| LUX Nails Welshpool Ltd | Other services | 2026 |
| Lymore Estate Limited | Real estate | 2024 |
| Lymore Estate Trustee Limited | Professional & scientific | 2024 |
| M & D Recycling Machinery Ltd | Professional & scientific | 2006 |
| M Cadwallader Limited | Professional & scientific | 2006 |
| M E Potter (Farms) Limited | Agriculture & fishing | 1997 |
| M P Canning Limited | Real estate | 2012 |
| M. E. & a. Hughes Limited | Manufacturing | 2011 |
| M.H. Engineering (Midlands) Limited | Manufacturing | 2001 |
| M.J. Fabrications (Wales) Limited | Construction | 2003 |
| Maes Y Wennol Management Company Ltd | Households | 2021 |
| Maesydd Biogas Limited | Extraterritorial | 2017 |
| MAG Mell Limited | Hospitality | 2025 |
| Maguire Aviation Ltd | Administrative & support | 2022 |
| Maguire Contracting Limited | Construction | 2015 |
| Maguire Park Holdings Ltd | Hospitality | 2022 |
| Maguire Park Management Ltd | Hospitality | 2022 |
| Maguires Developments Limited | Households | 2017 |
| Malbay Homes Limited | Construction | 1997 |
| Mansell Concreting Ltd | Construction | 2017 |
| Marcella Management LLP | | 2015 |
| Margaret Bardsley Outside the Box Ltd | Professional & scientific | 2014 |
| Marian Food and Catering Ltd | Hospitality | 2026 |
| Mark W Hudson Design Limited | Information & communication | 2021 |
| Marton Machinery & Plant Ltd | Administrative & support | 2026 |
| Mave Consulting Ltd | Professional & scientific | 2009 |
| Mavis Kebab Ltd | Hospitality | 2023 |
| Maylor Properties Limited | Real estate | 1961 |
| MCP Services Limited | Professional & scientific | 2015 |
| Mentore Limited | Professional & scientific | 1993 |
| Metals & Alloys (INT) PLC | Professional & scientific | 1996 |
| Metis Point Limited | Professional & scientific | 2026 |
| MID Wales Country Escapes Ltd | Hospitality | 2022 |
| MID Wales Fayres Limited | Manufacturing | 2003 |
| MID Wales Recruitment Limited | Administrative & support | 2025 |
| MID Wales Renewables Limited | Agriculture & fishing | 2015 |
| MID Wales Sign and Print Limited | Manufacturing | 2020 |
| MID Wales Vapes Limited | Wholesale & retail | 2025 |
| Midwinter Academy of Performing Arts Ltd | Arts & recreation | 2021 |
| Mike Pearce Independent Financial Adviser Ltd | Financial services | 2018 |
| Mike Vaughan Properties Limited | Real estate | 1996 |
| Mills Poultry Limited | Agriculture & fishing | 2002 |
| Milne Installations Ltd | Extraterritorial | 2016 |
| Minafon Ltd | Hospitality | 2022 |
| Mobilespace Ltd | Wholesale & retail | 2025 |
| Montgomery Property Improvements Ltd | Construction | 2016 |
| Montgomeryshire Homes Limited | Construction | 2014 |
| Montgomeryshire Wildlife Trust Limited | Other services | 1982 |
| Monty Glazing Limited | Construction | 2023 |
| Monty MIX Ltd | Manufacturing | 2023 |
| Montychini Investments Limited | Hospitality | 2006 |
| Mooguroo CYF | Arts & recreation | 2024 |
| Moreva Limited | Professional & scientific | 2022 |
| Morris Plant Hire Limited | Construction | 2003 |
| Morrison Marine Limited | Construction | 2022 |
| Motorsport Services Limited | Arts & recreation | 2015 |
| Motosafe Innovations Ltd | Wholesale & retail | 2021 |
| Mount Bamboo Limited | Hospitality | 2023 |
| MOVE365 Ltd | Arts & recreation | 2026 |
| MTS Brands Ltd. | Wholesale & retail | 2013 |
| Mulberry Business Link Ltd | Extraterritorial | 2004 |
| MW Stands Limited | Manufacturing | 2025 |
| MWT Trading Limited | Other services | 2021 |
| My Sempa Ltd | Administrative & support | 2024 |
| Mytown Media Limited | Information & communication | 2012 |
| N C Holdings (Welshpool) Limited | Professional & scientific | 2008 |
| Natalka Shop Ltd | Wholesale & retail | 2024 |
| NET Carbon Limited | Professional & scientific | 2020 |
| Newmor Group Limited | Manufacturing | 2000 |
| Newmor Limited | Wholesale & retail | 2000 |
| NIS-SPEC1ST Limited | Wholesale & retail | 2012 |
| Nmetalsolutions Ltd | Manufacturing | 2025 |
| NO Snagz Limited | Information & communication | 2014 |
| Nomadic Property Holdings Ltd | Real estate | 2025 |
| Nomadic Washrooms (Franchising) Ltd | Administrative & support | 2023 |
| Nomadic Washrooms (Sales) Ltd | Wholesale & retail | 2023 |
| Nomadic Washrooms Group Ltd | Financial services | 2023 |
| Nomadic Washrooms Ltd | Administrative & support | 2021 |
| NOODEV8 Ltd | Information & communication | 2025 |
| Notned Ltd | Information & communication | 2018 |
| NRG Direct Mail Ltd | Manufacturing | 2002 |
| Nutrition Associates Limited | Health & social care | 1998 |
| NW Hughes Limited | Professional & scientific | 2006 |
| Oaklands Glamping & Treehouse Ltd | Hospitality | 2016 |
| Oakwood Manor Holdings Limited | Financial services | 2026 |
| Oakwood Manor Meats Ltd | Wholesale & retail | 2020 |
| Obot.Pm Ltd | Information & communication | 2018 |
| Offa's Dyke Properties Limited | Financial services | 2023 |
| Olivia and Stone Limited | Manufacturing | 2021 |
| Origin Analytical Ltd | Professional & scientific | 2010 |
| Outdoor Guerrilla Limited | Manufacturing | 2020 |
| Outlook Consulting Limited | Professional & scientific | 2017 |
| Owens Agricultural Limited | Agriculture & fishing | 2023 |
| Owens Civil Engineering Limited | Construction | 2016 |
| P & L Finance Limited | Financial services | 2015 |
| P Chapman Ltd | Professional & scientific | 2025 |
| P T Williams Building Contractors Ltd | Construction | 2008 |
| P.A.J. Developments Ltd | Construction | 2009 |
| Paddock Electrical Ltd | Construction | 2003 |
| Pandy Butchers Limited | Wholesale & retail | 2019 |