| Wildebeest Publishing Limited | Information & communication | 2003 |
| Wildman Associates Limited | Construction | 2014 |
| Wildwood Glastonbury Limited | Wholesale & retail | 2026 |
| Williams Drain Services Limited | Water & waste | 2016 |
| Williams Properties Management Ltd | Real estate | 2022 |
| Williams Technical Ltd | Professional & scientific | 2024 |
| Willow Daycare Ltd | Health & social care | 2020 |
| Willow Green Sales Ltd | Wholesale & retail | 2025 |
| Willow Holdings (West) Ltd | Administrative & support | 2017 |
| Willpoint Trade PC | | 2019 |
| Windhouse Ltd | Professional & scientific | 2024 |
| Windley Construction Limited | Construction | 2021 |
| Windsor Plumbing and Heating Ltd | Construction | 2025 |
| Wingbeat Limited | Manufacturing | 2014 |
| Wingman Films Ltd | Information & communication | 2003 |
| Winit Competitions Ltd | Arts & recreation | 2023 |
| Winner Investment and Property Ltd | Construction | 2024 |
| WJ Timber Harvesting Ltd | Agriculture & fishing | 2019 |
| Wldldm Limited | Hospitality | 2018 |
| Wolf Works Ltd | Administrative & support | 2025 |
| Wonderful Wellbeing Press Ltd | Information & communication | 2025 |
| Woodbox Interiors Limited | Manufacturing | 2023 |
| Woodniff Ltd | Information & communication | 2024 |
| Woodro Kitchens & Bedrooms Limited | Construction | 2025 |
| Woodsy Limited | Construction | 2022 |
| Woodsy Shopfitting Limited | Construction | 2022 |
| Woofers and Whiskers Ltd | Other services | 2019 |
| World Coffee Club Ltd | Wholesale & retail | 2021 |
| WOW Grafix Ltd | Professional & scientific | 2014 |
| Wright & Pevensey Investments Limited | Real estate | 2025 |
| Wrightway Building Construction Limited | Construction | 2017 |
| Wrightway Holdings Limited | Real estate | 2024 |
| WRT Partners PC | | 2019 |
| Wunderhorse Ltd | Professional & scientific | 2019 |
| Www.Initiativemarket.Com Ltd | Information & communication | 2013 |
| Wyetor Group Ltd | Wholesale & retail | 2026 |
| Wynne and Co Limited | Professional & scientific | 2012 |
| XDV Commerce PC | | 2017 |
| XRG Installations Limited | Construction | 2018 |
| Y Barbican Limited | Hospitality | 2025 |
| Y CAM Cynta' Ltd | Education | 2017 |
| Y Clos Management Company Limited | Real estate | 2015 |
| Y Ffynnon Limited | Wholesale & retail | 2002 |
| Y Llew Coch (Llandybie) CYF | Hospitality | 2018 |
| Y Stand Laeth CYF | Wholesale & retail | 2020 |
| Y Wefan Ltd | Information & communication | 2023 |
| Yasmine-Rose Hairstylist Ltd | Other services | 2021 |
| Yazhi UK Tradelink Limited | Wholesale & retail | 2025 |
| Ydmr Limited | Hospitality | 2024 |
| Ynni Heating Ltd | Construction | 2023 |
| Ynys Ltd | Professional & scientific | 2024 |
| Yokozuna Limited | Wholesale & retail | 2009 |
| Ysgubor Fach Cyfyngedig | Health & social care | 2012 |
| Yvonne Morgan Consultancy Ltd | Professional & scientific | 2022 |
| ZAM Holdings Limited | Real estate | 2025 |
| Zamian Limited | Wholesale & retail | 2020 |
| ZAP Capital Limited | Financial services | 2019 |
| Zara Interiors Limited | Construction | 2009 |
| ZEN Club Ltd | Other services | 2021 |
| Zest Wales Limited | Agriculture & fishing | 2004 |
| Zolly Limited | Hospitality | 2024 |