logistics Limited | Professional & scientific | 2008 |
| Multi Services Kent Security Limited | Professional & scientific | 2008 |