| Mahasimhaya (UK) Limited | Wholesale & retail | 2024 |
| Mahi Tahi Ltd | Professional & scientific | 2019 |
| Mahik Holdings Ltd | Financial services | 2024 |
| Maiar Property Management Limited | Real estate | 2026 |
| Maida Vale Apartments Limited | Real estate | 2025 |
| Maison Favrel Ltd | Hospitality | 2013 |
| Maison Wuji Limited | Education | 2025 |
| Maja Tsolo Photography Ltd | Professional & scientific | 2019 |
| Majestic Rise Constructions Ltd | Construction | 2023 |
| Majestic Roofcare Ltd | Construction | 2025 |
| Makaita Limited | Health & social care | 2014 |
| Makes IT Effortless Ltd | Information & communication | 2024 |
| Malbar Homes Limited | Households | 2025 |
| Malcontent Ltd | Information & communication | 2015 |
| Malden Property Maintenance Limited | Construction | 2015 |
| Malik Tech Consulting Ltd | Information & communication | 2026 |
| Malkier Ltd | Real estate | 2020 |
| Mallard Advisory Limited | Professional & scientific | 2025 |
| Malvarosa (Surbiton) Residents Association Limited | Households | 1971 |
| Malvern Court Freehold Limited | Real estate | 2025 |
| Malvern Solutions Limited | Professional & scientific | 2015 |
| MAN and Van Epsom Downs Limited | Transport & logistics | 2018 |
| Mana Kaha Ltd | Wholesale & retail | 2020 |
| Manas Studio Ltd | Arts & recreation | 1992 |
| Manders Consultancy Limited | Professional & scientific | 2015 |
| Maney Investments Limited | Real estate | 2018 |
| Manic Limited | Arts & recreation | 2000 |
| Manorgate Residents Association Limited | Households | 1962 |
| Manro Medical Ltd | Professional & scientific | 2011 |
| Manro Medical Practices LLP | | 2021 |
| Mansh Solutions Ltd | Information & communication | 2026 |
| Mansukh Mistry Ltd | Wholesale & retail | 2013 |
| Mantra Information Security Ltd | Information & communication | 2023 |
| Manuplus Ltd | Information & communication | 2009 |
| MAP and Compass Ltd | Administrative & support | 2023 |
| Maple Growth Management Limited | Administrative & support | 2008 |
| Maple Hill Partners Ltd | Wholesale & retail | 2008 |
| Maple House Residents Association Limited | Households | 1958 |
| Maple Leaf House (Surbiton) Management Company Limited | Households | 2014 |
| Maple Road 1854 Management Company Limited | Households | 2002 |
| Maple Roofing Ltd | Construction | 2020 |
| Maple Tree Mortgages Ltd | Financial services | 2024 |
| Maple Works Limited | Other services | 2013 |
| Maplewood Grove Limited | Real estate | 2024 |
| Mara Trading Ltd | Wholesale & retail | 2017 |
| Marefat Food Trading Ltd | Hospitality | 2018 |
| Marfoods UK Ltd | Wholesale & retail | 2013 |
| Margot Management Company Limited | Households | 1994 |
| Marguery Limited | Health & social care | 2021 |
| Marielle 24/7 Healthcare Services Ltd | Health & social care | 2022 |
| Marielle Compassionate Care Ltd | Health & social care | 2023 |
| Marielle Healthcare Consultancy Ltd | Health & social care | 2023 |
| Marielle Recruitment Ltd | Professional & scientific | 2023 |
| Marify Ltd | Professional & scientific | 2023 |
| Marine Debt Management Limited | Administrative & support | 1995 |
| Marinela Properties Ltd | Real estate | 2023 |
| Mariner International (UK) Limited | Professional & scientific | 1992 |
| Mariner International Travel (UK) Limited | Administrative & support | 1976 |
| Marinus Estates Limited | Real estate | 2025 |
| Marios Property Investments Ltd | Real estate | 2025 |
| Mark Morris Writing Solutions Ltd | Education | 2024 |
| Market Stall Limited | Hospitality | 2021 |
| Marketing 7 Ltd | Households | 2019 |
| Marlborough Gardens (Centre (Surbiton) Residents Association Limited | Households | 1962 |
| Marncrest Freehold Limited | Households | 2023 |
| Mars Ventures Limited | Information & communication | 2017 |
| Martinarts Limited | Arts & recreation | 2015 |
| Martini 247 Ltd | Real estate | 2025 |
| Maruzzella Restaurant Limited | Hospitality | 2024 |
| Marwilb Consulting Ltd | Professional & scientific | 2023 |
| Mary Elizabeth Wellness Ltd | Health & social care | 2025 |
| Marzoppi Properties International Ltd | Real estate | 2022 |
| Masaniello Spacca Limited | Hospitality | 2017 |
| Masefield Court (Surbiton) Maintenance Association Limited | Households | 1962 |
| Masonmark Constructors Limited | Construction | 2024 |
| Massage Beauty Spa Ltd | Health & social care | 2013 |
| Massala Corner Ltd | Hospitality | 2025 |
| Master of ANY Trade Ltd | Construction | 2017 |
| Master Tech Motors Ltd | Wholesale & retail | 2017 |
| Matapan Ltd | Real estate | 2025 |
| Matchbox Maintenance Ltd | Real estate | 2026 |
| Mathisys Trading Limited | Financial services | 2023 |
| Matt Gray Ltd | Professional & scientific | 2013 |
| Matthew Bacon Limited | Administrative & support | 2005 |
| Matthew Cowan Consulting Limited | Professional & scientific | 2012 |
| Matthew James Estate Agents Limited | Real estate | 2003 |
| Matthew Matthews Holdings Limited | Real estate | 2020 |
| Matusadona Limited | Professional & scientific | 2024 |
| Mauli Investment Ltd | Real estate | 2020 |
| Maureen Solutions Company Limited | Health & social care | 2014 |
| MAX Granti & Marble Tops Ltd | Construction | 2013 |
| MAX Plus Trading Ltd | Hospitality | 2025 |
| Maxhard Ltd | Construction | 2010 |
| Maximillan Limited | Wholesale & retail | 2019 |
| Maximise Your Earnings Ltd | Professional & scientific | 2023 |
| Maxine Robertson Management Limited | Arts & recreation | 2006 |
| Maxx Meridian Limited | Hospitality | 2013 |
| Maya Nails Ltd | Other services | 2026 |
| Mayas Kerala Kitchen Ltd | Hospitality | 2022 |
| Mayba Marketing Ltd | Professional & scientific | 2024 |