| TS GAS Limited | Construction | 2013 |
| Tsgg License Ltd | Wholesale & retail | 2025 |
| Turner Resources L.P. | | 2018 |
| Turtle Purple Limited | Wholesale & retail | 2017 |
| TWENTY20 Scaffolding Services Ltd | Construction | 2019 |
| Tyre Busters Limited | Wholesale & retail | 2023 |
| Tywi AI Services Limited | Agriculture & fishing | 2025 |
| Tywi Eyecare Ltd | Wholesale & retail | 2024 |
| Tywi Health Ltd | Health & social care | 2025 |
| Tywi Planning Services Ltd | Professional & scientific | 2025 |
| Tywi Valley Foods Limited | Manufacturing | 2004 |
| TŶ Cwningen CYF | Hospitality | 2022 |
| Uberwagon Ltd | Wholesale & retail | 2021 |
| Ubuntu Consultancy Services Ltd | Professional & scientific | 2024 |
| UK Executive Consulting & Training Ltd | Information & communication | 2019 |
| UK Industrial Training Services Ltd | Transport & logistics | 2019 |
| Umfundi Ltd | Information & communication | 2024 |
| Unit 9 Community Leisure Ltd | Arts & recreation | 2022 |
| Upland Commodities PC | | 2018 |
| Upland Construction (Wales) Ltd | Construction | 2000 |
| Uplands Developments Wales Limited | Construction | 2017 |
| Upton Estates Limited | Real estate | 2020 |
| Urbanform Limited | Extraterritorial | 1989 |
| USA Chicken Kebab Fast Food Ltd | Wholesale & retail | 2025 |
| UTK Holdings Limited | Financial services | 2025 |
| UW Centre for Advanced Batch Manufacture Limited | Professional & scientific | 2014 |
| UW Pensions Scheme Ltd | Other services | 2020 |
| Uwchgwili Farm Limited | Agriculture & fishing | 2017 |
| Uwtsd Innovation Centres Ltd | Real estate | 2019 |
| Uwtsd Investments Limited | Financial services | 2015 |
| V15 Consulting Ltd | Professional & scientific | 2024 |
| VAL ZIE Consulting Limited | Professional & scientific | 2012 |
| Valepoint Property Ltd | Real estate | 2026 |
| Valibrah Limited | Other services | 2017 |
| Valley Cleaning Group Ltd | Households | 2023 |
| Valley Enterprises Ltd | Manufacturing | 2021 |
| Veeprotec Ltd | Wholesale & retail | 2021 |
| Vegan Plus Limited | Manufacturing | 2020 |
| Velocity Detection Ltd | Manufacturing | 2023 |
| Venture Capital Global Limited | Wholesale & retail | 2017 |
| Verlands Properties Limited | Wholesale & retail | 2010 |
| Veterans Village Ltd | Wholesale & retail | 2019 |
| VGR Windscreens Limited | Wholesale & retail | 2024 |
| Vicbake Limited | Real estate | 2013 |
| Village Green PUB Company Limited | Hospitality | 2016 |
| Vincent Jones & SON Ltd | Transport & logistics | 2013 |
| Violence Skateboards Ltd | Manufacturing | 2025 |
| Viridyn Care Ltd | Wholesale & retail | 2025 |
| Visionmark Ltd | Professional & scientific | 1999 |
| Visionplus (Carmarthen) Limited | Wholesale & retail | 1985 |
| Vizual Alchemy -UK Limited | Administrative & support | 2016 |
| Vowley Management Company Ltd | Arts & recreation | 2019 |
| W & F Hughes Properties Limited | Real estate | 2018 |
| W&E Developments Ltd | Construction | 2016 |
| W.G. Tyres Limited | Wholesale & retail | 2014 |
| W.Kingsbury Limited | Wholesale & retail | 1946 |
| W.M. & D.M. Morgan Limited | Agriculture & fishing | 1984 |
| Waldron Jones Property Ltd | Real estate | 2026 |
| Wales Pension Partnership Investment Management Company Limited | Financial services | 2025 |
| Wallets Capital Ltd | Information & communication | 2021 |
| Walter Raymond Holdco Ltd | Financial services | 2023 |
| Wand Inspection Services Ltd | Professional & scientific | 2025 |
| Wansford Holdings Limited | Extraterritorial | 1996 |
| Waste Trade Ltd | Water & waste | 2018 |
| Waterloo House Properties Ltd | Real estate | 2026 |
| Watling Automobiles Ltd | Wholesale & retail | 2023 |
| Wayne Smith Limited | Transport & logistics | 2024 |
| WDW Davies Ltd | Real estate | 2025 |
| WE ARE MAD Collective Limited | Arts & recreation | 2017 |
| Webb Gibb Co Limited | Wholesale & retail | 2011 |
| Wellbeing Skincare Limited | Wholesale & retail | 2009 |
| Welsh Baptist Union Corporation,Limited(The) | Other services | 1921 |
| Welsh Clay Target Shooting Association Limited | Arts & recreation | 2001 |
| Welsh Orthopaedic Society Limited | Health & social care | 2023 |
| Welsh Railway Trust Ltd | Other services | 1975 |
| Welsh Shield Limited | Administrative & support | 2026 |
| Wendy and Iwan Property Limited | Households | 2025 |
| Wern Properties Limited | Real estate | 2023 |
| West Health (Dyfed) Ltd | Health & social care | 2026 |
| West Wales Action for Mental Health | Health & social care | 1995 |
| West Wales Contracting Limited | Construction | 2006 |
| West Wales Dental Implant Clinic Limited | Health & social care | 2011 |
| West Wales First AID Ltd | Education | 2026 |
| West Wales Holiday Cottages Ltd | Other services | 2019 |
| West Wales Homes Limited | Construction | 2008 |
| West Wales Lubricants Limited | Wholesale & retail | 2014 |
| West Wales Motorsport Fabrication Limited | Manufacturing | 2003 |
| West Wales Rally Hire Ltd | Wholesale & retail | 2022 |
| Westcoast Doors Ltd | Construction | 2024 |
| Western Welsh Financial Services (Carmarthenshire) Limited | Financial services | 2011 |
| Westfield A'I FAB Limited | Agriculture & fishing | 2019 |
| Wexfield Limited | Hospitality | 2013 |
| White Direct Transport Ltd | Agriculture & fishing | 2017 |
| White Oak Property Investments Ltd | Real estate | 2020 |
| Whitland Green Park Limited | Construction | 2004 |
| WHO IAM Services Ltd | Information & communication | 2026 |
| Whodunit Ltd | Arts & recreation | 2023 |
| Wilca Holdings Ltd | Real estate | 2021 |
| Wild Horizons Ltd | Arts & recreation | 2020 |
| Wildcrest Project PC | | 2018 |