| Marsh FM Consultancy Group Ltd | Professional & scientific | 2024 |
| Martineau Close Management Company Limited | Households | 1983 |
| Mastering Holdings Limited | Financial services | 2019 |
| Masto Consulting Ltd | Information & communication | 2026 |
| Mathew Swales Music Ltd | Administrative & support | 2018 |
| Matthew Kallenberg-Pierce Ltd | Real estate | 1999 |
| Maude Jones Limited | Financial services | 2014 |
| Mawdsley Advisory Limited | Professional & scientific | 2026 |
| Maxxton UK Ltd | Information & communication | 2013 |
| MAY Williams Counselling Ltd | Health & social care | 2023 |
| MBA Properties Limited | Real estate | 2010 |
| MCC19 Limited | Financial services | 2018 |
| Mcmillan Housing Company Limited | Real estate | 2014 |
| Mcnair in Motion Limited | Arts & recreation | 2020 |
| Mcpt Limited | Other services | 2019 |
| Mcwin Limited | Financial services | 2016 |
| MDB Property Developments Limited | Real estate | 2009 |
| Meadows Reach (West Horsley) Management Ltd | Households | 2022 |
| Meadway (Esher) Residents Association Limited | Households | 1989 |
| Meanwhile UK Developments Ltd | Administrative & support | 2025 |
| Measured Media Consulting Ltd | Professional & scientific | 2017 |
| Meddots Ltd | Professional & scientific | 2022 |
| Media Minds Global Ltd | Professional & scientific | 2009 |
| Medina Battery Storage Limited | Energy | 2026 |
| Medina Studios Ltd | Information & communication | 2022 |
| Meera Beers U.K. Ltd | Hospitality | 2003 |
| Meet the Leader Limited | Information & communication | 2017 |
| Mehrart Limited | Wholesale & retail | 2023 |
| Meitner UK Ltd | Administrative & support | 2020 |
| Melanie Wilkinson Nutrition Ltd | Education | 2021 |
| Mellmar Capital Limited | Professional & scientific | 2014 |
| Menopause Care (London) Limited | Health & social care | 2025 |
| Mensano Limited | Financial services | 2016 |
| MEP Planning Services Limited | Construction | 2025 |
| Meraki Beauty Boutique Ltd | Administrative & support | 2017 |
| Merstham Village Shop Ltd | Wholesale & retail | 2015 |
| Metropolitan Police Motor Club Limited | Arts & recreation | 2006 |
| MG Tax Consulting Ltd | Professional & scientific | 2020 |
| MGS Sporting Services Ltd | Other services | 2021 |
| MGT Renaissance Limited | Construction | 2019 |
| Michael George & Associates Limited | Professional & scientific | 2003 |
| Midpoint Consulting Limited | Professional & scientific | 2016 |
| Mildruff | | 1997 |
| Millfield Capital Limited | Financial services | 2023 |
| Milney Consulting Limited | Information & communication | 2024 |
| Minara Services Limited | Real estate | 2011 |
| Mining Risk Consultants Limited | Financial services | 2015 |
| Miss Maid Cleaning Services Limited | Administrative & support | 2025 |
| MJ & LA Taylor LLP | | 2011 |
| MJB HR Consultancy Ltd | Administrative & support | 2025 |
| Mjtm Property Ltd | Real estate | 2009 |
| MJW Consulting Services Ltd | Information & communication | 2023 |
| Mljh Limited | Professional & scientific | 2024 |
| Mmarth Consult Ltd | Professional & scientific | 2024 |
| Mobiroom Limited | Extraterritorial | 2015 |
| Moer Ltd | Information & communication | 2008 |
| Mojo Control Ltd | Information & communication | 2012 |
| Mole Valley Accountants Limited | Extraterritorial | 2005 |
| Momentum Developments Ltd | Real estate | 2018 |
| Mometix Limited | Information & communication | 2016 |
| Monarda Ltd | Information & communication | 2020 |
| Moore Place Developments 2 Limited | Real estate | 2017 |
| Moore Place Developments 3 Limited | Real estate | 2017 |
| Moore Place Developments Limited | Real estate | 2014 |
| Moran (Holdings) Limited | Financial services | 2014 |
| Moran Residentials Limited | Construction | 2014 |
| More & Digital Ltd | Information & communication | 2026 |
| Morgan Design House Limited | Professional & scientific | 2018 |
| Morton Martial Arts Ltd | Education | 2024 |
| Morze Tech Ltd | Information & communication | 2025 |
| Motivation '81 Limited | Arts & recreation | 1976 |
| Mountbatten Gate Management Limited | Real estate | 2000 |
| Move International Ltd | Wholesale & retail | 2012 |
| Moviescreens Limited | Information & communication | 2023 |
| MR & MRS Jones Limited | Professional & scientific | 2018 |
| MR Partners Ltd | Professional & scientific | 2025 |
| MR Whisper Studios Ltd | Information & communication | 2012 |
| MRF Consultancy Ltd | Professional & scientific | 2025 |
| MRX Holdings Limited | Professional & scientific | 2025 |
| MS Technicial Draughting Ltd | Professional & scientific | 2026 |
| MSF Doctor Services Ltd | Health & social care | 2015 |
| MUD Holdco 2 Ltd | Administrative & support | 2025 |
| MUD Holdco Ltd | Administrative & support | 2025 |
| Multipli Limited | Financial services | 2017 |
| Murray Swan Consulting Limited | Professional & scientific | 2016 |
| Muwzo Ltd | Information & communication | 2019 |
| MWA Events Ltd | Administrative & support | 2025 |
| Mybuco Limited | Construction | 2016 |
| Myteaim Ltd | Information & communication | 2025 |
| N&A Homes LLP | | 2023 |
| NAL Investment Properties LLP | | 2023 |
| Naomi Edmonds Ltd | Arts & recreation | 2015 |
| Napier Court Freehold Limited | Households | 2003 |
| Napier Court Management Limited | Households | 1978 |
| Nassaj & Co Limited | Professional & scientific | 2022 |
| Natasha Bowler Ltd | Information & communication | 2023 |
| Nature & Climate Action CIC | Education | 2025 |
| Navitas Renewables Ltd | Professional & scientific | 2011 |
| NBH Business Advisory Services Ltd | Professional & scientific | 2025 |
| NC Programming Solutions Ltd | Professional & scientific | 2022 |