| WOW Padstow Limited | Wholesale & retail | 2020 |
| Wrfc Services Limited | Wholesale & retail | 2015 |
| Wrhr Ltd | Administrative & support | 2015 |
| Wses Group Ltd | Other services | 2024 |
| Wuachu Ltd | Health & social care | 2011 |
| Wwmaint Ltd | Real estate | 2024 |
| WYC Design Ltd | Information & communication | 2019 |
| WYE Gardens Management Company Limited | Households | 2003 |
| Wysetech Ltd | Manufacturing | 2004 |
| X Kommunications Limited | Information & communication | 2005 |
| Xamigo Limited | Education | 2023 |
| Xcelerate X Ltd | Administrative & support | 2023 |
| XEN Inventory Limited | Information & communication | 2025 |
| Xpress Mini CAB and Rental Ltd | Transport & logistics | 2019 |
| Xtrasoft Limited | Wholesale & retail | 1999 |
| Y2K International Ltd | Professional & scientific | 2019 |
| Yahi Creations Limited | Wholesale & retail | 2023 |
| Yangtze Sunflower Ltd | Hospitality | 2024 |
| Yaro Trans Ltd | Transport & logistics | 2018 |
| Yashina Consulting Limited | Professional & scientific | 2017 |
| Yasmin's Dog and Groom Limited | Agriculture & fishing | 2015 |
| Yellow Crocodile Limited | Professional & scientific | 2018 |
| Yeti Design Services Ltd | Professional & scientific | 2022 |
| Yimba Card Limited | Information & communication | 2022 |
| YL II a Limited | Financial services | 2022 |
| Yoga and Pilates With Katherine Ltd | Arts & recreation | 2022 |
| Yoga Grove Limited | Arts & recreation | 2020 |
| YOM UK Limited | Information & communication | 2024 |
| York Enterprise Ltd | Wholesale & retail | 2025 |
| Yossaya Ltd | Other services | 2017 |
| YOU Select Consultancy Limited | Health & social care | 2009 |
| Youelline Design Services Limited | Professional & scientific | 2017 |
| Your Airhost Ltd | Real estate | 2018 |
| Your Doctor Employee Trust Limited | Health & social care | 2022 |
| Your Doctor Holdings Limited | Financial services | 2021 |
| Your Life Step Ltd | Professional & scientific | 2019 |
| Your Mission Limited | Education | 2013 |
| Your Thyme Limited | Health & social care | 2016 |
| Z&Z Ventures Ltd | Real estate | 2025 |
| Zack & Shavannah Ltd | Real estate | 2022 |
| Zaynak Group Ltd | Administrative & support | 2017 |
| ZEE & Ramay Ltd | Wholesale & retail | 2026 |
| Zegham Abbas Ltd | Wholesale & retail | 2024 |
| Zenith Trading International Ltd | Construction | 2023 |
| Zeppelin Creative Limited | Manufacturing | 2010 |
| Zero Gravity Management Limited | Information & communication | 2019 |
| Zero Line Advanced Research (Zlar) UK Ltd | Administrative & support | 2026 |
| Zeroeast Limited | Professional & scientific | 2021 |
| Zest Management Company Limited | Households | 2003 |
| Zigazig Limited | Construction | 2019 |
| Zimco Ltd | Construction | 2019 |
| Zion Studios Ltd | Professional & scientific | 2019 |
| Zish Capital Limited | Real estate | 2022 |
| Zohreh Property Ltd | Real estate | 2019 |
| Zoom Motors Ltd | Wholesale & retail | 2024 |
| Zoom Technology LLC Ltd | Extraterritorial | 2017 |
| ZS Electrical Berkshire Limited | Construction | 2024 |
| Zyntheon Limited | Professional & scientific | 2025 |