| Wright XM Ltd | Professional & scientific | 2025 |
| Wucci Marketing Ltd | Professional & scientific | 2025 |
| Wurqi Capital Limited | Financial services | 2019 |
| Wurqi Limited | Information & communication | 2019 |
| Wurqi Technologies Limited | Information & communication | 2019 |
| WW Global Ltd | Education | 2023 |
| Wyndelcare Healthcare Limited | Health & social care | 2019 |
| Wynnstay Capital Limited | Real estate | 2021 |
| X Credit Hire Limited | Administrative & support | 2015 |
| X-Phoenix Investments Ltd | Real estate | 2021 |
| XBX Building Services Limited | Construction | 2023 |
| Xchangepower Ltd | Construction | 2025 |
| Ximol Ltd | Information & communication | 2022 |
| Xlnt (Choice) Ltd | Extraterritorial | 2025 |
| Xlnt (Health) Limited | Hospitality | 2006 |
| XMA Trading Limited | Wholesale & retail | 2026 |
| Xoom Ltd | Information & communication | 2000 |
| Y&A Ventures Ltd | Hospitality | 2025 |
| Y&D Construction Ltd | Construction | 2023 |
| Y.L Investments Ltd | Financial services | 1999 |
| Yagnapurush Limited | Wholesale & retail | 2022 |
| Yan-Ed Ltd | Health & social care | 2011 |
| Yaprak (Knightsbridge) Limited | Hospitality | 2024 |
| Yaprak (Locks Heath) Ltd | Hospitality | 2024 |
| Yashom Limited | Professional & scientific | 2025 |
| Yazan Motors Ltd | Wholesale & retail | 2026 |
| Yazlee Investments Limited | Construction | 2022 |
| Yeshua Empire (AKA. Y Empire) Ltd | Real estate | 2024 |
| YG Oral Surgery Ltd | Health & social care | 2021 |
| YHD Investments 1 Ltd | Construction | 2023 |
| YHD Investments Ltd | Construction | 2021 |
| Yiandora Investments Ltd | Real estate | 2017 |
| Yiandora Properties Limited | Real estate | 2006 |
| Yield Consult Ltd | Information & communication | 2025 |
| Yield Consultancy Limited | Professional & scientific | 2013 |
| YKM Audiology Ltd | Wholesale & retail | 2024 |
| YKT Health Ltd | Wholesale & retail | 2022 |
| Yoff Security Limited | Administrative & support | 2017 |
| Yolo Communications Limited | Professional & scientific | 2014 |
| Yordanchonik Ltd | Construction | 2014 |
| Yotta Automotive Ltd | Administrative & support | 2026 |
| Yotta Media Labs Limited | Information & communication | 2016 |
| YOU1ST Care Limited | Public administration | 2019 |
| Young Mindfulness Ltd | Education | 2019 |
| Your Consulting Limited | Information & communication | 2007 |
| Your Estates Limited | Real estate | 2023 |
| Your Joy Ltd | Administrative & support | 2020 |
| Your Trips Ltd | Administrative & support | 2024 |
| Yourarchive Limited | Information & communication | 2020 |
| Yourintegration Ltd | Information & communication | 2012 |
| Yoursapna Ltd | Other services | 2003 |
| Yprk Eastcote Ltd | Hospitality | 2025 |
| YS Service Station Limited | Other services | 2018 |
| Ysans Domus Limited | Financial services | 2023 |
| Yugen Studio Limited | Information & communication | 2020 |
| YUM Pizza Eastcote Limited | Hospitality | 2025 |
| Z & N Investments Trading Limited | Financial services | 2021 |
| Z & N Limited | Wholesale & retail | 2011 |
| Z & N Properties Limited | Real estate | 2018 |
| Z-Scan Ltd | Public administration | 2024 |
| Zabs Energy Ltd | Energy | 2016 |
| Zabs Group Ltd | Real estate | 2016 |
| Zabs Properties Ltd | Real estate | 2022 |
| Zaher EYE Care Ltd | Health & social care | 2026 |
| Zaiima Rentals Ltd | Administrative & support | 2023 |
| ZAK Drylining Ltd | Construction | 2015 |
| Zakikhani Vascular Ultrasound Limited | Health & social care | 2026 |
| Zakport Ltd | Information & communication | 2019 |
| Zans Investments Limited | Real estate | 2022 |
| ZAV Projects Limited | Financial services | 2017 |
| Zaxgate Limited | Wholesale & retail | 1977 |
| Zayabon UK Limited | Wholesale & retail | 2007 |
| Zaynqf Ltd | Information & communication | 2025 |
| Zeal Investments Ltd | Real estate | 2018 |
| Zebec Consultancy Services Limited | Professional & scientific | 2022 |
| Zebec Development Services Limited | Extraterritorial | 2022 |
| Zedia Limited | Information & communication | 2003 |
| Zeinab Management Limited | Real estate | 2017 |
| ZEN Resourcing Limited | Other services | 2011 |
| Zenith - Accountants & Tax Advisors Limited | Professional & scientific | 2005 |
| Zenith Global Consultancy Limited | Professional & scientific | 2020 |
| Zenpro Pharma Limited | Professional & scientific | 2022 |
| Zero Carbon House Ltd | Construction | 2012 |
| Zero Seven Assets Ltd | Construction | 2017 |
| Zeros and Ones Ltd | Information & communication | 2024 |
| Zest (Fit) Ltd | Arts & recreation | 2025 |
| Zestpart Ltd | Construction | 2014 |
| Zeus Sports Group Limited | Arts & recreation | 2018 |
| Ziggymart Ltd | Wholesale & retail | 2026 |
| Zillionz Ltd | Information & communication | 2016 |
| Zillionz Properties Limited | Real estate | 2017 |
| Zion London Limited | Financial services | 2026 |
| Zita Bay Limited | Real estate | 2021 |
| Ziyvana Ltd | Wholesale & retail | 2023 |
| Zizi Hair Studio Ltd | Other services | 2018 |
| ZM Health Limited | Health & social care | 2017 |
| ZMT Property Solutions Ltd | Real estate | 2018 |
| Zobu Ltd | Health & social care | 2023 |
| Zobuskin Ltd | Other services | 2025 |
| Zocomotion Ltd | Information & communication | 2017 |