| WOW Production Ltd | Administrative & support | 2019 |
| WPB Property Ltd | Real estate | 2022 |
| WR Developments Ltd | Construction | 2025 |
| WR Developments Otford Ltd | Construction | 2026 |
| Wrangl Ltd | Information & communication | 2014 |
| Wrap Nation Limited | Administrative & support | 2015 |
| Wrensfield Limited | Professional & scientific | 2016 |
| Written by Emily Limited | Wholesale & retail | 2021 |
| WTN Holdings Ltd | Financial services | 2022 |
| WUU2 Ltd | Professional & scientific | 2024 |
| WYA Group Ltd | Administrative & support | 2020 |
| Wychwood Inns Ltd | Hospitality | 2008 |
| Wycombe Bar Ltd | Hospitality | 2024 |
| WYE Fine Dining Limited | Hospitality | 2025 |
| Wyeth Projects Services Limited | Professional & scientific | 2009 |
| Wyse Decorators Ltd | Construction | 2015 |
| X Inter Ltd | Information & communication | 2026 |
| X-Art.Biz Limited | Information & communication | 2004 |
| Xcaliber Solutions Limited | Real estate | 2003 |
| Xmail Ltd | Transport & logistics | 2024 |
| Xoogler Neoplants LLP | | 2019 |
| Xpeak Global Ltd | Wholesale & retail | 2026 |
| Xpertrade Ltd | Real estate | 2025 |
| XPO Contract Management Ltd | Administrative & support | 2025 |
| Xtream Analytics Ltd | Information & communication | 2013 |
| Xuanwu Estate Ltd | Real estate | 2019 |
| Xviiimuses Ltd | Financial services | 2026 |
| Xzeed Solutions Limited | Information & communication | 2016 |
| YAK YAK Properties Ltd | Real estate | 2018 |
| Yanis Developments Limited | Construction | 2008 |
| Yates Group Holdings Ltd | Financial services | 2024 |
| Yates Property Solutions Ltd | Real estate | 2022 |
| YB Global Services Ltd | Wholesale & retail | 2021 |
| YBK Sparks Electrical Limited | Manufacturing | 2022 |
| Yellow Star 2 Limited | Education | 2026 |
| Yellow Star Limited | Education | 2011 |
| Yellowstone Techmedia Ltd | Administrative & support | 2013 |
| Yesuk Care and Support Services Ltd. | Health & social care | 2015 |
| Yevhenii Vasylevskyi Ltd | Information & communication | 2024 |
| YEW Trades Ltd | Education | 2024 |
| YGJ SPV LLP | | 2022 |
| YM LEE Psychology Services Limited | Professional & scientific | 2025 |
| YMT Projects Limited | Arts & recreation | 2019 |
| YNK Solutions Limited | Professional & scientific | 2024 |
| Yoga Compass Limited | Education | 2016 |
| York Street Twickenham Limited | Construction | 2010 |
| Yoshiga Technologies Limited | Information & communication | 2025 |
| YOU Find Property Limited | Real estate | 2017 |
| YOU Salon (ST Albans) Ltd | Other services | 2022 |
| Youk Tech Limited | Information & communication | 2026 |
| Youkings Limited | Wholesale & retail | 2021 |
| Young Enough Limited | Professional & scientific | 2026 |
| Young People's Puppet Theatre | Education | 2015 |
| Young's MED Global Limited | Wholesale & retail | 2024 |
| Your Community Funeral Service (Hatfield) Limited | Extraterritorial | 2001 |
| Your Community Funeral Service (Welwyn Garden City) Limited | Extraterritorial | 2001 |
| Your Panacea Ltd | Health & social care | 2026 |
| Your World TV (UK) Limited | Information & communication | 2002 |
| Yourmatenick Limited | Administrative & support | 2010 |
| Yousellcars UK Ltd | Wholesale & retail | 2019 |
| Youth Talk Limited | Health & social care | 1997 |
| Yoxall Property Investments Ltd | Real estate | 2024 |
| YPE Limited | Information & communication | 2002 |
| YSH Flooring Ltd | Manufacturing | 2021 |
| YSH Properties Ltd | Real estate | 2020 |
| YSH Warehouse Ltd | Real estate | 2022 |
| Ytsl Recruitment Ltd | Administrative & support | 2015 |
| Yubi Home Limited | Wholesale & retail | 2024 |
| Yuhao LU ML Solutions Ltd | Professional & scientific | 2024 |
| YWR Limited | Real estate | 2015 |
| Z&L Motor Imports Ltd | Wholesale & retail | 2023 |
| Z-Solutions Limited | Health & social care | 2013 |
| Z.V.Services UK Ltd | Professional & scientific | 2020 |
| Zaante Limited | Information & communication | 2010 |
| Zagadat Pawa LLP | | 2021 |
| Zane Transport Limited | Transport & logistics | 2015 |
| Zaneil Limited | Professional & scientific | 2010 |
| Zaras Catering Limited | Hospitality | 2026 |
| Zavari Ltd | Administrative & support | 2026 |
| Zayd Properties Limited | Real estate | 2010 |
| Zaydeen Ltd | Construction | 2020 |
| Zcfx Trading Ltd | Education | 2022 |
| Zebracarbon Limited | Professional & scientific | 2011 |
| ZED Management Ltd | Professional & scientific | 1998 |
| Zedogarage Ltd | Wholesale & retail | 2024 |
| Zedra Inside Pensions Limited | Administrative & support | 2008 |
| Zeebus Ltd | Professional & scientific | 2022 |
| Zenith Building (Flat 13) Limited | Real estate | 2025 |
| Zenlegacy Ltd | Wholesale & retail | 2025 |
| Zentro Consulting Limited | Professional & scientific | 2026 |
| Zephyr Property Ltd | Real estate | 2019 |
| Zeppelin Films Ltd | Information & communication | 2018 |
| Zero Carbon Engineering Limited | Professional & scientific | 2017 |
| Zespri International (United Kingdom) Limited | Wholesale & retail | 1999 |
| Zeta Hydronic Design Ltd | Construction | 2026 |
| ZF Property Holdings Limited | Real estate | 2021 |
| ZFM Property Holdings Limited | Real estate | 2022 |
| Zieseniss Limited | Wholesale & retail | 2001 |
| Zilu Consultancy Limited | Administrative & support | 2022 |
| Zion Nights Limited | Other services | 2021 |