| Morgan Rendering and Plastering Ltd | Construction | 2023 |
| Morgan&Co Barbers Ltd | Other services | 2021 |
| Morris Property Developments Ltd | Construction | 2021 |
| Mosaic Business Consultants Limited | Professional & scientific | 2010 |
| Mota Limited | Real estate | 1960 |
| Motion Graphics Ltd | Information & communication | 2022 |
| Moto Developments Ltd | Real estate | 2025 |
| Moto Martyn Motorcycle Sales Ltd | Wholesale & retail | 2023 |
| Moto Martyn Motorcycles Ltd | Wholesale & retail | 2023 |
| Motofix Garage Limited | Wholesale & retail | 2018 |
| Motomec (Aberdare) Limited | Wholesale & retail | 2004 |
| Mount Pleasant Hotel Limited | Hospitality | 2015 |
| MP Jones Property Ltd | Construction | 2023 |
| Mpathy Solutions Limited | Information & communication | 2000 |
| MR MC Barbers Ltd | Other services | 2025 |
| MR Racing Limited | Arts & recreation | 2022 |
| MSN Property Group Ltd | Real estate | 2025 |
| Mullan Electrical Solutions Ltd | Construction | 2026 |
| Muzz Jointing Ltd | Construction | 2025 |
| MWW Property Developments Ltd | Real estate | 2026 |
| MWW Property Renovation Ltd | Construction | 2025 |
| MYA LEE Services Limited | Construction | 2018 |
| N & S Air Conditioning Ltd | Construction | 2017 |
| N-Deavor Ltd | Wholesale & retail | 2021 |
| N.Bsealant’S Ltd | Construction | 2026 |
| Nantmelyn Limited | Real estate | 2013 |
| Nationwide Claims Centre Limited | Financial services | 2005 |
| NCF Accountancy Limited | Professional & scientific | 2019 |
| Nextgen AI Careers Limited | Information & communication | 2025 |
| Nightfire Games Ltd | Wholesale & retail | 2026 |
| NK. Hughes. Construction Ltd | Construction | 2026 |
| Noah Properties Limited | Real estate | 2012 |
| NOD to the Dog Ltd | Wholesale & retail | 2026 |
| NT Catering Limited | Hospitality | 2013 |
| Nviro Group Limited | Construction | 2025 |
| Oaklands Properties (Aberdare) Limited | Households | 1992 |
| Oakwell Kitchens Ltd | Construction | 2024 |
| Oakwell Masonry Services Ltd | Construction | 2017 |
| Obsession Entertainment Limited | Arts & recreation | 2022 |
| Octane Plant Services Ltd | Construction | 2019 |
| Olympus Trade Limited | Wholesale & retail | 2018 |
| Olympus Travel Ltd | Administrative & support | 2022 |
| OMC Technologies (UK) Limited | Construction | 2011 |
| One Stop Coffee Shop Ltd | Wholesale & retail | 2023 |
| Oriental House Tasty Ltd | Hospitality | 2025 |
| Orthobrace Limited | Wholesale & retail | 2016 |
| Osmans Kitchen Ltd | Hospitality | 2020 |
| Otterllie & Co Limited | Professional & scientific | 2022 |
| OUR Aberdare Limited | Other services | 2020 |
| OUR Sacred Spirit Ltd | Wholesale & retail | 2024 |
| P Hawkes Construction Limited | Construction | 2015 |
| P N Wellness Limited | Other services | 2023 |
| P&H Landscaping Ltd | Administrative & support | 2022 |
| P&H Utilities Ltd | Construction | 2020 |
| P. Morgan Plant Hire & Civil Engineering Limited | Construction | 1997 |
| Pacific Fitness Limited | Arts & recreation | 2012 |
| Padsc Ltd | Information & communication | 2020 |
| PAN Media Group Ltd | Information & communication | 2020 |
| Parker & SON Construction Limited | Construction | 2004 |
| Parle Farms Limited | Agriculture & fishing | 2020 |
| Parle Services Limited | Real estate | 2004 |
| Pass With ME Ltd | Education | 2024 |
| Paul Jones Wealth Management Limited | Financial services | 2016 |
| Paws on the Moon Ltd | Manufacturing | 2019 |
| PCL UK Holdings Limited | Financial services | 2022 |
| Pcssa Property Ltd | Real estate | 2022 |
| Peak Landscaping & Construction Ltd | Administrative & support | 2022 |
| Peak Strength Gym Ltd | Arts & recreation | 2024 |
| Pearce Construction & Developments Ltd | Construction | 2023 |
| Pearson and Cable Properties Ltd | Real estate | 2019 |
| Pearson Investment Capital Ltd | Real estate | 2016 |
| Pearson Plumbing & Heating Ltd | Construction | 2023 |
| Pendragon Green Ltd | Information & communication | 1997 |
| Pengwin Care Limited | Education | 2019 |
| Pengwin Employee Ownership Trustee Limited | Professional & scientific | 2025 |
| Penhill Jones Property Ltd | Real estate | 2020 |
| Pennant Walters (Maesgwyn) Holdings Limited | Financial services | 2009 |
| Pennant Walters (Pant Y WAL) Holdings Limited | Financial services | 2011 |
| Pennant Walters (Pywx) Holdings Limited | Financial services | 2015 |
| Pennant Walters (Pywx) Limited | Energy | 2012 |
| Pennant Walters (SW) Limited | Energy | 2022 |
| Pennant Walters Hirwaun (Holdings) Limited | Financial services | 2013 |
| Pennant Walters Mcyc Limited | Energy | 2020 |
| Pennant Walters ML Limited | Energy | 2020 |
| Pennant Walters MM Limited | Energy | 2020 |
| Pennant Walters MYG Limited | Energy | 2021 |
| Peppino's Akar Ltd | Hospitality | 2026 |
| Philips Construction Ltd | Construction | 2024 |
| Philips Developments Ltd | Real estate | 2025 |
| Philtronics Limited | Manufacturing | 2003 |
| Philtronics Solutions Limited | Construction | 2018 |
| Phoenix Performance Ltd | Arts & recreation | 2025 |
| Pioneer Safety Rails Ltd | Construction | 2020 |
| Pipsie Ltd | Information & communication | 2022 |
| PJ Dare Limited | Hospitality | 2017 |
| PJB Mechanical Ltd | Professional & scientific | 2024 |
| PJI Works Ltd | Real estate | 2015 |
| PJM Pipelayers Contractors Limited | Construction | 2017 |
| Pmjb Limited | Real estate | 2014 |
| Pmsocials Ltd | Information & communication | 2025 |