| Miller Howe on the Lake Limited | Hospitality | 2018 |
| Miller Used Office Furniture Limited | Wholesale & retail | 2022 |
| Miller-Brown Consulting Limited | Hospitality | 2021 |
| Millglade Consultancy Limited | Professional & scientific | 2008 |
| Mills & Ripley Limited | Administrative & support | 1997 |
| Millswing Limited | Households | 1985 |
| Milney Property Limited | Real estate | 2020 |
| Milzee.Pt&Sportsnutrition Ltd | Arts & recreation | 2025 |
| Minal Properties Ltd | Real estate | 2025 |
| Mind Body and SUE Ltd | Health & social care | 2021 |
| Mind Enquire Ltd | Other services | 2023 |
| Mind Thrive Wellbeing CIC | Education | 2026 |
| Mindhouse Limited | Real estate | 2025 |
| Mindjump Limited | Information & communication | 2023 |
| Mindspire Limited | Professional & scientific | 2018 |
| Ming's Beauty & Nail Salon Limited | Other services | 2021 |
| Mini Industries Ltd | Wholesale & retail | 2020 |
| Miniature Horse of the Year Show (Mhoys) Limited | Administrative & support | 2008 |
| Minksoda Ltd | Real estate | 2018 |
| Mino Carpentry & Joinery Ltd | Manufacturing | 2025 |
| Mint DJ Services Limited | Arts & recreation | 2018 |
| Mint UX Limited | Professional & scientific | 2025 |
| Miramedia Limited | Information & communication | 1999 |
| Mise EN Place Online Ltd | Information & communication | 2018 |
| Mise EN Scene Limited Partnership | | 2018 |
| Mister Chef Tunbridge Wells Limited | Hospitality | 2022 |
| Mitrâ Strategy Limited | Professional & scientific | 2019 |
| MJ Human Resources Limited | Other services | 2025 |
| MJK & TCK Investments LLP | | 2007 |
| MJL Accountancy Limited | Professional & scientific | 2023 |
| MJP Translations Ltd | Professional & scientific | 2021 |
| MJW IT Solutions Ltd | Information & communication | 2025 |
| MK HO Ltd | Hospitality | 2022 |
| MKM Investment Properties Ltd | Real estate | 2019 |
| ML Carpentry and Sons Limited | Manufacturing | 2014 |
| MLB Digital Limited | Information & communication | 2025 |
| Mlem Blep Ltd | Information & communication | 2024 |
| MLG Creative Ltd | Professional & scientific | 2017 |
| MLM Motor Trade Consultancy Ltd | Professional & scientific | 2023 |
| MLR Associates Limited | Administrative & support | 2012 |
| MMA Surveyors Limited | Professional & scientific | 2013 |
| MMH Property (BTL) Limited | Real estate | 2025 |
| MMH Property Limited | Construction | 2009 |
| Mmkb International Ltd | Professional & scientific | 2026 |
| Mmxx (Properties) LLP | | 2022 |
| MN Property Consultants Ltd | Professional & scientific | 2011 |
| MN Property Investments Limited | Real estate | 2019 |
| MNT Consulting Ltd | Professional & scientific | 2026 |
| MO Group Ltd | Professional & scientific | 2015 |
| Moar Performance Limited | Information & communication | 2015 |
| Moatlands Farm Limited | Agriculture & fishing | 1977 |
| Mobi Software Solutions Limited | Information & communication | 2012 |
| Mobility Sport International Limited | Wholesale & retail | 2020 |
| Mobilus Labs Limited | Manufacturing | 2017 |
| Mobiustudio Ltd | Professional & scientific | 2025 |
| Mocketts Cafe Ltd | Hospitality | 2023 |
| Modern Hues Decorating Co. Ltd | Construction | 2025 |
| Moffat Homes Ltd | Real estate | 2024 |
| Mogulprivateoffice Limited | Construction | 2018 |
| Mogulvision Limited | Information & communication | 2019 |
| Mohikauk Ltd | Real estate | 2024 |
| Mokkato Ltd | Wholesale & retail | 2024 |
| Molior Homes Limited | Construction | 2009 |
| Molyneux Advanced Systems Limited | Professional & scientific | 2014 |
| Molyneux Park and Somerville Gardens Owners Association Limited | Households | 1967 |
| Momac Energy Limited | Real estate | 2013 |
| Momentum Care Ltd | Health & social care | 2023 |
| Momentum Marketing Limited | Professional & scientific | 2026 |
| Monac Consulting Ltd | Information & communication | 2026 |
| Monceau Limited | Professional & scientific | 2014 |
| Mondo Events Ltd | Arts & recreation | 2026 |
| Monika Kozlowska Coaching Limited | Other services | 2020 |
| Moninski Consulting Ltd | Professional & scientific | 2018 |
| Monk Mind Disposal Ltd | Water & waste | 2025 |
| Monkey LOU Limited | Information & communication | 2008 |
| Monroe House RTM Limited | Households | 2015 |
| Monson Homes Limited | Construction | 2006 |
| Monson Road Holdings Ltd | Financial services | 2023 |
| Montacute Gardens Limited | Households | 2010 |
| Montacute Properties Limited | Households | 1996 |
| Montanaro Brothers Property Limited | Real estate | 2024 |
| Montanaro Business Services Ltd | Information & communication | 2024 |
| Montanaro Property Holdings Limited | Real estate | 2019 |
| Monteblu Property Services Limited | Real estate | 2016 |
| Montgomery Property Holdings Limited | Real estate | 2024 |
| Mood Cosmetics Ltd | Wholesale & retail | 2024 |
| Moon Maidens Limited | Manufacturing | 2024 |
| Moore Tailored Travel Ltd | Administrative & support | 2026 |
| Moose Labs Ltd | Information & communication | 2018 |
| Mopdev 2 Limited | Construction | 2025 |
| Morcos & Sons Limited | Real estate | 2024 |
| Morcos Enterprises LLP | | 2024 |
| Morescode Ltd | Information & communication | 2021 |
| Morris Engineering Projects Ltd | Professional & scientific | 2026 |
| Morrow Talent Ltd | Administrative & support | 2020 |
| Morse Studio Limited | Professional & scientific | 2008 |
| Mortgage Salad Limited | Financial services | 2006 |
| Mosaic Advisory Group Ltd | Professional & scientific | 2025 |
| Motah Ltd | Health & social care | 2023 |
| Mother Goose Estate Agency Ltd | Real estate | 2010 |