| MR Fridge Ltd | Wholesale & retail | 2023 |
| MR Property Development Merthyr Ltd | Real estate | 2024 |
| MSC Rental Properties Ltd | Real estate | 2021 |
| Mscl Rental Properties Ltd | Real estate | 2024 |
| MSW Business Solutions Limited | Administrative & support | 2014 |
| Muntarbhorn Ltd | Other services | 2015 |
| Murphy and Murphy (South Wales) Limited | Construction | 2019 |
| Murphy and Sons Roofing Limited | Construction | 2011 |
| Murphy Corke Developments Limited | Construction | 2014 |
| Murray’S Property Investments Ltd | Real estate | 2025 |
| Muso App Limited | Other services | 2021 |
| MV Logistics & Storage Limited | Transport & logistics | 2023 |
| MWB 141 Services Limited | Construction | 2020 |
| N Dudley Services Limited | Construction | 2019 |
| N J Samuel Services Limited | Construction | 2019 |
| Nartas Bar Limited | Hospitality | 2009 |
| Nathan Morgan Limited | Information & communication | 2016 |
| Nathella Painting and Decorating Limited | Construction | 2024 |
| National Training Federation for Wales Ltd | Other services | 2002 |
| Nationwide Van Driver Limited | Transport & logistics | 2020 |
| Natural Affinity Therapy Ltd | Other services | 2024 |
| Neath Valeting Auto-Repair & Tires Ltd | Manufacturing | 2019 |
| Neighbourhood Property Management Limited | Other services | 2006 |
| Neil Merry Rail Services Limited | Construction | 2016 |
| New JEN Chang Ltd. | Hospitality | 2017 |
| New PAK HO Take-Away Ltd | Hospitality | 2026 |
| New Pathways Family Friendly Therapeutic Centre of Excellence | Health & social care | 2008 |
| New Trefechan Fish Bar Limited | Hospitality | 2019 |
| New Whitehorse Twyn Ltd | Hospitality | 2025 |
| NG33 Ltd | Hospitality | 2025 |
| Ngage Holdings Limited | Financial services | 2020 |
| Ngage Resourcing Ltd | Administrative & support | 2020 |
| Nigel Hodge Forensic Science Limited | Professional & scientific | 2011 |
| Night X Limited | Hospitality | 2023 |
| NJS Installation Services Ltd | Financial services | 2024 |
| NM Property Limited | Real estate | 2025 |
| NMA NWA Ltd | Real estate | 2022 |
| NMC Maintenance Services Limited | Construction | 2023 |
| Noble Futures Childcare Ltd | Health & social care | 2021 |
| Novochem Limited | Wholesale & retail | 2003 |
| Novus DST Limited | Professional & scientific | 2026 |
| NSK Elite Services Limited | Wholesale & retail | 2024 |
| O Gymru I'R BYD Ltd | Professional & scientific | 2004 |
| O Publishing & Media Limited | Information & communication | 2017 |
| O.P. Chocolate Limited | Manufacturing | 1990 |
| Oakdale House Limited | Hospitality | 2022 |
| One Stop Business Support Group Limited | Construction | 2025 |
| Onwards Rail Ltd | Transport & logistics | 2019 |
| Opus 03 Ltd | Administrative & support | 2008 |
| Orbitgeo Ltd | Professional & scientific | 2026 |
| Oriel Blinds & SON Limited | Administrative & support | 2006 |
| Orion Clinical Services (Australia) PTY Limited | Professional & scientific | 2001 |
| Orion Clinical Services Limited | Professional & scientific | 1997 |
| Orion LR Limited | Professional & scientific | 2011 |
| OSG Security Limited | Administrative & support | 2025 |
| Oshie's Kitchen Ltd | Hospitality | 2017 |
| OUT of the Box Flower Preservation Limited | Manufacturing | 2024 |
| OUT of the Box Memorial Limited | Manufacturing | 2024 |
| Overland Educational Travel Limited | Administrative & support | 2021 |
| OZ Tech Services Limited | Construction | 2018 |
| P & C Building & Management Solutions Limited | Construction | 2016 |
| P Brogden Properties Limited | Real estate | 2009 |
| P&T Prop Renovations Limited | Construction | 2025 |
| Padds Vets Limited | Professional & scientific | 2026 |
| Page Rail Ltd | Construction | 2019 |
| Paimee Ltd | Hospitality | 2024 |
| Palace Homes (Wales) Limited | Construction | 2007 |
| Palo Property Ltd | Real estate | 2026 |
| Pant Properties Limited | Real estate | 2016 |
| Pantyscallog Steakhouse Ltd | Hospitality | 2020 |
| Park Heating & GAS Services Limited | Construction | 2018 |
| Parkload Limited | Transport & logistics | 1997 |
| Parkside Properties SW Ltd | Construction | 2024 |
| Pasta Bella Ltd | Manufacturing | 2024 |
| Patagonia MT Ltd | Hospitality | 2024 |
| Paula Davies Catering Limited | Hospitality | 2005 |
| Pbsplus Ltd | Education | 2019 |
| Pearce Creative Services Ltd | Professional & scientific | 2015 |
| Pencerrig Properties Limited | Real estate | 2023 |
| Pennar Holdings Limited | Extraterritorial | 2013 |
| Pennar Properties Limited | Real estate | 2015 |
| Pensord Digital Limited | Manufacturing | 2014 |
| Pensord Holdings Limited | Manufacturing | 2003 |
| Pensord Press Limited | Manufacturing | 1968 |
| Pensord TWENTY10 Limited | Manufacturing | 2010 |
| Penydarren Boys and Girls Club | Arts & recreation | 2011 |
| Penydarren Motors Ltd | Wholesale & retail | 2026 |
| Peregrim Limited | Construction | 2008 |
| Perfect Event Group Limited | Professional & scientific | 2019 |
| PFL Painting and Decorating Limited | Construction | 2018 |
| Phasebox Solutions Limited | Other services | 2020 |
| Phasor Electrical Services Limited | Construction | 2025 |
| Phasor Holdings Limited | Financial services | 2019 |
| PHD Lettings and Investments Limited | Real estate | 2019 |
| Phil Newman Cars Limited | Wholesale & retail | 2024 |
| Philip Price Commercial Vehicle Services Limited | Wholesale & retail | 2015 |
| Phillip Cope Financial Services Limited | Financial services | 2007 |
| Phoenix Custom Creations Ltd | Wholesale & retail | 2025 |
| Phoenix Fashion & Footwear Limited | Wholesale & retail | 2012 |
| Phoenix Fencing & Construction Ltd | Construction | 2021 |