| Modern Barber Shop Ltd | Other services | 2023 |
| Modern Entrances Ltd | Construction | 2024 |
| Modern Heating & Cooling Ltd | Construction | 2011 |
| Modern Heroes Car Sales Ltd | Wholesale & retail | 2024 |
| Modglaze Ltd | Construction | 2026 |
| Modified Mercs Limited | Wholesale & retail | 2023 |
| Modify Spaces Ltd | Construction | 2023 |
| Modo Design Ltd. | Professional & scientific | 2024 |
| Modo Planning Ltd | Professional & scientific | 2025 |
| Module Interiors Limited | Construction | 2021 |
| Modus FT Limited | Manufacturing | 2013 |
| Mohamed and Associate Limited | Health & social care | 2006 |
| Mohamed Barrie GL Food Delivery Services Ltd | Hospitality | 2025 |
| Mohawk Tyres (U.K.) Limited | Professional & scientific | 1978 |
| Moin Motors Ltd | Wholesale & retail | 2022 |
| Molyneux Pickford Associates Limited | Professional & scientific | 2019 |
| MOM SEO Ltd | Professional & scientific | 2025 |
| Momentum Pole & Aerial Ltd | Arts & recreation | 2018 |
| Monabs Limited | Wholesale & retail | 2025 |
| Monarch Embassy Ltd | Wholesale & retail | 2021 |
| Monarchy Homes Ltd | Real estate | 2024 |
| Monavale Limited | Health & social care | 2020 |
| Monde Business Solutions Ltd | Administrative & support | 2025 |
| Monena Properties Ltd | Real estate | 2020 |
| Monere Construction Limited | Construction | 1998 |
| Monest Accounts Limited | Professional & scientific | 2013 |
| Money Fitness Accounting Ltd | Professional & scientific | 2025 |
| Money Fitness Expert Limited | Education | 2023 |
| Moni Accounts Ltd | Professional & scientific | 2025 |
| Monkey Bar Events Ltd | Hospitality | 2020 |
| Monkey Puzzle Software Ltd | Information & communication | 2025 |
| Monksfield Homes Limited | Construction | 2020 |
| Monoceros Properties Ltd | Construction | 2024 |
| Monochrome Lets Ltd | Real estate | 2025 |
| Monogate Limited | Administrative & support | 2002 |
| Monster MIX Limited | Manufacturing | 2019 |
| Monster Surveys Ltd | Construction | 2016 |
| Monster-Removals Ltd | Water & waste | 2021 |
| Monster.Inks Tattoo (Uk-Inks) Ltd | Arts & recreation | 2025 |
| Montagu Academy Sports and Education Services Ltd | Arts & recreation | 2018 |
| Montanas Group Ltd | Information & communication | 2019 |
| Montec Ventures Ltd | Real estate | 2021 |
| Montem Road Limited | Households | 2017 |
| Montessori Alternative Provision Limited | Education | 2025 |
| Montgomery House Holdings Limited | Financial services | 2023 |
| Montpellier Hair Limited | Other services | 2021 |
| Montpellier Lodge Limited | Administrative & support | 2018 |
| Montpellier Terrace Residents Management Limited | Households | 2023 |
| Montrose Graham Holdings Limited | Financial services | 2025 |
| Montrose Law Ltd | Professional & scientific | 2025 |
| Monty Resourcing Limited | Health & social care | 2023 |
| Moodmoves Ltd | Professional & scientific | 2014 |
| Moolla Marketing Ltd | Information & communication | 2025 |
| Moore Mortgages & Financial Services Ltd | Financial services | 2014 |
| Moorend Limited | Manufacturing | 2013 |
| Moorend Motor Company Limited | Wholesale & retail | 2023 |
| Moorlea Management Ltd | Real estate | 2025 |
| Moose Partnership Limited | Professional & scientific | 2002 |
| Moot Point Consulting Limited | Information & communication | 2012 |
| Morants Limited | Administrative & support | 2025 |
| More Homes Bromley LLP | | 2016 |
| More Homes Waltham Forest LLP | | 2018 |
| Moreton C.Cullimore and Son,Limited | Transport & logistics | 1965 |
| Moreton C.Cullimore(Gravels)Limited | Mining & quarrying | 1943 |
| Moreton Cullimore Holdings Limited | Financial services | 2025 |
| Moreton Edwards Associates Architects Ltd | Professional & scientific | 2020 |
| Morg Property Limited | Real estate | 2016 |
| Morgan Consulting Tewkesbury Ltd | Professional & scientific | 2012 |
| Morgan Devere Corporate Finance UK Limited | Financial services | 2017 |
| Morgan Devere Menswear Cheltenham Ltd | Wholesale & retail | 2022 |
| Morgan Devere Menswear Ltd | Wholesale & retail | 2016 |
| Morgan Gloucester Group Limited | Financial services | 2022 |
| Morgan Gloucester Properties Limited | Real estate | 2022 |
| Morgan Habitare Limited | Real estate | 2019 |
| Morgan's Business Solutions Ltd | Professional & scientific | 2005 |
| Morgan's Holdings Group Limited | Financial services | 2024 |
| Morlader Properties Ltd | Real estate | 2017 |
| Morning Star Accounting Services Limited | Professional & scientific | 2011 |
| Morningstonerose Limited | Construction | 2024 |
| Morosanca Ltd | Administrative & support | 2025 |
| Morris Lecturing Limited | Education | 2025 |
| Morroway House Community Interest Company | Real estate | 2019 |
| Mortgage Hub Expert Limited | Financial services | 2018 |
| Mortgage Train Academy Ltd | Education | 2026 |
| Mortise Project Management Limited | Professional & scientific | 2024 |
| Morton Products Limited | Administrative & support | 2005 |
| Mosern Healthcare Recruitment Ltd | Administrative & support | 2022 |
| Mosh Media & Events Limited | Manufacturing | 2025 |
| Moss & SON Ltd | Agriculture & fishing | 2005 |
| Mossline Services Limited | Information & communication | 2025 |
| Mossva Ltd | Wholesale & retail | 2025 |
| Most Valued Player Ltd | Professional & scientific | 2024 |
| Motala & Sons Ltd | Wholesale & retail | 2008 |
| Motorhome Medics Limited | Wholesale & retail | 2012 |
| Motorslink Limited | Wholesale & retail | 2015 |
| Mottram Property Limited | Real estate | 2025 |
| Mouder Ltd | Professional & scientific | 2025 |
| Mount Everest Property Ltd | Real estate | 2020 |
| Mountain Healthcare Properties Limited | Real estate | 2021 |
| Moutra Ltd | Health & social care | 2020 |