| Metal Masterpieces Limited | Manufacturing | 2024 |
| Meyer Brothers Ltd | Construction | 2023 |
| Meyson Properties Ltd. | Real estate | 2019 |
| MG Anfield Limited | Real estate | 2015 |
| MG Manchester Ltd | Real estate | 2016 |
| MGM & Group Limited | Construction | 2017 |
| MI Data Solutions Limited | Information & communication | 1996 |
| Michael J Hart Carpentry Limited | Construction | 2013 |
| Midlands UK Ltd | Construction | 2008 |
| MII LOK Limited | Hospitality | 2024 |
| Mill Huts Ltd | Real estate | 2020 |
| Miller Products Ltd | Other services | 2025 |
| Milliner House RTM Company Ltd | Real estate | 2021 |
| Mills Plastering Limited | Construction | 2025 |
| Millstream Management Services Limited | Financial services | 2022 |
| Millstream Motor Services Limited | Wholesale & retail | 2019 |
| Millwards Flooring Ltd | Wholesale & retail | 2024 |
| Mimi Consulting Ltd | Professional & scientific | 2020 |
| Mindology Marketing Ltd | Professional & scientific | 2021 |
| Minerva House RTM Company Limited | Households | 2009 |
| Mintcoaches Ltd | Transport & logistics | 2007 |
| Mintro Group Ltd | Real estate | 2025 |
| Mirage Management Company (Sandbanks) Limited | Households | 2005 |
| Mjhr Limited | Real estate | 2018 |
| MK Roofing Group Limited | Construction | 2016 |
| MLL Consultancy Ltd. | Administrative & support | 2016 |
| Mlrsg Limited | Construction | 2012 |
| Mluk Investments Limited | Financial services | 2021 |
| Mmit Limited | Information & communication | 2008 |
| Modo Homes Ltd | Real estate | 2023 |
| Modular Coatings Limited | Manufacturing | 1983 |
| Mollys Castle Ltd | Real estate | 2022 |
| Molyneux Flats Limited | Real estate | 2017 |
| Momentum Motorsports Ltd | Professional & scientific | 2026 |
| Momoh Ventures Limited | Real estate | 2024 |
| Montana Rose Leisure Ltd | Hospitality | 2015 |
| Montare Studio Limited | Professional & scientific | 2022 |
| Moody RUM Ltd | Manufacturing | 2020 |
| Moonfleet Compass Freehold Company Ltd | Real estate | 2025 |
| Moonstone Crystals Ltd | Wholesale & retail | 2022 |
| Moorhouse Architecture Limited | Professional & scientific | 2014 |
| Moortown Farms Limited | Agriculture & fishing | 1946 |
| Moralee Management Co Limited | Households | 2024 |
| Morant Cottages Residents' Company Limited | Households | 2002 |
| More on Top Ltd | Wholesale & retail | 2026 |
| Moredem Limited | Wholesale & retail | 2005 |
| MORTGAGE4YOU Ltd | Financial services | 2000 |
| Mortgageanalytics Ltd | Administrative & support | 2018 |
| Mortgages for Medics Ltd. | Financial services | 2014 |
| Mossman Heating Ltd | Construction | 2025 |
| Motion Graphic Design Limited | Arts & recreation | 2009 |
| Motorbike Storage Ltd | Transport & logistics | 2016 |
| Mouland Haulage Limited | Transport & logistics | 2000 |
| Movate UK Limited | Information & communication | 2001 |
| Moveitto Ltd | Transport & logistics | 2026 |
| Moveto Events Limited | Administrative & support | 2025 |
| Moveto Residential Limited | Information & communication | 2025 |
| Moving Cloud Marketing Services Ltd | Professional & scientific | 2022 |
| Moyles Court School Limited | Education | 2010 |
| MR Matthew Baker Ltd | Health & social care | 2025 |
| MRH Sport Ltd | Wholesale & retail | 2023 |
| MTB Site Services Ltd | Construction | 2018 |
| MTL Investments Ltd | Financial services | 2026 |
| MTN Compliance Ltd | Administrative & support | 2019 |
| Mulberry Grounds Limited | Real estate | 2018 |
| Multi-Let Area Two Limited | Real estate | 2015 |
| Multi-Let Birmingham Limited | Real estate | 2017 |
| Multi-Let Head Office Limited | Professional & scientific | 2015 |
| Multi-Let Limited | Real estate | 2013 |
| Murano South Ltd | Hospitality | 2023 |
| Murdoch Family Ltd | Health & social care | 2014 |
| Mutual Solutions Limited | Professional & scientific | 2007 |
| My Ambition Properties Limited | Real estate | 2020 |
| My Ambition Services Limited | Administrative & support | 2021 |
| My Digital Reading Diary Ltd | Education | 2024 |
| My Integrity Limited | Extraterritorial | 2023 |
| My Investment Limited | Extraterritorial | 2023 |
| My Slcn CIC | Information & communication | 2025 |
| Myambition Limited | Administrative & support | 2006 |
| Mycelial Consulting Limited | Information & communication | 2019 |
| Mylor Carpentry Ltd | Construction | 2020 |
| Mystery Arts Limited | Wholesale & retail | 1994 |
| Mywave App Ltd | Professional & scientific | 2019 |
| N a Property South Limited | Real estate | 2021 |
| Nailpro and Beauty Ringwood Limited | Other services | 2024 |
| Namci IT Ltd. | Information & communication | 2019 |
| NAN Clach Extension Limited | Construction | 2020 |
| Nance Maccabe Limited | Financial services | 2012 |
| Naomie Thompson Ltd | Other services | 2022 |
| Napier Electrical Ltd | Construction | 2021 |
| Narrative Branding Group Ltd | Professional & scientific | 2024 |
| National Drainage Services Ltd | Professional & scientific | 2026 |
| Natives Online Limited | Professional & scientific | 2008 |
| Natural Healing Dorset Ltd | Health & social care | 2021 |
| Natural Healing Studio Ltd | Health & social care | 2025 |
| Nautisole Ltd | Wholesale & retail | 2022 |
| NDK Holdings Ltd | Financial services | 2016 |
| Nectar & Ambrosia Foods Ltd | Wholesale & retail | 2019 |
| Needr Ltd | Information & communication | 2026 |
| Nemesis Pest Control Ltd | Health & social care | 2007 |