| Remy and Matt Ltd | Manufacturing | 2017 |
| Reset Wellness Studio Ltd | Other services | 2025 |
| Resolute Financial Planning Ltd | Financial services | 2012 |
| Restan Associates Limited | Professional & scientific | 2013 |
| Result Logistics and Cleaning Limited | Transport & logistics | 2024 |
| Revive Wellness Club Ltd | Health & social care | 2025 |
| RGJ Building Services Ltd | Construction | 2015 |
| Rhondda-Cynon-Taf & Merthyr Tydfil Business Crime Reduction Partnership Ltd | Other services | 2008 |
| Rhoscolyn Consulting Ltd | Professional & scientific | 2026 |
| Rhosyn Property Management Ltd | Real estate | 2023 |
| Richard S Lobb Technical Services Limited | Manufacturing | 2015 |
| Rici Ltd | Construction | 2019 |
| Ridgestone Construction Ltd. | Construction | 2012 |
| Riff Wolf Beerworks Ltd | Manufacturing | 2025 |
| Riform Limited | Construction | 2017 |
| Right 1ST Time Recruitment Limited | Administrative & support | 2024 |
| Right Track Guitar Limited | Education | 2004 |
| RIH Rail Limited | Construction | 2019 |
| Risk Consultancy & Training Ltd | Professional & scientific | 2024 |
| RJM Solicitors Limited | Professional & scientific | 2008 |
| Rjmarshall Construction Ltd | Construction | 2025 |
| RJT Morgan Limited | Financial services | 2024 |
| RL Real Estate (Wales) Limited | Real estate | 2025 |
| RLB Rail Services Ltd | Construction | 2014 |
| RM Alliance Ltd | Health & social care | 2023 |
| RMC Engineering & Automation Ltd | Professional & scientific | 2024 |
| Roblyn Properties Ltd | Real estate | 2003 |
| Roma Decoration Limited | Construction | 2022 |
| Romlay-Frey Commercial Properties Ltd | Other services | 2020 |
| Roof DR Ltd | Construction | 2025 |
| Root News Ltd | Information & communication | 2014 |
| Rose & Crown Limited | Hospitality | 2016 |
| Rosper Engineering Services Ltd | Construction | 2013 |
| RP Hydro Survey Consultants Ltd | Mining & quarrying | 2020 |
| RR Grocery Ltd | Wholesale & retail | 2022 |
| RR QA Consultancy Services Ltd | Administrative & support | 2020 |
| RS United Groups Ltd | Wholesale & retail | 2023 |
| RSE Property Development Ltd | Real estate | 2024 |
| RT Manning & SON Brickwork & Groundwork Ltd | Construction | 2024 |
| RT Williams Vehicle Repair & Recovery Limited | Wholesale & retail | 2019 |
| Ruby Property Holdings Ltd | Real estate | 2025 |
| Rudi & Julie Property Limited | Households | 2024 |
| Rule Developments Ltd | Real estate | 2026 |
| Rumble Properties Ltd | Real estate | 2018 |
| RVE Properties Ltd | Real estate | 2025 |
| Rwjtransport Ltd | Transport & logistics | 2024 |
| Rynik Carpentry and Building Services Limited | Construction | 2011 |
| S & J Products Limited | Real estate | 1990 |
| S & R Carpentry & Building Limited | Construction | 2008 |
| S & R Property Lettings Limited | Real estate | 2024 |
| S R Building Solutions Limited | Construction | 2007 |
| S Williams Electrical Services Ltd | Construction | 2026 |
| S&D Fade Barber Ltd | Other services | 2025 |
| S&D Top Barber Ltd | Other services | 2026 |
| S&G Properties South Wales Limited | Real estate | 2025 |
| S&S 1ST Class Rentals Limited | Real estate | 2025 |
| S&S Logistical Services Ltd | Administrative & support | 2017 |
| S&S Sparkle & Shine Cleaning Services Ltd | Administrative & support | 2023 |
| S&S Williams Properties Ltd | Households | 2019 |
| S-O Acquisition Corp Limited | Financial services | 2018 |
| S-O MID Corp Limited | Financial services | 2018 |
| S-O SUB Corp Limited | Financial services | 2018 |
| S.Burris Engineering Limited | Professional & scientific | 2016 |
| Safehaven Ventures Ltd | Wholesale & retail | 2025 |
| Safer Merthyr Tydfil Limited | Public administration | 1997 |
| Salon L Limited | Other services | 2013 |
| Salon Q Beauty Ltd | Other services | 2025 |
| Salubrious Developments Ltd | Real estate | 2002 |
| Samis Kebab Ltd | Hospitality | 2024 |
| Sammy D Mulan Limited | Hospitality | 2015 |
| SAN Fernando Healthcare Ltd | Health & social care | 2022 |
| SAN Retailers Ltd | Wholesale & retail | 2024 |
| Sandbrook Residents Management Company Ltd | Households | 2022 |
| SAR Trade Aero Ltd | Wholesale & retail | 2024 |
| Sashjarr Rail Ltd | Other services | 2019 |
| Satori Flowers and Design Limited | Wholesale & retail | 2013 |
| Save Dosh Ltd | Wholesale & retail | 2013 |
| SBW Survey Ltd | Construction | 2024 |
| SCOFF-22 Ltd | Hospitality | 2022 |
| Scott MAC Ltd | Wholesale & retail | 2025 |
| Screen Genie Windscreens Ltd | Wholesale & retail | 2016 |
| SD Automation Limited | Professional & scientific | 2024 |
| Sean Craze Rail Ltd | Construction | 2019 |
| Security (Cymru) Limited | Administrative & support | 2013 |
| Senatus Business Solutions Ltd | Professional & scientific | 2020 |
| Serenity Tanning Limited | Other services | 2024 |
| Seven Seas Tours and Travels Ltd | Administrative & support | 2025 |
| Sevenem Services Limited | Hospitality | 2008 |
| SG Autoglass Wales Limited | Wholesale & retail | 2025 |
| Sgscreensuk Ltd | Wholesale & retail | 2025 |
| Shadow Plant Hire Ltd | Administrative & support | 2016 |
| Shadow Surfacing Ltd | Construction | 2020 |
| Shannons Healthcare Limited | Health & social care | 2023 |
| SHE Thrives Wellness CIC | Education | 2024 |
| Side Studio Props CYF | Manufacturing | 2025 |
| Sight Care Optical Ltd | Wholesale & retail | 2010 |
| Silverline Estates Ltd | Households | 2019 |
| Silveroak Building Solutions Ltd | Construction | 2024 |
| Simbec Research Limited | Professional & scientific | 1974 |
| Simbec-Orion Group Limited | Health & social care | 2013 |