| Worn OUT West Limited | Wholesale & retail | 2000 |
| Worth Doing Media Limited | Information & communication | 2013 |
| Wound Resolutions Ltd | Health & social care | 2017 |
| WPM Tyres Limited | Wholesale & retail | 2024 |
| Wprom Services Limited | Administrative & support | 2014 |
| Wrap Transport Ltd | Transport & logistics | 2022 |
| Wrightman Group Ltd | Administrative & support | 2026 |
| Wunderkind Recordings Limited | Information & communication | 2020 |
| Wyndcroft Consultancy Ltd | Administrative & support | 2025 |
| Wynwood Capital Ltd | Extraterritorial | 2025 |
| Wynwood Group Ltd | Real estate | 2024 |
| X Space Developments Limited | Construction | 2020 |
| X Squared Capital Limited | Financial services | 2024 |
| Xavier Associates Ltd | Professional & scientific | 2013 |
| XCELER8 Sales Limited | Administrative & support | 2017 |
| XDC Global Networks Ltd | Information & communication | 2018 |
| Xeesaga Limited | Real estate | 2019 |
| Xgenticiq Limited | Information & communication | 2026 |
| Xheison Steel Fixing Ltd | Construction | 2024 |
| Xperience.Fi Trading Ltd | Financial services | 2023 |
| Xtrasure Limited | Administrative & support | 2017 |
| Xyda Limited | Wholesale & retail | 2019 |
| Y Ddraig Goch IT Consulting Ltd | Administrative & support | 2023 |
| Yagni Ltd | Information & communication | 2021 |
| YAL UK Group Limited | Administrative & support | 2025 |
| Yann Heckmann Limited | Administrative & support | 2018 |
| YAO Cook Ltd | Hospitality | 2023 |
| Yardstick Limited | Administrative & support | 2014 |
| YAS Restaurants Ltd | Hospitality | 2024 |
| YAY Rahman UK Ltd | Wholesale & retail | 2025 |
| YDM London Limited | Real estate | 2022 |
| YEA Aydin Ltd | Professional & scientific | 2020 |
| Yellow Butterflies Limited | Professional & scientific | 2025 |
| Yellow Vest Marketing Ltd | Professional & scientific | 2025 |
| Yeovil Eagle Limited | Other services | 2019 |
| Yerto Limited | Hospitality | 2017 |
| Yesodey Hatorah Girls School Limited | Education | 2020 |
| YH Toddle Inn Limited | Education | 2025 |
| Yosemite Holdings Ltd | Professional & scientific | 2021 |
| Young and Chosen Ltd | Financial services | 2025 |
| YP Legal Services Limited | Professional & scientific | 2021 |
| Ytgs Marketing Ltd | Professional & scientific | 2022 |
| Yulan Limited | Administrative & support | 2001 |
| Yuroli Services Ltd | Information & communication | 2021 |
| Yusuf & Fatima Pandor Establishment Ltd | Health & social care | 2026 |
| Z & Z Accountants Limited | Professional & scientific | 2019 |
| Z Academy of Knowledge and Innovation Ltd | Health & social care | 2023 |
| Z&B Building Services Ltd | Construction | 2019 |
| Zaah Investments Ltd | Real estate | 2025 |
| Zaara Foods Limited | Wholesale & retail | 2023 |
| ZAARA11 Ltd | Hospitality | 2018 |
| Zabbar HR Solutions Ltd | Administrative & support | 2020 |
| Zack Emmett Consulting Ltd | Real estate | 2025 |
| Zainexis Ltd | Information & communication | 2026 |
| Zalvryn Textiles Limited | Wholesale & retail | 2023 |
| Zamindar Goods Transport Ltd | Wholesale & retail | 2025 |
| Zaming Limited | Professional & scientific | 2010 |
| Zams Capital Limited | Financial services | 2022 |
| ZAN Shipping Services Limited | Transport & logistics | 2014 |
| Zar-Mah Capital Limited | Real estate | 2017 |
| Zara Lounge Ltd | Hospitality | 2024 |
| Zarwah Developments Limited | Real estate | 2019 |
| Zarwah Scarbrook Limited | Real estate | 2019 |
| Zaytunah Supermarket (Private) Limited | Wholesale & retail | 2025 |
| Zazf Limited | Real estate | 2024 |
| ZB Business Solutions Limited | Professional & scientific | 2013 |
| ZBT Limited | Wholesale & retail | 2017 |
| ZEB Security Solutions Ltd | Administrative & support | 2025 |
| Zeka Property Ltd | Real estate | 2026 |
| ZEN Semiconductor Search Limited | Administrative & support | 2018 |
| Zenoro Ltd | Wholesale & retail | 2025 |
| Zentak Management Limited | Financial services | 2012 |
| Zentris Space Ltd | Real estate | 2018 |
| Zenvoy Ltd | Wholesale & retail | 2026 |
| Zenya Reverie Ltd | Wholesale & retail | 2026 |
| ZFA Accommodation Limited | Hospitality | 2016 |
| ZFA Construction Limited | Construction | 2016 |
| ZFA Group Limited | Financial services | 2012 |
| ZFA Ltd | Real estate | 2010 |
| ZFA Properties Limited | Real estate | 2016 |
| ZH09 Estates Ltd | Real estate | 2021 |
| ZI ZI Holdings Ltd | Administrative & support | 2024 |
| Zichron Ahron Trust Ltd | Health & social care | 2003 |
| Ziezi Limited | Construction | 2023 |
| Zingzee Limited | Other services | 2011 |
| ZIS Logistics Limited | Administrative & support | 2025 |
| Zjoli Vinken Ltd | Professional & scientific | 2023 |
| ZK Optical Consultancy Ltd | Health & social care | 2017 |
| ZK Retail Ltd | Wholesale & retail | 2025 |
| Zorro Plata Ltd | Real estate | 2021 |
| ZR Electronics Ltd | Wholesale & retail | 2026 |
| Zuari Software Limited | Information & communication | 2013 |
| Zueza Ltd | Real estate | 2020 |
| Zuni 5 Star Limited | Real estate | 2022 |
| ZZ Cars Ltd | Wholesale & retail | 2018 |