| Mier International Ltd | Education | 2022 |
| Migo London Ltd | Administrative & support | 2026 |
| Migongo Films Ltd | Information & communication | 2014 |
| Mihye Holdings Ltd | Wholesale & retail | 2023 |
| Mike Brown Construction Consultancy Limited | Professional & scientific | 2021 |
| Miki Sensor United Kingdom Ltd. | Manufacturing | 2021 |
| Mili VUT 95 Ltd | Construction | 2025 |
| Mill Parc (NO.1) Management Company Limited | Households | 2002 |
| Millpond (Carshalton) Management Company Limited | Households | 2008 |
| Mimo Hair Ltd | Other services | 2018 |
| Mind the GAP Coaching Ltd | Health & social care | 2024 |
| Mindset Health Consulting Limited | Professional & scientific | 2025 |
| Ming TAK Ltd | Manufacturing | 2024 |
| Minghua Ltd | Hospitality | 2025 |
| Mini Athletics (Kingston and Wimbledon) Limited | Arts & recreation | 2018 |
| Mini Nail Ltd | Other services | 2024 |
| Minoo Food Ltd | Manufacturing | 2025 |
| Mintmed Ltd | Wholesale & retail | 2025 |
| Miracle in August Limited | Information & communication | 2023 |
| Mirinae Limited | Hospitality | 2016 |
| Misbehaviour Records Ltd | Information & communication | 2025 |
| Miss Marple Tour Ltd | Administrative & support | 2022 |
| Misskhair & Beauty Ltd | Other services | 2024 |
| Miswak Health Ltd | Health & social care | 2014 |
| Mitas Digital Technologies Limited | Financial services | 2025 |
| Mitchell's Fleet Wash Ltd | Administrative & support | 2022 |
| Mitec Management Consultancy Ltd | Professional & scientific | 2023 |
| Mitec Management Services Ltd | Professional & scientific | 2023 |
| Mivatech Limited | Professional & scientific | 2014 |
| MJ Refurbishment and Restoration Ltd | Construction | 2025 |
| Mj's Driving School Limited | Education | 2022 |
| Mjtaylor Consulting Ltd | Professional & scientific | 2024 |
| MK Iconium Limited | Administrative & support | 2023 |
| Mkim Trading Ltd | Extraterritorial | 2021 |
| MKY BA Consulting Ltd | Information & communication | 2026 |
| ML Strategies Ltd | Hospitality | 2024 |
| MLH International Ltd | Wholesale & retail | 2025 |
| Mnsk Properties Ltd | Real estate | 2018 |
| Moim Ltd | Professional & scientific | 2020 |
| Molly Morrison Marketing Limited | Professional & scientific | 2019 |
| Monkey Lony Ltd | Real estate | 2025 |
| Monoleak Limited Liability Partnership | | 2022 |
| Montague Road (Wimbledon) Managements Limited | Households | 1971 |
| Montchamp Ltd | Wholesale & retail | 2015 |
| Montre London Limited | Wholesale & retail | 2020 |
| Moonmaarss Consulting Limited | Information & communication | 2018 |
| Moore Flow Ltd | Water & waste | 2022 |
| Moorim Europe Ltd | Wholesale & retail | 2004 |
| Mopane Consulting Limited | Information & communication | 2014 |
| Moravian Point (Bristol) Management Company Limited | Households | 2005 |
| Morcliffe Consulting Ltd | Professional & scientific | 2022 |
| Morespace Design Ltd | Construction | 2013 |
| Morgan Fynwilly Limited | Real estate | 2016 |
| Morro Rocco Ltd | Wholesale & retail | 2024 |
| Mosaic Landscaping Ltd | Administrative & support | 2022 |
| Mostahfiz Gani Photography Ltd | Professional & scientific | 2019 |
| Mostco Ltd | Wholesale & retail | 2020 |
| Motcombe (East Molesey) Residents Association Limited | Households | 1979 |
| Mother of Travel Limited | Administrative & support | 2018 |
| Mothercore Ltd | Health & social care | 2025 |
| Motion Property Group Ltd | Real estate | 2022 |
| Motspur Park Roofing Ltd | Construction | 2014 |
| Mount Wealth Services Ltd | Professional & scientific | 2024 |
| Moveintel Ltd | Information & communication | 2026 |
| Moylgrove Consulting Limited | Professional & scientific | 2025 |
| MP Chauffeur Ltd | Transport & logistics | 2024 |
| MPW & Co. Ltd | Professional & scientific | 2020 |
| MQ Textiles Ltd | Wholesale & retail | 2019 |
| MR & MJS Properties LLP | | 2026 |
| MR Steering Ltd | Manufacturing | 2011 |
| Mr.Jjv Property Services Ltd | Real estate | 2012 |
| Mrjj.London Limited | Wholesale & retail | 2019 |
| MRS OK Tours Limited | Administrative & support | 2025 |
| MRT Property Ltd | Real estate | 2025 |
| MS Security and Communication Services Limited | Administrative & support | 2021 |
| Msbb Limited | Hospitality | 2017 |
| MSJ Electrics Ltd | Construction | 2011 |
| MSP Advance Limited | Professional & scientific | 2004 |
| Msuk Accounting & Business Limited | Professional & scientific | 2010 |
| MTW Copywriting Ltd | Professional & scientific | 2021 |
| Muazzjdk Property Investments Limited | Real estate | 2025 |
| Mugi Investments Limited | Administrative & support | 2014 |
| Muller Properties Ltd | Real estate | 2025 |
| Multicomms Ltd | Manufacturing | 2023 |
| Multiserv Express Ltd | Construction | 2023 |
| Munkiisoft Limited | Information & communication | 2007 |
| Musa Automotive Ltd | Wholesale & retail | 2023 |
| Music Business Advice Limited | Information & communication | 2020 |
| Mutanderis (XYZ) Limited | Other services | 2018 |
| MVW Consultancy Limited | Professional & scientific | 2012 |
| MVW Estates Limited | Other services | 2025 |
| MW Development & Renovation Limited | Construction | 2018 |
| My Homecare Kingston Ltd | Health & social care | 2019 |
| My LK Labs Ltd | Information & communication | 2025 |
| My Real UK Limited | Administrative & support | 2023 |
| N Wazir GDP Limited | Health & social care | 2019 |
| N&H Lettings Ltd | Real estate | 2024 |
| N&M Invest Ltd | Real estate | 2021 |
| N' DO YA Ltd | Hospitality | 2025 |
| N.S.S.A. Ltd | Hospitality | 2017 |