| Mcilhiney Property Ltd | Real estate | 2025 |
| MDD Bricklaying Limited | Construction | 2019 |
| Meadowlands Industrial Saws Ltd | Wholesale & retail | 2021 |
| Mellor Business Group Limited | Professional & scientific | 2011 |
| Melosson Limited | Information & communication | 2023 |
| Mercury Glass Limited | | 1983 |
| Merit Mortgage Solutions Ltd | Financial services | 2015 |
| MET Cabs Limited | Transport & logistics | 2007 |
| Meva 3 Ltd | Hospitality | 2026 |
| MIA Roberts Courier Ltd | Transport & logistics | 2025 |
| Michael Pearson Services Limited | Administrative & support | 2018 |
| Mivy Properties Ltd | Households | 2022 |
| MJ Perry Deco & Maintenance Ltd | Construction | 2022 |
| MJ Phillips Properties Ltd | Real estate | 2024 |
| MJD Asset Management Ltd | Households | 2020 |
| MJN Group Holdings Ltd | Financial services | 2025 |
| MJN Plant Hire Ltd | Administrative & support | 2018 |
| MJN Property Developments Ltd | Construction | 2018 |
| MJW Transport Services Ltd | Transport & logistics | 2024 |
| MMC Lifting Services Limited | Wholesale & retail | 2019 |
| Modathread Apparel Ltd | Wholesale & retail | 2026 |
| Morris Properties Ltd | Real estate | 2013 |
| Morrlec Limited | Other services | 2018 |
| Motowise Ltd | Wholesale & retail | 2023 |
| Mounteney Holdings Limited | Financial services | 2026 |
| Mountvale Estates Ltd | Real estate | 2019 |
| MRS M Ashraf Limited | Health & social care | 2013 |
| MSW Carbon Solutions Limited | Construction | 2013 |
| MTS (2025) Limited | Construction | 2026 |
| MW QS & Estimating Services Limited | Professional & scientific | 2017 |
| N Edwards Flooring Ltd | Construction | 2022 |
| Naagaa Retail Group Ltd | Wholesale & retail | 2025 |
| Naagaafuel Ltd | Wholesale & retail | 2021 |
| NAI Creative Studios Ltd | Professional & scientific | 2025 |
| Nation Mortgage & Finance Limited | Financial services | 2017 |
| Neil's Van Services Ltd | Transport & logistics | 2025 |
| New Simply Indian Limited | Hospitality | 2020 |
| Newport and Hereford Drainage Limited | Water & waste | 2012 |
| Nextgen Pathways Ltd | Health & social care | 2024 |
| Nic's Sewing Embroidery Print Ltd | Manufacturing | 2015 |
| Nightingale Medical Clinic Limited | Health & social care | 2021 |
| Nishna Homes Limited | Real estate | 2017 |
| Nordic Care (Holdings) Limited | Professional & scientific | 2011 |
| Nordic Care Services Ltd | Health & social care | 2002 |
| NRG Heating & Plumbing Services Limited | Construction | 2012 |
| Nuenergy Solutions Ltd | Other services | 2017 |
| NVS Property Management Limited | Real estate | 2019 |
| Oak Valley Joinery Ltd | Wholesale & retail | 2021 |
| Oakbourne Trading Limited | Professional & scientific | 2022 |
| Oakridge Direct Ltd. | Manufacturing | 1996 |
| Oliver’S Fabs Ltd | Professional & scientific | 2021 |
| OMS Group Limited | Wholesale & retail | 2011 |
| Optrain Group Ltd | Professional & scientific | 2024 |
| Optrain Limited | Professional & scientific | 2004 |
| Opus Facilities Management Ltd | Administrative & support | 2011 |
| Orbmetry Limited | Information & communication | 2025 |
| Oscar Palmerston Limited | Professional & scientific | 2021 |
| OSK Global Services Limited | Health & social care | 2020 |
| Outsource My HR Ltd | Administrative & support | 2023 |
| Overland Custom Conversions Ltd | Manufacturing | 2023 |
| P & P Change Management Ltd | Professional & scientific | 2022 |
| Palladium Promotions Limited | Arts & recreation | 1999 |
| Pallet Express South Wales Limited | Information & communication | 2001 |
| Park Home Solutions Ltd | Administrative & support | 2024 |
| Parker Motors (Tredegar) Limited | Wholesale & retail | 2010 |
| Party Harder Tours Ltd | Administrative & support | 2023 |
| Paul Phillips Carpentry Limited | Construction | 2017 |
| PCS & JPS Holdings Ltd | Information & communication | 2018 |
| Pegasus Heating Limited | Manufacturing | 2006 |
| Pendragon Security and Events Ltd | Administrative & support | 2025 |
| Phillips Building Company Tredegar Limited | Real estate | 2013 |
| Phillips Family Investments Limited | Financial services | 2024 |
| Pinnacle Carpentry Limited | Construction | 2017 |
| PJ Aberdare Ltd | Hospitality | 2019 |
| PL Brickwork Limited | Construction | 2020 |
| Planet Fitness Limited | Arts & recreation | 2024 |
| PNR Group Holdings Ltd | Financial services | 2022 |
| Pobl Bach South Wales C.I.C. | Education | 2017 |
| Polyfarma Limited | Administrative & support | 1992 |
| Poppin Commerce Ltd | Wholesale & retail | 2024 |
| Povey Developments Ltd | Real estate | 2020 |
| Precision Contract Flooring Limited | Construction | 2016 |
| Prestige Lemanski Tour Ltd | Administrative & support | 2014 |
| PRH Property Management Limited | Real estate | 2010 |
| Price Courier Ltd | Transport & logistics | 2025 |
| Primacare Holdings Limited | Professional & scientific | 2014 |
| Primacare Limited | Manufacturing | 2004 |
| Primacare Trustee Limited | Financial services | 2024 |
| Prize Play Competitions Ltd | Arts & recreation | 2025 |
| Prmc Property Management Company Ltd | Real estate | 2023 |
| Pro Athlete Supplementation Limited | Health & social care | 2006 |
| Pro Spark Electrical Services Limited | Construction | 2015 |
| PULSE101 Ltd | Arts & recreation | 2020 |
| Purflux Filtration Limited | Manufacturing | 1961 |
| Purpledogcompany.Com Ltd | Administrative & support | 2020 |
| Q Trauma Solutions Ltd | Administrative & support | 2025 |
| Quarrymens Arms Ltd | Hospitality | 2025 |
| Quartz Sinks Limited | Manufacturing | 2025 |
| R & M Properties (SW) Limited | Construction | 2025 |
| R & M Waste Removals Ltd | Water & waste | 2025 |