| Young Engineer and Scientist Limited | Information & communication | 2025 |
| Young Professionals Group Limited | Hospitality | 2023 |
| Your Agent Ltd | Real estate | 2010 |
| Your Beauty Review Limited | Information & communication | 2020 |
| Your BIZ Solutions Ltd | Information & communication | 2021 |
| Your Building Expert Ltd | Construction | 2009 |
| Your Convenience Store Limited | Wholesale & retail | 2020 |
| Your Digital Partner Ltd | Information & communication | 2017 |
| Your Home Move Limited | Administrative & support | 2024 |
| Your Management Solutions Limited | Arts & recreation | 2007 |
| Your Native Teacher Ltd | Education | 2022 |
| Your New Space Ltd | Real estate | 2022 |
| Your Sign & Display Ltd | Information & communication | 2024 |
| Your Solutions Group Ltd | Professional & scientific | 2025 |
| Your Virtual Advisors Limited | Professional & scientific | 2004 |
| Your Voice Advocacy Project | Health & social care | 1990 |
| Yows 3D Limited | Information & communication | 2018 |
| YR Ysgol Limited | Health & social care | 2016 |
| Yroot Coaching Ltd | Administrative & support | 2026 |
| Ysgol Holdings Limited | Financial services | 2010 |
| Ysgol Pharmacy Limited | Wholesale & retail | 2006 |
| YSI Partners Ltd | Professional & scientific | 2014 |
| Ystalyfera Development Trust | Professional & scientific | 1994 |
| Ystalyfera Rugby Football Club Limited | Arts & recreation | 2016 |
| Ystalyfera Store Limited | Wholesale & retail | 2025 |
| Ystrad Brecon Road Store Ltd | Wholesale & retail | 2023 |
| Ystrad Mynach Developments SPV 1 Ltd | Construction | 2022 |
| Ystradgynlais Community Centre Ltd | Other services | 2020 |
| Yu-Scan Ltd | Information & communication | 2013 |
| Yuen Salon Limited | Other services | 2017 |
| YUEN2 Ltd | Other services | 2022 |
| Yugen Fightwear Ltd | Wholesale & retail | 2026 |
| Yummy Canton Limited | Hospitality | 2023 |
| Yunara Coffee Limited | Manufacturing | 2025 |
| Yuno Supplies Ltd | Manufacturing | 2019 |
| Yuri Development Ltd | Construction | 2019 |
| Z & F Group Limited | Financial services | 2024 |
| Z & F Holdings Limited | Real estate | 2019 |
| Z & F Trading Limited | Hospitality | 2008 |
| Z Broadcast Ltd | Information & communication | 2024 |
| Z Phone Centre Ltd | Wholesale & retail | 2025 |
| Z UGC Solutions Ltd | Wholesale & retail | 2025 |
| Z-Tings Global Ltd | Wholesale & retail | 2025 |
| Zacha Ltd | Wholesale & retail | 2026 |
| Zainab Jaye Artistry Ltd | Other services | 2021 |
| Zakraz Ltd | Hospitality | 2020 |
| Zamaya Services Ltd | Professional & scientific | 2024 |
| Zana Kebab & Pizza Ltd | Hospitality | 2025 |
| Zavance Limited | Hospitality | 2024 |
| Zavh Limited | Wholesale & retail | 2022 |
| Zayinlieva Ltd | Wholesale & retail | 2025 |
| Zeal Developments Ltd | Construction | 2020 |
| Zeal Innovation Ltd | Professional & scientific | 2013 |
| ZED Property Group Ltd | Real estate | 2017 |
| Zeedee Limited | Wholesale & retail | 2026 |
| Zemik Ltd | Construction | 2022 |
| ZEN 8 Ltd | Information & communication | 2019 |
| ZEN Life Marketing Limited | Administrative & support | 2024 |
| ZEN Life Review Ltd | Administrative & support | 2016 |
| Zeneasy Ltd | Wholesale & retail | 2023 |
| Zeneasy Travel Ltd | Transport & logistics | 2025 |
| Zenic Energy Ltd | Energy | 2017 |
| Zenith Motor Factors Limited | Wholesale & retail | 2001 |
| Zenith Umbrella Ltd | Administrative & support | 2012 |
| Zepai Ltd | Information & communication | 2026 |
| Zephyr Tech Solutions Limited | Information & communication | 2023 |
| Zermatt Enterprises Ltd | Wholesale & retail | 2007 |
| Zero Divide Ltd | Wholesale & retail | 2022 |
| Zero Point XR Ltd | Information & communication | 2025 |
| Zero to 100 Ltd | Professional & scientific | 2022 |
| Zeta Alarms Limited | Manufacturing | 1985 |
| Zeus Interiors UK Ltd | Professional & scientific | 2025 |
| ZGHL659 Ltd | Financial services | 2022 |
| Zhang LI Packed Meal Limited | Hospitality | 2021 |
| Ziggy Protect Ltd | Financial services | 2025 |
| Ziloz Co. Ltd | Wholesale & retail | 2019 |
| Zinc IT Ltd | Information & communication | 2018 |
| Zipnet Ltd | Information & communication | 2025 |
| Zippyebay Ltd | Wholesale & retail | 2025 |
| ZJ Property Holdings Limited | Construction | 2023 |
| ZK Passenger Transport Limited | Transport & logistics | 2025 |
| ZLK Homes Limited | Real estate | 2023 |
| ZM Coaching Ltd | Education | 2026 |
| ZM Pro Consulting Ltd | Professional & scientific | 2024 |
| Zmimmigrationservices Ltd | Professional & scientific | 2023 |
| Zminds Consultancy Ltd | Professional & scientific | 2013 |
| Zodiac Media Ltd | Information & communication | 2013 |
| Zodiac Milpro UK Limited | Manufacturing | 2012 |
| Zodiac Recruitment Limited | Administrative & support | 2015 |
| Zoneformat Limited | Construction | 1988 |
| Zoraiz Limited | Hospitality | 2026 |
| ZRV Shellfish Ltd | Wholesale & retail | 2026 |
| ZSC Limited | Information & communication | 2014 |
| Zsolt Paints Ltd | Construction | 2024 |
| ZUG Ground Rents Limited | Real estate | 2025 |
| Zulu Enterprises Limited | Professional & scientific | 2009 |
| Zygo Holdings Limited | Information & communication | 2023 |
| Zylox AI Ltd | Information & communication | 2026 |