| MI Partnership Limited | Hospitality | 2026 |
| Mi-Handyman Ltd | Construction | 2018 |
| Mian Brother London Limited | Construction | 2019 |
| MIC Ventures Limited | Professional & scientific | 1996 |
| Michael Everett & Company (Walton) Limited | Real estate | 2003 |
| Michael Everett and Company (Banstead) Limited | Real estate | 2004 |
| Michael Garnham Associates Ltd | Professional & scientific | 2013 |
| Michael Hill Architects Ltd | Professional & scientific | 2020 |
| Michael Lukey Plumbing Limited | Construction | 2004 |
| Michael Spector Consulting Ltd | Professional & scientific | 2024 |
| Michael Wise Cars Limited | Wholesale & retail | 2010 |
| MID Surrey Theatre Company | Arts & recreation | 2003 |
| Midanstef Limited | Transport & logistics | 2021 |
| Midsummer Place Management Company Limited | Households | 1998 |
| Mighty Quin Consulting Limited | Professional & scientific | 2014 |
| Milano Property Management Ltd | Households | 2026 |
| Mileglen Limited | | 1991 |
| Miles Warriner Limited | Professional & scientific | 2011 |
| Milev Ltd | Health & social care | 2011 |
| Milford Homes Ltd | Real estate | 2022 |
| Mill View (Ewell) Management Company Limited | Real estate | 1992 |
| Millais Crescent (Management Company) Limited | Households | 2003 |
| Millars Property Solutions Ltd | Real estate | 2026 |
| Millennium Chess Coaching Limited | Arts & recreation | 2003 |
| Milznmitz Ltd | Real estate | 2018 |
| Mimo Catering Ltd | Hospitality | 2025 |
| Minconsult Limited | Professional & scientific | 2012 |
| Mind Sprout Ltd | Manufacturing | 2026 |
| Mind-Growth Mastery CIC | Health & social care | 2019 |
| Mindful Breeze Ltd | Real estate | 2024 |
| Minesh Patel Dentistry Ltd | Health & social care | 2010 |
| Ming Party Hire Ltd | Hospitality | 2025 |
| Minipan UK Ltd | Professional & scientific | 2025 |
| Minnett Scaffolding Ltd | Construction | 2021 |
| Mint Property (Kingswood) Limited | Real estate | 2021 |
| Mint Spices Limited | Hospitality | 2022 |
| Minto Properties Ltd | Real estate | 2018 |
| Mintwater Close Residents Association Limited | Households | 2021 |
| Mipod Interiors Limited | Manufacturing | 2009 |
| Miradel Investment Company Limited | Real estate | 1999 |
| Miralet Investment Ltd | Real estate | 2025 |
| Mirus Investments Ltd | Real estate | 2018 |
| Mish Accountants Ltd | Professional & scientific | 2026 |
| Miss Central Heating Ltd | Construction | 2021 |
| Miss M Skyers Limited | Professional & scientific | 2013 |
| Misshaped Music Limited | Information & communication | 2021 |
| Mistley Court Limited | Households | 1957 |
| Mitre Court (Purley) Management Company Ltd | Households | 2011 |
| Mitre Financial Limited | Professional & scientific | 1997 |
| Mitzvah Ltd | Households | 2022 |
| Miwe Michael Wenz UK Ltd | Professional & scientific | 2025 |
| MIX Smiths Bars & Beverages Limited | Wholesale & retail | 2023 |
| Mizzi Business & Media Limited | Professional & scientific | 2017 |
| MJA Accountants Limited | Professional & scientific | 2015 |
| MJA Investments Limited | Real estate | 1991 |
| MJM Analysis Limited | Administrative & support | 2014 |
| Mjrj Ltd | Real estate | 2024 |
| MJS Energy Solutions Ltd | Construction | 2025 |
| MK Living Ltd | Construction | 2025 |
| MK Pest Defence Ltd | Administrative & support | 2026 |
| MKU Consulting Services Ltd | Real estate | 2010 |
| ML Rolling Stock Solutions Ltd | Professional & scientific | 2025 |
| Mlkg Holdings Limited | Real estate | 2016 |
| MLR Security Limited | Construction | 2025 |
| MM Facilities Management Limited | Professional & scientific | 2022 |
| MM Sport OFF SZN Ltd | Arts & recreation | 2025 |
| MMC Roofing Limited | Construction | 2023 |
| Mmjh Limited | Administrative & support | 2015 |
| MMY Consultants Limited | Construction | 2001 |
| Mnbg Limited | Professional & scientific | 2025 |
| Mo-Ichido England Ltd | Education | 2022 |
| Moater Group Limited | Financial services | 2026 |
| Mobile Path Ltd | Information & communication | 2012 |
| Mobile Screen Ltd | Administrative & support | 2016 |
| Mobius Partners Limited | Professional & scientific | 2012 |
| Mod-Stock Exhaust Modifications Ltd | Wholesale & retail | 2020 |
| Model Systems (London) Limited | Professional & scientific | 2003 |
| Modistika Ltd | Wholesale & retail | 2024 |
| Modular Mechanical Services Limited | Construction | 2024 |
| Moet Construction Ltd | Construction | 2024 |
| Moggmoola Limited | Professional & scientific | 2017 |
| Moira Stuart Limited | Administrative & support | 2010 |
| Moji Media Ltd | Information & communication | 2015 |
| Mole Valley Designs Ltd | Professional & scientific | 2022 |
| Mole Valley Groundwork Ltd | Professional & scientific | 2018 |
| Moly Development Ltd | Real estate | 2022 |
| Monaci Consultancy Limited | Health & social care | 2010 |
| Monaco Services Limited | Professional & scientific | 2020 |
| Monarch Management Services Ltd | Real estate | 2025 |
| Monkey PMS Ltd | Professional & scientific | 2026 |
| Monro Employee Benefits Ltd | Administrative & support | 2022 |
| Monro Financial Management Ltd | Professional & scientific | 2014 |
| Monro Projects Ltd | Administrative & support | 2014 |
| Montague & Stone Holdings Limited | Construction | 2022 |
| Montague & Stone Limited | Construction | 2019 |
| Monteith Building Ltd | Construction | 2015 |
| Monty BOY Ltd | Professional & scientific | 2024 |
| Moody TOM Ltd | Extraterritorial | 2009 |
| Moola Melons Ltd | Wholesale & retail | 2020 |
| Moomoo Oasis Ltd | Wholesale & retail | 2023 |