| YCK Properties Limited | Construction | 2018 |
| Yellow Banner Limited | Professional & scientific | 2026 |
| Yellow Crave Cleaning Ltd | Administrative & support | 2025 |
| Yellow Van London Company Limited | Administrative & support | 2012 |
| Yellow Vest Limited | Administrative & support | 2025 |
| Yellowdot Commerce Ltd | Hospitality | 2021 |
| Yemit Services Ltd | Professional & scientific | 2025 |
| Yeses Health Care Ltd | Health & social care | 2025 |
| YEW Interior Designs Ltd | Construction | 2023 |
| YEW Tree Financial Planning Ltd | Professional & scientific | 2009 |
| Yewmaker Ltd | Professional & scientific | 2020 |
| Yewmaker Medicines Ltd | Professional & scientific | 2021 |
| YGR London Ltd | Construction | 2017 |
| Ygrene Heating Ltd | Households | 2021 |
| Yield Developments Ltd | Professional & scientific | 2015 |
| Yield Residential Ltd | Real estate | 2019 |
| Yigou Global Ltd | Transport & logistics | 2023 |
| Yinkuz Healthcare Limited | Administrative & support | 2017 |
| YKJ African and Caribbean Store Limited | Wholesale & retail | 2025 |
| Ylnk Limited | Hospitality | 2019 |
| YLZ Property Ltd | Real estate | 2021 |
| YM Medical Limited | Health & social care | 2025 |
| Yobels Solutions Ltd | Information & communication | 2025 |
| YOJ Ltd | Education | 2026 |
| Yolk Art Ltd | Wholesale & retail | 2025 |
| Yolo IT Services Limited | Information & communication | 2025 |
| Yonah Healthcare Limited | Health & social care | 2016 |
| York Mansions Management Company Limited | Households | 1980 |
| YOU Design Construction Ltd | Construction | 2016 |
| Youmove Property Ltd | Real estate | 2023 |
| Young Coconut Limited | Wholesale & retail | 2021 |
| Young Investing Limited | Administrative & support | 2020 |
| Young Soles Creative Ltd | Manufacturing | 2022 |
| Young's Mechanical Services Limited | Construction | 2017 |
| Your Brand Reach Limited | Information & communication | 2018 |
| Your Cargo Contact Limited | Transport & logistics | 2023 |
| Your E-Com Ltd | Wholesale & retail | 2025 |
| Your Equity Released Limited | Professional & scientific | 2015 |
| Your Great Adventures Ltd | Administrative & support | 2019 |
| Your Great Outdoors CIC | Education | 2025 |
| Your Hospice Lottery Ltd | Arts & recreation | 2013 |
| Your Journey to Freedom Ltd | Professional & scientific | 2019 |
| Your Life Care Solutions Limited | Health & social care | 2011 |
| Your Most Favourite Consultancy Ltd | Professional & scientific | 2024 |
| Your Next Takeaway Limited | Information & communication | 2020 |
| Your Private Broker Limited | Real estate | 2025 |
| Your Provider Healthcare Limited | Transport & logistics | 2024 |
| Your Resourcing Partner Limited | Administrative & support | 2014 |
| Your Short Stays Ltd | Real estate | 2019 |
| Your Smart IT Limited | Wholesale & retail | 2025 |
| Your Workspace Limited | Wholesale & retail | 2018 |
| Your-Group-Uk Ltd | Financial services | 2021 |
| Your-Hospitality-Uk Ltd | Administrative & support | 2021 |
| Yourchoice Accounting Ltd | Professional & scientific | 2024 |
| Youth Football Development Limited | Arts & recreation | 2008 |
| Youyou Services Limited | Real estate | 2025 |
| Yssr Nextgen Tech Ltd | Wholesale & retail | 2025 |
| Yuma Services Limited | Professional & scientific | 2019 |
| Yummy Crumbs Bakery Ltd | Manufacturing | 2024 |
| Yunfei Limited | Households | 2024 |
| Yuse Ltd | Hospitality | 2026 |
| Yvesam Ltd | Health & social care | 2025 |
| Ywis Investment Limited | Real estate | 2025 |
| Z a Barber Ltd | Other services | 2026 |
| Z Cons Trans Limited | Transport & logistics | 2017 |
| Z International Limited | Wholesale & retail | 2017 |
| Z-Zero Design Services Ltd | Information & communication | 2015 |
| Zaca Ltd | Professional & scientific | 2013 |
| Zadeh Consultancy Ltd | Professional & scientific | 2024 |
| Zagan Holdings Limited | Financial services | 2022 |
| Zahra Sahirad Limited | Real estate | 2020 |
| Zamzam Lounge Ltd | Hospitality | 2026 |
| Zanzivair Ltd | Health & social care | 2023 |
| Zapportunity Ltd | Information & communication | 2026 |
| Zara Fish Bar Limited | Hospitality | 2023 |
| Zarben Limited | Information & communication | 2008 |
| Zayrah Healthcare Services Limited | Health & social care | 2022 |
| Zazo Ltd | Health & social care | 2008 |
| Zbbargains Ltd | Wholesale & retail | 2025 |
| ZED Medical Limited | Administrative & support | 2019 |
| ZED Security and Guarding Limited | Administrative & support | 2019 |
| ZEE ZEE M Limited | Construction | 2026 |
| Zeelandia Holdings (UK) Limited | Extraterritorial | 1989 |
| Zeelandia UK Limited | Manufacturing | 1951 |
| Zeku Ltd | Hospitality | 2026 |
| Zemnod Ltd | Transport & logistics | 2024 |
| ZEN Hana Limited | Professional & scientific | 2025 |
| Zenco Plumbing and Heating Ltd | Administrative & support | 2018 |
| Zenrf Ltd | Information & communication | 2024 |
| Zenya Africa Development Ltd | Financial services | 2021 |
| Zeonstar Ltd. | Professional & scientific | 2008 |
| Zephio Ltd | Information & communication | 2025 |
| Zerago Ltd | Administrative & support | 2023 |
| Zero Degrees Limited | Manufacturing | 2023 |
| Zero One East Limited | Professional & scientific | 2024 |
| Zero Tolerance Security Specialists Ltd | Wholesale & retail | 2020 |
| Zest Europe Limited | Professional & scientific | 2005 |
| Zest Exterior Cleaning Ltd | Extraterritorial | 2015 |
| Zest Money Group Ltd | Financial services | 2022 |
| Zettabuy Retail Ltd | Wholesale & retail | 2026 |