| Tydfil Training Consortium Limited | Education | 1990 |
| Type Group Ltd | Financial services | 2025 |
| Tyreman Merthyr Ltd | Wholesale & retail | 2011 |
| Ukcesrpfpa CIC | Education | 2026 |
| Unique Little Gift Shop Limited | Wholesale & retail | 2014 |
| United Travel Merthyr Ltd | Administrative & support | 2024 |
| Unitus Golf Ltd | Manufacturing | 2025 |
| Unleash Your Potential Ltd | Professional & scientific | 2014 |
| Unspoken Clothing Limited | Wholesale & retail | 2025 |
| USK Valley Services Ltd | Transport & logistics | 2019 |
| V&P Mini Market Ltd | Wholesale & retail | 2025 |
| Vale CRW Ltd | Construction | 2019 |
| Valley Recruitment Services Limited | Professional & scientific | 2010 |
| Valley Shuttles Limited | Transport & logistics | 2020 |
| Valleys Groundworks & Civils Limited | Construction | 2025 |
| Valleys Resin Ltd | Construction | 2024 |
| Vanatic Ltd | Wholesale & retail | 2007 |
| Vape for Life Electronic Cigarette Specialists Ltd | Wholesale & retail | 2015 |
| Vasybeb Ltd | Transport & logistics | 2022 |
| Vaynor Properties Limited | Real estate | 1996 |
| VC Industrial Doors Ltd | Manufacturing | 2009 |
| VC Industrial Holdings Limited | Manufacturing | 2026 |
| Vcdrivingservices Ltd | Transport & logistics | 2024 |
| Vecs Aerospace Limited | Wholesale & retail | 2020 |
| Vectar Limited | Manufacturing | 2023 |
| Vennercrest Limited | Real estate | 1980 |
| Venture Cymraeg Limited | Hospitality | 2018 |
| Vertigo Trampoline Park Ltd | Arts & recreation | 2016 |
| VES Recruitment Limited | Administrative & support | 2009 |
| Vibe Fitness Ltd | Arts & recreation | 2009 |
| Victoria House (Merthyr Tydfil) Management Company Limited | Real estate | 2015 |
| Victoria Property (Merthyr Tydfil) Limited | Real estate | 2017 |
| Vintage Plastering Ltd | Construction | 2021 |
| Viper World Ltd | Wholesale & retail | 2023 |
| Vironox Supplements Ltd | Wholesale & retail | 2025 |
| Vision Financial Advisers Ltd | Financial services | 2008 |
| Vision Groundworks and Landscaping Ltd | Construction | 2020 |
| Vision Media UK Ltd | Administrative & support | 2022 |
| Vision Resin Ltd | Manufacturing | 2024 |
| Visual Hair Design Studio Limited | Other services | 2025 |
| VNS Anaesthesia Limited | Health & social care | 2018 |
| Voluntary Action Merthyr Tydfil | Other services | 2007 |
| VT 4YOU Ltd | Other services | 2023 |
| Waitlow Limited | Construction | 2008 |
| Walker & Lewis Estate Agents Ltd | Real estate | 2022 |
| Walker & Lewis Lettings Ltd | Real estate | 2025 |
| Walker Group Employee Pension Trustee Limited | Financial services | 2020 |
| Walker Group Executive Pension Trustee Limited | Financial services | 2020 |
| Wardy Railway Maintenance Limited | Construction | 2016 |
| Warmerhomes S.W Limited | Energy | 2021 |
| Warren Long Rail Solutions Limited | Construction | 2016 |
| Watchlist Finance Limited | Information & communication | 2025 |
| Watkins Development Ltd | Real estate | 2023 |
| Webber Fish Merchants Limited | Wholesale & retail | 2011 |
| Webbers Fish and Chips 2 Limited | Hospitality | 2018 |
| Webbers Fish and Chips Limited | Hospitality | 2016 |
| Weeare Limited | Information & communication | 2016 |
| Welcome to BOZ Ltd | Hospitality | 2025 |
| Welplastering&Maintenance Ltd | Construction | 2021 |
| Welsh Cream Teas Ltd | Wholesale & retail | 2024 |
| Welsh Jewish Cultural Centre | Education | 2024 |
| WET Rooms Direct Ltd | Wholesale & retail | 2011 |
| Whitestone Construction Services Ltd | Professional & scientific | 2022 |
| WHY NOT Shop UK Ltd | Wholesale & retail | 2018 |
| Wilkes Site Services Limited | Mining & quarrying | 2024 |
| Wilkins Wardrobes Ltd | Manufacturing | 2025 |
| Will Thomas Plumbing & Heating Ltd | Construction | 2022 |
| Will Thomas Property Development Ltd | Financial services | 2025 |
| Will-Mor Groundwork Specialists Ltd | Construction | 2021 |
| Williams & Sons Lettings Ltd | Real estate | 2020 |
| Williams Country Supplies Limited | Wholesale & retail | 2014 |
| Williams Decorating Contractors Limited | Construction | 2017 |
| Williams Drainage Contractors Limited | Construction | 2018 |
| Williams Lettings Merthyr Ltd | Real estate | 2023 |
| Winchfawr Holdings Limited | Hospitality | 2006 |
| Winchfawr Investment Limited | Hospitality | 1998 |
| Wing IT Takeaway Ltd | Hospitality | 2026 |
| Wingfield Hotel Limited | Real estate | 2025 |
| Wingmasters PRS Limited | Information & communication | 2025 |
| Wise Nutrition Ltd | Wholesale & retail | 2024 |
| WML Scaffolding Ltd | Construction | 2011 |
| Woodfired MT Ltd | Hospitality | 2019 |
| Woodforce Limited | Extraterritorial | 1985 |
| Woodland Garage Limited | Wholesale & retail | 2002 |
| Woodtech Construction Ltd | Construction | 2023 |
| Worboy Fixers Limited | Manufacturing | 2025 |
| WPP Residential Ltd | Real estate | 2026 |
| Wtbb Ltd | Arts & recreation | 2023 |
| Wykor International Limited | | 1992 |
| Wyndham Arms Merthyr Limited | Hospitality | 2014 |
| Wyrlod DDU Farm Holdings Ltd | Hospitality | 2025 |
| XO Studios Ltd | Information & communication | 2024 |
| Yellow Lemon Trees Ltd | Hospitality | 2025 |
| YMF Property Investment Ltd | Real estate | 2025 |
| Ymlaen Merthyr Tydfil | Administrative & support | 2019 |
| Yourgen Mortgages Ltd | Financial services | 2025 |
| Z Zawijskyj Services Limited | Construction | 2018 |
| Zanders Retail Ltd | Wholesale & retail | 2025 |
| Zikora Havens Ltd | Real estate | 2025 |
| Zirve 68 Ltd | Hospitality | 2026 |