| WAM Enterprises Limited | Wholesale & retail | 2016 |
| WAM Holdings Group Ltd | Financial services | 2023 |
| WAM Properties Group Ltd | Real estate | 2023 |
| Want 2 Swim Limited | Education | 2024 |
| Wanwave Ltd | Information & communication | 2024 |
| Ward Simpson Holdings Limited | Real estate | 2025 |
| Ward's Electrical Services Limited | Construction | 2021 |
| Wardchart Limited | Wholesale & retail | 2022 |
| Wardeast Limited | Extraterritorial | 2025 |
| Ware Platform Group Limited | Administrative & support | 2023 |
| Ware Platform Limited | Administrative & support | 2023 |
| Wareham Property Developments Limited | Construction | 2025 |
| Warmer Homes Consultancy Ltd | Construction | 2023 |
| Warrior Teamwear Ltd | Manufacturing | 2022 |
| Wasted Gorilla Ltd | Wholesale & retail | 2023 |
| Water Wings Swim School Ltd | Education | 2016 |
| Waterloo Management Company Limited | Real estate | 2001 |
| Waterstone Mirrors & Frames Ltd | Wholesale & retail | 2016 |
| Waterton Management Company Limited | Households | 2017 |
| Waterton Park Building C and E Management Company Limited | Real estate | 2007 |
| Waterton Park Buildings and Estates Manco Limited | Real estate | 2007 |
| Watertown Consulting Limited | Professional & scientific | 2020 |
| Wati Trading Ltd | Financial services | 2018 |
| WATKIN12 Limited | Arts & recreation | 2018 |
| WATKIN12 Properties Limited | Real estate | 2018 |
| Watkins Crest Property Ltd | Real estate | 2025 |
| Watkins Menswear Limited | Wholesale & retail | 2002 |
| Watt Watt Ltd | Construction | 2017 |
| Watts & Morgan LLP | | 2003 |
| WAX Gone With Gwen Ltd | Professional & scientific | 2024 |
| WE Npower CIC | Administrative & support | 2022 |
| Wear JL Limited | Wholesale & retail | 2022 |
| Weather & Wool Ltd | Other services | 2020 |
| Web Design People Ltd | Information & communication | 2019 |
| Wedge Ceramics Ltd | Manufacturing | 2025 |
| Weeks Medical Services Ltd | Professional & scientific | 2024 |
| Weeks Work Limited | Professional & scientific | 2005 |
| Weigel Group Limited | Administrative & support | 2023 |
| Weinzweig Group Ltd | Financial services | 2023 |
| Welding Supplies Limited | Professional & scientific | 2021 |
| Wellbeing @ the Workplace Ltd | Professional & scientific | 2023 |
| Wellbeing Path Limited | Health & social care | 2026 |
| Welldeed Limited | Extraterritorial | 2026 |
| Wellrate Limited | Extraterritorial | 2025 |
| Wellsh Brewers Cardiff Ltd | Wholesale & retail | 2016 |
| Wellsy Makeup and Hair Ltd | Arts & recreation | 2013 |
| Welsh Automotive Forum | Administrative & support | 2001 |
| Wern Tarw CA Ltd | Real estate | 2023 |
| Wesmotors Ltd | Transport & logistics | 2025 |
| West Cottage Ltd | Real estate | 2025 |
| West Farm Properties Limited | Hospitality | 2020 |
| Westering Pencoed Limited | Real estate | 2021 |
| Western Leisure and Amusements Limited | Arts & recreation | 1997 |
| Westgate Building Services (South Wales) Limited | Construction | 1996 |
| Westgate House Management (Pembroke) Ltd | Households | 2022 |
| Westgate Property Maintenance Limited | Construction | 2023 |
| Westhelm Limited | Extraterritorial | 2025 |
| Weston SW Limited | Hospitality | 2017 |
| Westplace Granary Limited | Administrative & support | 1989 |
| WEZ Waste Services Ltd | Water & waste | 2023 |
| Wheelz Centre Wales Ltd. | Wholesale & retail | 2016 |
| Whiffen Holdings Limited | Administrative & support | 2011 |
| Whimsical Play Village Limited | Arts & recreation | 2022 |
| White Bear Props Ltd | Arts & recreation | 2024 |
| White Breeze Limited | Construction | 2001 |
| White Grove Travel Ltd | Administrative & support | 2022 |
| White Label Operations Limited | Professional & scientific | 2024 |
| White Rock Property Holdings Ltd | Real estate | 2024 |
| Whiteley Law LLP | | 2011 |
| Whiteridge Lettings Ltd | Real estate | 2024 |
| Whitevale Services Limited | Transport & logistics | 1999 |
| Whitewell Tiling and Plumbing Limited | Construction | 2023 |
| Whoclo Ltd | Wholesale & retail | 2021 |
| Whocult Ltd | Hospitality | 2021 |
| WHY Knott Hire Ltd | Administrative & support | 2024 |
| Wick Transport Services Limited | Administrative & support | 1971 |
| Wick Van Centre Limited | Wholesale & retail | 1989 |
| WIG Fach Property Company Limited | Real estate | 1959 |
| Wiggleys FUN Farm Ltd | Arts & recreation | 2010 |
| Wilcox Financial Planning Ltd | Financial services | 2014 |
| Wild COD Limited | Hospitality | 2023 |
| Wild Roots Outdoor Adventures Wales Ltd | Education | 2025 |
| Wild Trails Wales Ltd | Administrative & support | 2015 |
| Wildkraut UK Ltd | Wholesale & retail | 2025 |
| Wildmill Accident Repair Centre Ltd | Wholesale & retail | 2021 |
| Wildmill Community Life Centre | Other services | 2005 |
| Will Group Wales Limited | Professional & scientific | 2022 |
| William Taylor Transport Services Ltd | Transport & logistics | 2024 |
| Williams Aberhonddu Holdings Limited | Transport & logistics | 2021 |
| Williams Bros Margam Limited | Agriculture & fishing | 2011 |
| Williams BTL Ltd | Real estate | 2025 |
| Williams Engineering Partners Ltd | Professional & scientific | 2024 |
| Williams Hauntycastle Hotel Ltd | Hospitality | 2023 |
| Williams Law Ltd | Professional & scientific | 2022 |
| Williams Mechanical & Safety Construction Services Ltd | Professional & scientific | 2015 |
| Williams Plumbing Heating & GAS Ltd | Construction | 2022 |
| Willian Design Limited | Manufacturing | 1977 |
| Willis Engine Repair Centre (UK) Limited | Professional & scientific | 2016 |
| Willis Mitsui & Co Asset Management Limited | Professional & scientific | 2024 |
| Willow in White Limited | Wholesale & retail | 2016 |