| State 1 Training and Response Limited | Education | 2025 |
| Stella Marris Ltd | Administrative & support | 2020 |
| Sterlini Residential Services Ltd | Real estate | 2019 |
| Strongwilled Ltd | Wholesale & retail | 2024 |
| Studio Sixteen Limited | Other services | 2024 |
| SUB Zero Ice Cream Limited | Manufacturing | 2003 |
| Subzero Ice Cream Retail Limited | Hospitality | 2025 |
| Sun on the Run (Williamstown) Ltd | Other services | 2018 |
| Sunbeam Tanning Ltd | Other services | 2025 |
| Survpro Limited | Professional & scientific | 2006 |
| Suthar Services Limited | Hospitality | 2025 |
| Swansea Render Systems Limited | Other services | 2021 |
| Synchronised Technology Limited | Professional & scientific | 2017 |
| T & J Livery Limited | Agriculture & fishing | 2025 |
| T.R.S. Engineering Limited | Wholesale & retail | 1986 |
| Taliesin Residential Home (Holdings) Limited | Financial services | 2025 |
| Taliesin Residential Home Limited | Health & social care | 2011 |
| Tarian Timepiece Co. Ltd | Manufacturing | 2025 |
| Taurgo Limited | Information & communication | 2024 |
| Taurgo Property Ltd | Real estate | 2025 |
| Taylors Fish and Chips Ltd | Hospitality | 2011 |
| Technicon Furnishers Ltd | Wholesale & retail | 2018 |
| Teds Construction Ltd | Professional & scientific | 2017 |
| Teds Development Ltd | Administrative & support | 2014 |
| Teds One Developments Ltd | Construction | 2018 |
| Teulu Property Ltd | Hospitality | 2026 |
| Teulu Travel Limited | Transport & logistics | 2018 |
| THE Christmas Shop Limited | Wholesale & retail | 2025 |
| THE Flower Room Florist Ltd | Wholesale & retail | 2018 |
| THE Health HUT RCT Limited | Health & social care | 2021 |
| THE Ivory Thread by EA Ltd | Wholesale & retail | 2026 |
| THE JSP Haven CIC | Education | 2025 |
| THE Salad Box Tonypandy Ltd | Hospitality | 2022 |
| THE Sofa Queen Ltd Ltd | Wholesale & retail | 2025 |
| THE Timekeepers Attic Ltd | Wholesale & retail | 2025 |
| THE Wishing Well RCT Ltd | Wholesale & retail | 2024 |
| The-Lost-Bricks Ltd | Wholesale & retail | 2024 |
| Thomas & Sons GBM Ltd | Construction | 2021 |
| Thomas Chapman Developments Ltd | Construction | 2024 |
| Thomas Jones and SON Limited | Wholesale & retail | 2004 |
| Thomas Lettings Limited | Real estate | 2013 |
| Three Pillars Financial Limited | Financial services | 2026 |
| Tillobie Plastics Limited | Manufacturing | 2017 |
| TJS Aerovision Ltd | Information & communication | 2025 |
| TL Nails&Spa 109 Ltd | Other services | 2026 |
| TL Survey Limited | Administrative & support | 2018 |
| TLA3 Limited | Arts & recreation | 2024 |
| TMJ Service Limited | Construction | 2023 |
| Tommorg Limited | Transport & logistics | 2025 |
| TON Taxis Ltd | Transport & logistics | 2020 |
| Tonypandy BID Ltd | Administrative & support | 2025 |
| Tracknash Limited | Construction | 2024 |
| Trade Tyres Tonypandy Limited | Wholesale & retail | 2016 |
| Trealaw Village Trust Ltd | Arts & recreation | 2009 |
| Treharne Travel Limited | Transport & logistics | 2010 |
| TRI W Limited | Construction | 2022 |
| Trott CP Limited | Other services | 2007 |
| Tubology Ltd | Wholesale & retail | 2026 |
| Tyrone Griffiths Funeral Services Ltd | Other services | 2018 |
| UK Salvage Car Parts Ltd | Wholesale & retail | 2017 |
| Unique Country Retreats Limited | Real estate | 2021 |
| United Retrofit UK Limited | Construction | 2026 |
| Valley Ceilings and Partitions Ltd | Construction | 2019 |
| Valley Media Ltd | Wholesale & retail | 2023 |
| Valued Pets Veterinary Practice Ltd | Professional & scientific | 2022 |
| Vicerail Ltd | Construction | 2017 |
| Vintilly Properties Ltd | Real estate | 2026 |
| VIP Fish Ltd | Wholesale & retail | 2025 |
| Vision Sportswear Ltd | Manufacturing | 2023 |
| Visual Media Limited | Professional & scientific | 2022 |
| W B Travel Ltd | Administrative & support | 2024 |
| Wall Armour, Advanced Render Systems Ltd | Construction | 2023 |
| Walters Builders Ltd | Construction | 2014 |
| Waltersparks Ltd | Construction | 2019 |
| Wellnesshealth Ltd | Health & social care | 2024 |
| Weston-Digital Limited | Information & communication | 2023 |
| Windyboots Ltd | Transport & logistics | 2020 |
| Wobble&Whisk Limited | Hospitality | 2025 |
| Woodward Taxation Services LLP | | 2025 |
| World Foods Camborne Ltd | Wholesale & retail | 2026 |
| XL Storage Limited | Administrative & support | 2024 |
| Ynyscynon Car Wash Express Ltd | Other services | 2022 |
| Ynyscynon MOT Centre Limited | Wholesale & retail | 2025 |
| Ziaum Ltd | Wholesale & retail | 2021 |
| ZR Building Ltd | Construction | 2025 |