| XX Advantage Ltd | Administrative & support | 2018 |
| Xzylon Management Ltd. | Real estate | 2000 |
| Y K Healthcare Limited | Public administration | 2017 |
| Y Stone Limited | Hospitality | 2022 |
| Yaas Real Estate Limited | Real estate | 2020 |
| Yaas Retail Limited | Wholesale & retail | 2023 |
| YAC Camps and Competitions Ltd | Arts & recreation | 2019 |
| Yale Engineers Limited | Wholesale & retail | 1998 |
| YAM Resources Ltd | Professional & scientific | 2007 |
| Yanu Maya Limited | Hospitality | 2025 |
| Yarra Travels Limited | Transport & logistics | 2025 |
| Yateley Construction Properties Limited | Construction | 2003 |
| Yates Build Ltd | Construction | 2022 |
| Yellow Days Active Limited | Health & social care | 2023 |
| Yellow Moon Music Ltd | Education | 2020 |
| Yeti Carpet & Flooring Ltd | Construction | 2024 |
| YII Limited | Real estate | 1998 |
| YKF (London) Limited | Information & communication | 2019 |
| Ynfanteri Ltd | Construction | 2025 |
| YNT Consulting Ltd | Information & communication | 2020 |
| YO Massage Therapy Ltd | Other services | 2024 |
| Yocloud Limited | Information & communication | 2015 |
| Yogdream Limited | Hospitality | 2021 |
| Youngminded Clinical Solutions Ltd | Health & social care | 2022 |
| Your Admissions Ltd. | Other services | 2022 |
| Your FD Consulting Services Limited | Professional & scientific | 2024 |
| Your Garden Guys Ltd | Administrative & support | 2026 |
| Your Gynae Health Ltd | Health & social care | 2019 |
| Your Nanny Network Limited | Education | 2024 |
| Your Personal VA Limited | Administrative & support | 2024 |
| Your Preloved Stories Ltd | Wholesale & retail | 2024 |
| Your Sanctuary | Hospitality | 2010 |
| Your Space Holdings Limited | Financial services | 2025 |
| Your Space Self Storage Limited | Transport & logistics | 2008 |
| Youthdecide Limited | Professional & scientific | 1996 |
| YUM! China Franchising, LP | | 2019 |
| YUM! Europe Holdings, LP | | 2019 |
| YUM! Restaurant Holdings | Financial services | 1997 |
| YUM! Restaurants Europe Limited | Administrative & support | 1974 |
| YUM! Restaurants International Limited | Professional & scientific | 1994 |
| Z Baverstock Ltd | Construction | 2024 |
| Z Production Company Ltd | Information & communication | 2017 |
| Zaha Quality Traders Ltd | Other services | 2024 |
| Zain Consultancy Services (ZCS) Limited | Professional & scientific | 2011 |
| Zaki Consulting Ltd | Other services | 2013 |
| Zamalee Limited | Other services | 2010 |
| ZAP Managed Service Limited | Information & communication | 2009 |
| Zarham Quality Traders Limited | Other services | 2025 |
| Zarim Stanley Ltd | Wholesale & retail | 2013 |
| Zarmes Limited | Professional & scientific | 2012 |
| Zashah Global Limited | Professional & scientific | 2025 |
| ZDD 1 UK Limited | Professional & scientific | 2022 |
| ZED Vault Limited | Wholesale & retail | 2019 |
| ZEE Global Holding Ltd | Financial services | 2024 |
| Zeinab Limited | Health & social care | 2022 |
| Zeletech Limited | Professional & scientific | 2010 |
| ZEN Catering Limited | Hospitality | 2017 |
| ZEN Kuchen Ltd | Wholesale & retail | 2018 |
| Zencast Limited | Real estate | 2009 |
| Zenstone Properties Limited | Real estate | 2024 |
| Zero Knowledge Consulting Limited | Information & communication | 2018 |
| Zest Clean Ltd | Administrative & support | 2023 |
| Zetta Consulting Limited | Professional & scientific | 2023 |
| Zeyzer Ltd | Information & communication | 2025 |
| Zhar Research Ltd | Professional & scientific | 2022 |
| Zhen Spa Limited | Other services | 2019 |
| Zigguratum Limited | Administrative & support | 2023 |
| ZIM Consultants Ltd | Professional & scientific | 2026 |
| Zirconblue Ltd. | Information & communication | 2017 |
| ZNH Limited | Hospitality | 2018 |
| Zoee Travel Services Ltd | Wholesale & retail | 2021 |
| Zohra Engineering Ltd | Professional & scientific | 2024 |
| ZONE3 Ltd | Wholesale & retail | 2009 |
| Zoooming Ltd | Wholesale & retail | 2024 |
| ZRE Investments Limited | Real estate | 2021 |
| ZS IP Consultants Ltd | Information & communication | 2015 |
| ZSS Khawaja Limited | Real estate | 2022 |
| Zulu Mews Company Limited | Households | 2009 |
| Zuluaga & Hardy Group Ltd. | Real estate | 2025 |
| Zumar Halal Meat Ltd | Wholesale & retail | 2024 |