| Mesoa Skincare Limited | Wholesale & retail | 2015 |
| Messy Treats Limited | Hospitality | 2018 |
| Metaform Resources L.P. | | 2018 |
| Mewn Cymeriad / in Character Ltd | Education | 2014 |
| Mexton Commerce PC | | 2019 |
| Miah Ventures Limited | Hospitality | 2016 |
| Micasa Homeware Limited | Wholesale & retail | 2025 |
| Microlux L.P. | | 2018 |
| Midas Management Limited | Administrative & support | 2025 |
| Mike Kirk Enterprises Limited | Wholesale & retail | 2000 |
| Mike's Scaffolding Limited | Construction | 2002 |
| Milkwell Ltd | Agriculture & fishing | 2013 |
| Mill Carpets & Flooring Limited | Wholesale & retail | 2006 |
| Mitchell's Plumbing Ltd | Construction | 2026 |
| Mitl CYF | Professional & scientific | 2023 |
| MJB Lighthouse Solutions Ltd | Information & communication | 2023 |
| Mobility Mapper Ltd | Information & communication | 2024 |
| Moduron Derwydd Motors CYF | Wholesale & retail | 2024 |
| Moffatt Properties Limited | Real estate | 2017 |
| Moilin CYF | Information & communication | 2012 |
| Molrae 25 Limited | Construction | 2017 |
| Moltân Ltd | Education | 2017 |
| Monkstone Ltd | Hospitality | 2025 |
| Monostar Ventures L.P. | | 2018 |
| Monroe's Diner and Takeaway Ltd | Hospitality | 2019 |
| Mooch ETC Ltd | Wholesale & retail | 2013 |
| MOR a Mynydd (Penrhyn) CYF | Hospitality | 2019 |
| MOR Tawel Consultancy Ltd | Professional & scientific | 2022 |
| Moreia Limited | Construction | 2022 |
| Morgan & Cuss Limited | Construction | 2016 |
| Morgan Automotive Ltd | Wholesale & retail | 2025 |
| Morgan Construction Limited | Extraterritorial | 2011 |
| Morgan Construction Wales Limited | Construction | 2003 |
| Morgan Developments Wales Limited | Construction | 2006 |
| Morgan Elis Limited | Professional & scientific | 2014 |
| Morgan Homes Limited | Real estate | 2011 |
| Morgan Properties and Lettings Ltd | Real estate | 2022 |
| Morgan Wealth Management Limited | Financial services | 2004 |
| Morgans Rees CYF | Real estate | 2026 |
| Moriox Technologies Ltd | Information & communication | 2023 |
| Morland (Llandeilo) Ltd | Real estate | 2025 |
| Morse Investments Limited | Real estate | 2024 |
| Mortlock Consulting Ltd | Professional & scientific | 2013 |
| Motion Chiropractic Ltd | Health & social care | 2022 |
| Motive Multi Media Ltd | Information & communication | 2025 |
| Movinci Ltd | Wholesale & retail | 2025 |
| Moving Pics Limited | Information & communication | 2013 |
| Mumford LOW Bake Centre Limited | Wholesale & retail | 2026 |
| Music to Remember Limited | Professional & scientific | 2015 |
| Mwdandhills Ltd | Manufacturing | 2025 |
| My Way Travel PC | | 2019 |
| MYHILL2 Properties Ltd | Real estate | 2021 |
| Myrddin Heritage Ltd | Agriculture & fishing | 2017 |
| N and a James Limited | Wholesale & retail | 1973 |
| N C R Homes Ltd | Real estate | 2025 |
| N J Landscapes (Wales) Ltd | Administrative & support | 2016 |
| N J Windley Construction Limited | Construction | 2020 |
| N R J Travel Limited | Transport & logistics | 2025 |
| Naaf Properties Ltd | Real estate | 2024 |
| Nant Helyg Services Limited | Hospitality | 2021 |
| Nant Property Limited | Real estate | 2020 |
| Nantcwmrhys Limited | Wholesale & retail | 2003 |
| Nantyci Consultancy Limited | Real estate | 1998 |
| Nash Avenue Properties Ltd | Construction | 2024 |
| National Engineering Limited | Manufacturing | 2022 |
| Nationcymru CYF | Information & communication | 2018 |
| Natural Wagyu Limited | Agriculture & fishing | 2014 |
| Nature's Best Catering Limited | Hospitality | 2017 |
| NCG (Hereford) Limited | Construction | 2017 |
| NE Logistics Ltd | Transport & logistics | 2026 |
| Neal James Plumbing & Heating Ltd | Construction | 2013 |
| Nelson Contract Services Limited | Transport & logistics | 2025 |
| Neurofocus Ltd | Other services | 2024 |
| Neville Davies Plant Hire Ltd | Administrative & support | 2019 |
| New China Taste Limited | Hospitality | 2020 |
| New ERA Scaffolding Services Ltd | Construction | 2026 |
| New Road Garage (Llandovery) Limited | Wholesale & retail | 2005 |
| Newbridge Steels Limited | Administrative & support | 2016 |
| Newport Fire & Security Ltd | Administrative & support | 2024 |
| Nexoria Insights Limited | Professional & scientific | 2025 |
| NG Carriers L.P. | | 2018 |
| Nigel Howells Consultancy Limited | Professional & scientific | 2013 |
| Nigel Jenkins Construction Ltd | Construction | 2011 |
| Niner Driving School Limited | Education | 2015 |
| Niwropatholeg Cymru CYF | Health & social care | 2023 |
| NKE Retailing Ltd | Transport & logistics | 2025 |
| NO Probs Productions Limited | Extraterritorial | 2001 |
| Nolan Upvc (Holdings) Limited | Manufacturing | 2020 |
| Nolan Upvc (Topco) Limited | Financial services | 2026 |
| Nolan Upvc Limited | Construction | 1990 |
| Non-Slip Coatings Limited | Wholesale & retail | 2025 |
| Noodle 101 Ltd | Hospitality | 2025 |
| Noodlesandmore Ltd | Hospitality | 2020 |
| Norlands Consulting Limited | Professional & scientific | 2015 |
| Notts Bar Ltd | Hospitality | 2016 |
| Notts Square Clinic Limited | Education | 2003 |
| Novotractis Care Service Ltd | Health & social care | 2025 |
| NSR Leisure Ltd | Wholesale & retail | 2023 |
| Nurture Magu CIC | Health & social care | 2018 |
| Nutriade Ltd | Wholesale & retail | 2021 |