| Total Home Improvements (South Wales) Limited | | 1983 |
| Total Service Solutions SW Limited | Administrative & support | 2018 |
| Total Vent Systems Limited | Construction | 2026 |
| TPH Chiropractic Clinic Limited | Health & social care | 2010 |
| Tptf Ltd | Water & waste | 2025 |
| Track and Train Services Limited | Professional & scientific | 2020 |
| Tradie Media Ltd | Professional & scientific | 2026 |
| Training in Motion Limited | Extraterritorial | 2013 |
| Trans Track UK Ltd | Transport & logistics | 2018 |
| Transit Engineering Limited | Manufacturing | 2007 |
| Treasure Accounting Limited | Extraterritorial | 2014 |
| Treasure Quarters Ltd | Wholesale & retail | 2024 |
| Trem-Y-Mynydd Court Management Company Limited | Households | 2005 |
| Tripple T Limited | Hospitality | 2019 |
| Troubleshooters (Services for Business) Limited | Professional & scientific | 1999 |
| True Flight Golf Balls Limited | Wholesale & retail | 2025 |
| Trusthobbs Limited | Construction | 2013 |
| Trysull Gold Ltd | Wholesale & retail | 2025 |
| TSH Group of Companies Ltd | Manufacturing | 2023 |
| TSM Construction Contractors Ltd | Manufacturing | 2022 |
| TSM Logistics & Removals Ltd | Transport & logistics | 2019 |
| Tweenie Tots Playschool Ltd | Education | 2013 |
| Twyn-Y-Ffrwd Inn Limited | Hospitality | 2017 |
| TY Gwyn GAS Services Ltd | Construction | 2019 |
| TY Gwyrdd Limited | Construction | 2022 |
| U4 Consultancy Ltd | Professional & scientific | 2025 |
| Ubrella Ltd | Hospitality | 2024 |
| UK Aire Ltd | Hospitality | 2021 |
| UK Standard Electrics Ltd | Construction | 2016 |
| Ultra Coat Ltd | Manufacturing | 2017 |
| Unit 10 Distribution Limited | Wholesale & retail | 2008 |
| Unit One Barbering Ltd | Other services | 2021 |
| Unity Technology Services Limited | Information & communication | 2024 |
| Urbanism Limited | Professional & scientific | 2018 |
| Urbanism Property Limited | Households | 2023 |
| USK Stoves Installations Ltd | Construction | 2019 |
| USK Stoves Limited | Wholesale & retail | 2015 |
| USK Stoves Trading Company Limited | Wholesale & retail | 2018 |
| USK Top Soil Ltd | Agriculture & fishing | 2026 |
| USK Vale Auto Services Limited | Wholesale & retail | 2022 |
| USK Vale Holdings Limited | Financial services | 2020 |
| USK Vale Poultry Limited | Agriculture & fishing | 2003 |
| USK Valley Spring Limited | Extraterritorial | 2000 |
| Utopia Beauty and Nails Limited | Other services | 2025 |
| Valentine's Tyres Ltd | Wholesale & retail | 2016 |
| Valley Carpets & Flooring Limited | Wholesale & retail | 2004 |
| Valley Residential Developments Ltd | Construction | 2026 |
| Valley Windscreens Limited | Wholesale & retail | 2022 |
| Valorise Energy Ltd | Professional & scientific | 2025 |
| Valtora Limited | Wholesale & retail | 2025 |
| Vaughan Training & Consultancy Ltd | Education | 2012 |
| Vedgrill Limited | Hospitality | 2023 |
| Velocity Automations Ltd | Information & communication | 2026 |
| Veltahunter Limited | Real estate | 2000 |
| Vera's Vessels Ltd | Wholesale & retail | 2021 |
| Vesta Estate Agents Limited | Real estate | 2026 |
| VG Engineering Consultants Limited | Professional & scientific | 2013 |
| VI Developments Ltd | Construction | 2022 |
| Vic-Ty-Rhy Homes Ltd | Real estate | 2022 |
| Victoria Fisher Ltd | Professional & scientific | 2021 |
| Vision West & Wales Limited | Administrative & support | 2016 |
| Voltsmart Holdings Ltd | Professional & scientific | 2026 |
| Voltsmart Operations Ltd | Professional & scientific | 2026 |
| W & B Properties (Holdings) Limited | Financial services | 2024 |
| W & B Properties Limited | Real estate | 2019 |
| W P Transport and Recovery Ltd | Transport & logistics | 2022 |
| W&B Estates Limited | Construction | 2011 |
| W&K Harris Properties Limited | Real estate | 2024 |
| WAE Power Ltd | Construction | 2026 |
| Waite and Co T/A Angelwoods Limited | Real estate | 2018 |
| Wake Enterprises Limited | Wholesale & retail | 2023 |
| Warren Angles Ltd | Wholesale & retail | 2025 |
| Waterloo Varna Ltd | Wholesale & retail | 2025 |
| Watkins & Gunn Limited | Professional & scientific | 2021 |
| Watkins and Walker Limited | Construction | 2009 |
| Watkins Property Services Limited | Construction | 2013 |
| Wavell Wright Ltd | Wholesale & retail | 2025 |
| Waypoint Aerospace Limited | Professional & scientific | 2012 |
| WB Landscaping & Building Limited | Administrative & support | 2025 |
| WE Adore Chores CYF | Administrative & support | 2025 |
| Weagan Building Contractors Limited | Construction | 2021 |
| Weagan Ltd | Construction | 2015 |
| Wearestrata Limited | Information & communication | 2026 |
| Weather Guard Flat Roofing Specialists Ltd | Construction | 2019 |
| Weather Guard Services Ltd | Construction | 2025 |
| Weatherhard Ltd | Construction | 2023 |
| Wedgwood Park Residents Management Company Limited | Households | 2017 |
| Weird Gloop Limited | Information & communication | 2017 |
| Weld Ltd | Real estate | 2023 |
| Welshbridge Estates Ltd | Hospitality | 2025 |
| Wessex Reynold Ltd | Wholesale & retail | 2025 |
| West MON RFC Limited | Arts & recreation | 2022 |
| WET Wednesdays Limited | Wholesale & retail | 2018 |
| WGG Glass Units Direct Limited | Construction | 2021 |
| Wheelhouse Parts Ltd | Wholesale & retail | 2025 |
| White Feather Inns Ltd | Hospitality | 2024 |
| Whitecroft Sales Ltd | Wholesale & retail | 2025 |
| Whitehall Doris Ltd | Wholesale & retail | 2025 |
| Whites Goods Ltd | Wholesale & retail | 2025 |
| Whittle Bates Ltd | Wholesale & retail | 2025 |