| MMT UK (PTY) Ltd | Information & communication | 2022 |
| MN Auto Service Ltd | Wholesale & retail | 2025 |
| MND Technomate Limited | Information & communication | 2024 |
| MNJ Planners Ltd | Administrative & support | 2026 |
| Mnmr Ltd | Transport & logistics | 2025 |
| MNN Global Investments Ltd | Wholesale & retail | 2016 |
| Moaiyk Limited | Hospitality | 2024 |
| Mobile Mechanic Swindon Ltd | Wholesale & retail | 2025 |
| Mobile Motoring Maintenance Limited | Wholesale & retail | 2003 |
| Mobile Tech Centre Limited | Wholesale & retail | 2019 |
| Mobility and General Suppliers / More Care First Ltd | Health & social care | 2012 |
| MOD Autos Limited | Wholesale & retail | 2009 |
| Modelzone Limited | Extraterritorial | 2013 |
| Moden Recruitment Limited | Administrative & support | 2024 |
| Modern Fashion Solutions Limited | Wholesale & retail | 2019 |
| Moderncuts Barbers Ltd | Other services | 2023 |
| Modify Medical Services Limited | Professional & scientific | 2015 |
| Modtex Interiors Limited | Construction | 1993 |
| Moethus Abertawe Limited | Real estate | 2021 |
| Moethus Gwyr Ltd | Real estate | 2020 |
| Moga Construction Services Limited | Construction | 2021 |
| Mogi Consultancy Limited | Wholesale & retail | 2018 |
| Mohcute Care World Ltd | Health & social care | 2022 |
| Mohcute International Ltd | Professional & scientific | 2022 |
| Mohsen New Tech Limited | Professional & scientific | 2023 |
| Mojo Health Limited | Health & social care | 2026 |
| Moldavite Manor Ltd | Wholesale & retail | 2024 |
| Molren Agency Ltd | Professional & scientific | 2022 |
| Momo Catering Limited | Hospitality | 2025 |
| Monahans Limited | Professional & scientific | 1995 |
| Monahans Professional Services Limited | Financial services | 2022 |
| Monahans Trustees Limited | Professional & scientific | 2012 |
| Monai Global Ltd | Information & communication | 2025 |
| Monarch Capital Advisory Ltd | Professional & scientific | 2026 |
| Monarch Roofing Co Limited | Construction | 2001 |
| Monga Yakare (M.Y) U.K Limited | Wholesale & retail | 2023 |
| Mongoose Publishing Limited | Information & communication | 2002 |
| Monica's Properties Development Ltd | Real estate | 2025 |
| Monika Cleaning Service Limited | Administrative & support | 2025 |
| Monitor Intelligence Services Ltd | Information & communication | 2011 |
| Monkey Property Limited | Real estate | 2025 |
| Monkstone Bay (Saundersfoot) Management Company Ltd | Households | 2017 |
| Monocle Properties Limited | Real estate | 2025 |
| Monolo Global Limited | Hospitality | 2025 |
| Monologic Ltd | Information & communication | 2019 |
| Montane Construction Ltd | Construction | 2026 |
| Montano Limited | Wholesale & retail | 2016 |
| Monteja Consulting Limited | Information & communication | 2006 |
| Montgomery Faith Limited | Administrative & support | 2006 |
| Montoscar Enterprises Limited | Manufacturing | 2015 |
| Montpelier Joinery Ltd | Construction | 2014 |
| Montpellier Court (Gloucester) Management Limited | Real estate | 2004 |
| Montreux Developments Limited | Construction | 1981 |
| Montrose Engineering Limited | Professional & scientific | 2015 |
| Montwex PTY Ltd | Wholesale & retail | 2012 |
| Monument Promotions Limited | Administrative & support | 2017 |
| Monxton Place Residents Association (NO.2) Limited | Households | 2012 |
| Moon on a Stick Wellness Ltd | Health & social care | 2025 |
| Moon Star 165 Limited | Hospitality | 2023 |
| Mooney Building and Construction Services Limited | Construction | 2019 |
| Moonface Digital Limited | Information & communication | 2023 |
| Moonraker Canalboats Limited | Other services | 2009 |
| Moonstone a Limited | Real estate | 2024 |
| Moonstone Feminine Ltd | Wholesale & retail | 2023 |
| Moonstruck Productions Limited | Wholesale & retail | 2021 |
| Moore Property Group Ltd | Real estate | 2016 |
| Moos on Thames Limited | Wholesale & retail | 2022 |
| Moose Properties Limited | Real estate | 2004 |
| Moovahome Lettings Limited | Real estate | 2023 |
| Moovahome Limited | Real estate | 2013 |
| Moovahome Property Limited | Real estate | 2023 |
| Moovahome Rooms Limited | Real estate | 2019 |
| Mopheli Consultancy Limited | Professional & scientific | 2019 |
| Morcumb's Mortgage Services Ltd | Financial services | 2011 |
| More Property Solutions Ltd | Construction | 2022 |
| More Reasons to Ltd | Professional & scientific | 2011 |
| More Than a Mouthful Ltd | Hospitality | 2013 |
| More Than Mulch Ltd | Wholesale & retail | 2026 |
| Morecombe Transport Solutions Ltd | Transport & logistics | 2020 |
| Moredon PO Ltd | Wholesale & retail | 2025 |
| Moredon Stores KP Ltd | Wholesale & retail | 2025 |
| Moregen Ltd | Wholesale & retail | 2019 |
| Moreton Animal Therapy Limited | Administrative & support | 2010 |
| Morgan Sports Ltd | Wholesale & retail | 2025 |
| Morgan Wrona Limited | Construction | 2017 |
| Morland Carpentry & Building Services Limited | Manufacturing | 2017 |
| Morland Ceramics Limited | Construction | 2008 |
| Morley & Co (UK) Ltd | Professional & scientific | 2014 |
| Morley Electric Forecourt Ltd | Energy | 2020 |
| Morley Electrical Contractors Limited | Construction | 2013 |
| Mormac Services Ltd | Construction | 2023 |
| Moroccan Kitchen Sisters Ltd | Hospitality | 2025 |
| Moroccan Kitchen Swindon Ltd | Hospitality | 2026 |
| Moroz Transport Ltd | Transport & logistics | 2022 |
| Morp Limited | Transport & logistics | 2015 |
| Morphosys Consultants Limited | Professional & scientific | 2013 |
| Morris Owen Company Secretarial Limited | Extraterritorial | 2010 |
| Morris Owen Limited | Professional & scientific | 1998 |
| Morrison & Masters Limited | Professional & scientific | 1988 |
| Morrison Food and Wine Ltd | Wholesale & retail | 2018 |