| MC Hand Carwash Ltd | Administrative & support | 2026 |
| Menter Iaith SIR Caerffili | Education | 2004 |
| Metters Utilities Limited | Construction | 2018 |
| Millennium House (Newport) Limited | Real estate | 2016 |
| Mini Miners Group Ltd | Health & social care | 2016 |
| Mixit Concrete Services Limited | Manufacturing | 2005 |
| ML Evans Construction Ltd | Construction | 2017 |
| Mlacroix Healthcare Limited | Health & social care | 2024 |
| Morgan Bertram Bespoke Builds Ltd | Construction | 2025 |
| Morgan Morris Scaffolding Limited | Construction | 2022 |
| Morgan Thomas Bryncoed Ltd | Agriculture & fishing | 2023 |
| Morton & Wheeler Holdings Limited | Financial services | 2018 |
| Morton-Roberts Consulting Engineers Limited | Professional & scientific | 2010 |
| MR Barbers Ystrad Limited | Other services | 2019 |
| MT Nails Spa Ltd | Other services | 2026 |
| Mummytar Limited | Financial services | 2020 |
| MVM Clothing Ltd | Wholesale & retail | 2019 |
| MVM Property Developers Ltd | Real estate | 2020 |
| Mynach GAP Limited | Households | 2023 |
| N.L.S Care and Support Ltd | Health & social care | 2025 |
| Nalc Limited | Real estate | 2015 |
| Natalie's Homes Ltd | Real estate | 2023 |
| Nathan Harrington Interiors Limited | Professional & scientific | 2018 |
| Nathan Speller the Bodyshop Co Ltd | Wholesale & retail | 2019 |
| Nathan Staples Plastering Ltd | Construction | 2025 |
| Nautilus Management Solutions Ltd | Professional & scientific | 2016 |
| Ndareda Data Services Ltd | Information & communication | 2024 |
| Network Training Services Ltd. | Education | 1991 |
| Norgine Limited | Manufacturing | 1926 |
| Nova Door Systems Ltd | Construction | 2021 |
| NSQ Tuition Limited | Education | 2026 |
| NXN Real Estate Limited | Real estate | 2024 |
| Oakmain Limited | Manufacturing | 1993 |
| Oakmain Properties Holdings Limited | Other services | 2003 |
| Ocean Software Limited | Information & communication | 2013 |
| OLC Electrical & Fire Ltd | Construction | 2025 |
| Ontrack With MGD Limited | Administrative & support | 2010 |
| Oowa Ltd | Construction | 2024 |
| Orange Grove Construction Limited | Construction | 2017 |
| Orion Photography Ltd | Professional & scientific | 2025 |
| P & a Transport (Sweepers) Limited | Administrative & support | 2003 |
| P&A Sweepers Holdings Limited | Financial services | 2021 |
| PACKHC2023 Ltd | Financial services | 2023 |
| PAK Sing 36 Limited | Hospitality | 2025 |
| Palladium Training & Consultancy Limited | Professional & scientific | 2004 |
| Paperclip Public & Media Relations Ltd | Professional & scientific | 2021 |
| Partmart Automotive Recycling Ltd | Water & waste | 2018 |
| Partnership of Care Limited | Hospitality | 2003 |
| Pccs Properties UK Limited | Real estate | 2024 |
| Pearl Aqua Gardens Ltd | Construction | 2024 |
| Penallta RFC Limited | Arts & recreation | 2015 |
| Pengam Partmart LLP | | 2007 |
| Pinebark (Properties) Limited | Real estate | 2019 |
| Pink Ladies Domestic Services Ltd | Administrative & support | 2025 |
| Pipe & Plate Services Ltd | Professional & scientific | 2022 |
| Pizzaland 1 Ltd | Hospitality | 2023 |
| PJ Infra Services Limited | Administrative & support | 2012 |
| PJC Investments Limited | Real estate | 2004 |
| Platinum Property Restorations Limited | Real estate | 2024 |
| Plumbing Hot Ltd | Construction | 2024 |
| POC Homecare Ltd | Health & social care | 2009 |
| POC Investments Ltd | Hospitality | 2007 |
| POC TDC Ltd | Hospitality | 2018 |
| Poletti Living Ltd | Real estate | 2025 |
| Pontllanfraith Car Company Limited(The) | Real estate | 1979 |
| Portofinoystrad Ltd | Hospitality | 2022 |
| Positive Signs (SW) Limited | Manufacturing | 2020 |
| Price & Co Farming Limited | Agriculture & fishing | 2002 |
| Price Holdings Limited | Financial services | 2002 |
| Pride of Place (Embroidery) Limited | Manufacturing | 1987 |
| Prime Property and Lettings Ltd | Real estate | 2020 |
| Proactive Maintenance Services Ltd | Other services | 2019 |
| Profess LPG Ltd | Wholesale & retail | 2011 |
| Promotos Limited | Arts & recreation | 2009 |
| Proper Waste Ltd | Water & waste | 2025 |
| PRW Construction Ltd | Construction | 2025 |
| Purple Fenix Ltd | Wholesale & retail | 2025 |
| R.D. Lewis & Sons Limited | Real estate | 1987 |
| Rachel's Cafe Limited | Hospitality | 2023 |
| Rapid Recovery & Delivery Ltd | Transport & logistics | 2025 |
| Rapport Financial Planning Ltd | Financial services | 2010 |
| RAT and Drain Solutions Limited | Water & waste | 2025 |
| RAW Bear Bodybuilding Limited | Professional & scientific | 2025 |
| Real Refurbishment Ltd | Construction | 2025 |
| REB Civils Group Limited | Construction | 2026 |
| REB Civils Ltd | Construction | 2024 |
| Revue Menswear Limited | Wholesale & retail | 2018 |
| Rhian Price CYF | Real estate | 2023 |
| Richards Foundations Ltd | Real estate | 2026 |
| RJ Rigging Ltd | Construction | 2021 |
| RMA Enclosures Limited | Manufacturing | 2003 |
| Roads + Rails Ltd | Construction | 2015 |
| Roxanne Green Management & Consultancy Ltd | Professional & scientific | 2024 |
| Ruck and Coal Collective CIC | Hospitality | 2026 |
| Ruck and Coal Kitchen Ltd | Hospitality | 2025 |
| Ryan Cochlin Building Services Ltd | Construction | 2021 |
| Ryan Landscaping Limited | Construction | 2014 |
| Ryan Walters Limited | Wholesale & retail | 2016 |
| S & L Wakefield Properties Limited | Real estate | 2021 |
| S M Accountancy (UK) Ltd | Professional & scientific | 2015 |