| MJ Living Space Ltd | Real estate | 2014 |
| MJS Consultancy Solutions Limited | Health & social care | 2024 |
| Monkstone Properties Limited | Real estate | 1956 |
| Monotech Ltd | Professional & scientific | 2018 |
| Movievents Limited | Information & communication | 2011 |
| MPK Consultants Ltd | Professional & scientific | 2024 |
| MSC Services Limited | Professional & scientific | 2016 |
| MSR Foods Limited | Hospitality | 2019 |
| Mygolf.Ai Ltd | Information & communication | 2024 |
| ND Construct Limited | Construction | 2006 |
| NE61 Developments Ltd | Real estate | 2022 |
| New Leaf Property Group Ltd | Real estate | 2018 |
| Newgale Consulting Limited | Information & communication | 2014 |
| Next Generation Mortgages Limited | Professional & scientific | 1998 |
| NFM Systems Limited | Information & communication | 2014 |
| Nodyn Glas Music Therapy Limited | Education | 2025 |
| Northbridge Payroll & Compliance Ltd | Professional & scientific | 2026 |
| O D Asset Management Ltd | Financial services | 2018 |
| O.F.I. Solutions Limited | Information & communication | 2013 |
| OB Plumbing & Heating Services Ltd | Construction | 2023 |
| Obrien Electrical Ltd | Construction | 2023 |
| Oluvium Limited | Professional & scientific | 2017 |
| Omara Ltd | Wholesale & retail | 2024 |
| One O'Clock Gate Limited | Wholesale & retail | 2021 |
| OPT2TRADES Limited | Financial services | 2025 |
| Oscha Holdings Ltd | Financial services | 2020 |
| Osiris Software Services Limited | Information & communication | 2025 |
| Overhill Ltd | Wholesale & retail | 2022 |
| P Wise Catering Ltd | Hospitality | 2018 |
| Paam Limited | Real estate | 2015 |
| Paul Davies Aviation Limited | Professional & scientific | 2014 |
| Penarth Brands Ltd | Wholesale & retail | 2021 |
| Phil Harries Developments Limited | Real estate | 2011 |
| Picardy Landscapes Limited | Administrative & support | 2025 |
| PJB Diagnostics Limited | Health & social care | 2023 |
| PJH Property Holdings Ltd | Construction | 2022 |
| Planit Design Solutions Limited | Construction | 2014 |
| PM Air Ltd | Construction | 2019 |
| Potter A'I Gwmni Cyfyngedig | Professional & scientific | 2026 |
| Powell Marine & Cargo Ltd. | Professional & scientific | 2007 |
| Primera Fila Ltd | Real estate | 2020 |
| Print Metal Fabrication Ltd | Manufacturing | 2024 |
| Privart Ltd | Wholesale & retail | 2022 |
| Procurement Wales Consultancy Ltd | Professional & scientific | 2021 |
| Puffin Services Limited | Information & communication | 2024 |
| R E Allsop Ltd | Administrative & support | 2017 |
| R S (Dinas) Ltd | Hospitality | 2017 |
| Rafa JSY Ltd | Professional & scientific | 2025 |
| RAY John (Vehicle Management) Limited | Other services | 2019 |
| Record One Ltd | Construction | 2021 |
| Recordiau Tant Cyfyngedig | Information & communication | 2003 |
| Redcliffe Import & Export Limited | Wholesale & retail | 2010 |
| Redpoint Holdings Limited | Real estate | 2025 |
| Rees Family Ltd | Administrative & support | 2026 |
| Reeves Retail Planning Consultancy Ltd | Professional & scientific | 2013 |
| Restorative Approaches Limited | Public administration | 2013 |
| Ribbons Preschool Limited | Education | 2019 |
| Riblex Limited | Information & communication | 2017 |
| Ring-A-Roast Limited | Hospitality | 2004 |
| Rj&Jb Services Ltd | Administrative & support | 2026 |
| RMR Fabrications Ltd | Other services | 2025 |
| RMS Digital Ltd | Information & communication | 2024 |
| Robin Ellis Ltd | Arts & recreation | 2024 |
| Roll Blue Limited | Information & communication | 2012 |
| Roofcleanwales Ltd | Construction | 2022 |
| Roote Limited | Real estate | 2025 |
| Route Fitness Ltd | Wholesale & retail | 2026 |
| Rowan House Penarth Freehold Ltd | Households | 2016 |
| RS Compressors Ltd | Professional & scientific | 2022 |
| S P D Lofts Limited | Construction | 2025 |
| S-Cubed Consultants Limited | Professional & scientific | 2002 |
| SAP Food Consultants Ltd | Hospitality | 2018 |
| Screen Magic Limited | Professional & scientific | 1995 |
| Shore Rowing Ltd | Manufacturing | 2026 |
| Shutter Hire Ltd | Professional & scientific | 2021 |
| Slgm Consultancy Limited | Professional & scientific | 2021 |
| Smartstats Limited | Construction | 2014 |
| Southall Consultants Ltd | Professional & scientific | 2026 |
| Southra Estates Ltd | Real estate | 2020 |
| Spectrum Arddangosfeydd Cymru Limited | Construction | 2015 |
| SPH Construction Ltd. | Construction | 2015 |
| Spike Golf Ltd | Manufacturing | 2022 |
| Spirit Anchor Limited | Professional & scientific | 2023 |
| SPP Dental Limited | Health & social care | 2006 |
| SSD Limited | Other services | 1993 |
| Stamry Limited | Construction | 2022 |
| Starlings Electrical Ltd | Construction | 2022 |
| Story Mode Ltd | Information & communication | 2024 |
| Sttc Limited | Health & social care | 2019 |
| Stumpbusters (South Wales) Ltd | Agriculture & fishing | 2002 |
| Sunset Group (Cardiff) Ltd | Real estate | 2020 |
| Susannah's Homes Ltd | Real estate | 2026 |
| T.J.Bird & Sons Limited | Agriculture & fishing | 1948 |
| Tawc Ltd | Real estate | 2023 |
| TH Golf Ltd | Wholesale & retail | 2021 |
| That Works Limited | Information & communication | 2023 |
| THE Bike Buyer Ltd | Wholesale & retail | 2017 |
| THE Fiit Group Limited | Arts & recreation | 2021 |
| THE Lloyd Thomas Partnership Ltd | Hospitality | 2008 |
| THE Pont Collective Limited | Professional & scientific | 2025 |