| Wychwood Hot Tubs Ltd | Extraterritorial | 2021 |
| Wychwood Land and Energy Limited | Professional & scientific | 2012 |
| Wyelands Estate Holding Ltd | Real estate | 2019 |
| Wyelands Holdings Limited | Financial services | 2015 |
| Wyelands Limited | Extraterritorial | 1980 |
| WYP Holdings Limited | Health & social care | 2019 |
| X Cubed Limited | Professional & scientific | 2016 |
| XAE (Fitness) Limited | Wholesale & retail | 2021 |
| Xeea Ltd | Wholesale & retail | 2024 |
| Xenata Ltd | Administrative & support | 2024 |
| Xforcesolutions Ltd | Information & communication | 2025 |
| XKE Ltd | Manufacturing | 2025 |
| XPD Print Ltd | Professional & scientific | 2012 |
| XR PR Limited | Professional & scientific | 2016 |
| Xtra Space Storage Limited | Other services | 2007 |
| Xtreme Clean Residential Ltd | Administrative & support | 2024 |
| XV Insight Limited | Administrative & support | 2017 |
| Xvii Services Ltd | Professional & scientific | 2023 |
| Xxvii Management Limited | Wholesale & retail | 2014 |
| Y Super Foods Limited | Hospitality | 2016 |
| Yaal OIL UK Ltd | Wholesale & retail | 2021 |
| Yamato Judo Academy CIC | Education | 2025 |
| Yasmin PCV Driver Solutions Ltd | Transport & logistics | 2017 |
| Yellow Gorilla MFM Ltd | Information & communication | 2020 |
| Yellow Town Properties Ltd | Real estate | 2024 |
| Yellow Wood Energy Consulting Limited | Professional & scientific | 1998 |
| YEMEK18 Ltd | Hospitality | 2025 |
| YES Pleeease Ltd | Wholesale & retail | 2024 |
| Yingfatwong Limited | Hospitality | 2016 |
| Yoku Limited | Professional & scientific | 2023 |
| Yorico Personalisation Services Ltd | Wholesale & retail | 2020 |
| Yorkshire Reactive Power Limited | Energy | 2024 |
| YOS Services Ltd | Wholesale & retail | 2026 |
| Youco UK Ltd | Professional & scientific | 2018 |
| Youneek Productions Ltd | Information & communication | 2017 |
| Young and Sons (Property Development) Ltd | Construction | 2023 |
| Young Life Ltd | Other services | 2023 |
| Your Defence IT Solutions Limited | Professional & scientific | 2016 |
| Your Local Private Investigator Limited | Administrative & support | 2022 |
| Your MUM UX Limited | Information & communication | 2010 |
| Yourtalentrecruiter Ltd | Administrative & support | 2022 |
| Yourwellspace Holdings Ltd | Financial services | 2018 |
| Yourwellspace Ltd | Health & social care | 2017 |
| Yousaf and Sons Ltd | Wholesale & retail | 2025 |
| Ypsilon Delta Investment Limited | Financial services | 2017 |
| YUJ Ltd | Wholesale & retail | 2021 |
| ZAB Consultancy Ltd | Administrative & support | 2022 |
| Zachwood Ltd | Wholesale & retail | 2024 |
| Zacks Barn Events Limited | Administrative & support | 2026 |
| ZAK D Investments Limited | Financial services | 2023 |
| Zaned Properties Limited | Construction | 1998 |
| ZAR2025 Ltd | Hospitality | 2025 |
| Zeall Engineering Limited | Professional & scientific | 2025 |
| ZEN Web Hosting Limited | Information & communication | 2025 |
| Zepiq Ltd | Information & communication | 2026 |
| Zest Information Solutions Limited | Information & communication | 2005 |
| Zestoraa Ltd | Wholesale & retail | 2025 |
| Zeuner Limited | Professional & scientific | 2014 |
| ZIG and Zags Ltd | Wholesale & retail | 2024 |
| Zinnia Hotels Marketing Limited | Hospitality | 2009 |
| Zizery Ltd | Real estate | 2020 |
| Zkibirige Limited | Arts & recreation | 2022 |
| Zmeu Trans Limited | Transport & logistics | 2017 |
| Zoe's Place Trading Limited | Administrative & support | 2015 |
| Zoe's Place Trust | Administrative & support | 2002 |
| Zoomies Mobile VET Care Ltd | Professional & scientific | 2024 |
| Zoop Energy Ltd | Other services | 2020 |
| ZS Design Limited | Professional & scientific | 2016 |
| Zscape Ltd | Professional & scientific | 2022 |
| Zsurgery Ltd | Administrative & support | 2019 |
| Zucconi & Co Holding Limited | Financial services | 2025 |
| Zucconi & Co. Limited | Financial services | 2025 |
| ZZK Ltd | Professional & scientific | 2018 |