| Worldwide Exotics Limited | Wholesale & retail | 1965 |
| Worth Properties Limited | Real estate | 1973 |
| Worthing Stays Limited | Real estate | 2020 |
| Worthstock Ltd | Real estate | 2024 |
| Wotbox Limited | Wholesale & retail | 2023 |
| WP UX Insights Ltd | Information & communication | 2021 |
| WPD Digital Limited | Information & communication | 2022 |
| WPT Sales Inc Ltd | Wholesale & retail | 2015 |
| Wrapdan Ltd | Other services | 2025 |
| Wraysbury House Limited | Health & social care | 2009 |
| Wrea Green Solar Limited | Energy | 2014 |
| WS Hair Studio Ltd | Other services | 2018 |
| WSE Chapel Hill Limited | Energy | 2013 |
| WSE Malmaynes Hall Limited | Energy | 2013 |
| WSE Rhydypandy Limited | Energy | 2013 |
| WSM3231 Ltd | Other services | 2020 |
| WTH Projects Ltd | Arts & recreation | 2025 |
| Wuttagal Limited | Transport & logistics | 2018 |
| WW Electrical Services UK Ltd | Construction | 2023 |
| Wynott Sharkey Ltd | Extraterritorial | 2012 |
| X-Fun Ltd | Hospitality | 2016 |
| XC Photography UK Ltd | Professional & scientific | 2019 |
| Xenon Technologies Ltd | Professional & scientific | 2024 |
| Xibo Signage Ltd | Information & communication | 2011 |
| Xlux Limited | Wholesale & retail | 2021 |
| XM Books and Accounts Ltd | Professional & scientific | 2021 |
| Xodus Capital Limited | Real estate | 2026 |
| Xodus Enterprise Limited | Real estate | 2023 |
| XP UP Limited | Professional & scientific | 2025 |
| Xpress Commerce Ltd | Wholesale & retail | 2025 |
| XRP to the Moon Baby Ltd | Extraterritorial | 2025 |
| Xtradite Digital Limited | Professional & scientific | 2025 |
| Y.N.D. Vested Limited | Real estate | 2017 |
| Y3MEDICAL Limited | Financial services | 2024 |
| Yanabea Ltd | Information & communication | 2023 |
| Yaseen Properties Ltd | Real estate | 2021 |
| Yasmin Atelier Ltd | Wholesale & retail | 2024 |
| Yates Scaffolding Services Limited | Construction | 2020 |
| Yato Ltd | Professional & scientific | 2023 |
| YB Dental Limited | Health & social care | 2021 |
| Yeastie Boys Pizza Club Ltd | Hospitality | 2023 |
| YEK Development Limited | Construction | 2018 |
| Yelland & Price Ltd | Construction | 2014 |
| Yelland & Price Properties 1 Ltd | Construction | 2024 |
| Yellow ANT Media Limited | Information & communication | 2009 |
| Yellow Cherry Ltd | Arts & recreation | 2006 |
| Yellowbird Training Ltd | Professional & scientific | 2011 |
| Yelo Haus Ltd | Professional & scientific | 2019 |
| YEM Investments Limited | Real estate | 2016 |
| YEM Property Investments Limited | Real estate | 2006 |
| YES & Also Limited | Professional & scientific | 2021 |
| Yesdent Limited | Health & social care | 2018 |
| Yilmaz Alterations Ltd | Other services | 2025 |
| YM Global Nexus Ltd | Wholesale & retail | 2026 |
| Ymca Downslink Group | Health & social care | 1999 |
| Ymca Downslink Group Services Ltd | Hospitality | 1992 |
| Yoga in the Lanes Limited | Education | 2019 |
| Yoga With Olive Limited | Arts & recreation | 2020 |
| Yook Holdings Ltd | Real estate | 2018 |
| York House Wine Ltd | Wholesale & retail | 2012 |
| York House Wines and Groceries Ltd | Wholesale & retail | 2018 |
| Yorklands Management Company Limited | Households | 2002 |
| Yosiba Ltd | Health & social care | 2009 |
| Yotu Architectural Design Studio Ltd | Professional & scientific | 2018 |
| Youjuice Limited | Hospitality | 2014 |
| Young Friends Kindergarten Limited | Education | 2022 |
| Young Friends Nursery Ltd | Education | 2007 |
| Young Friends Property Limited | Real estate | 2022 |
| Young Star Electrical Ltd | Construction | 2015 |
| Your 4 Walls Ltd | Construction | 2014 |
| Your Last Decade Ltd | Health & social care | 2025 |
| Your Life Wills Ltd | Information & communication | 2019 |
| Your Ortho Mentor Limited | Education | 2026 |
| Your Paris Experience Limited | Administrative & support | 2011 |
| Your World Experience Limited | Administrative & support | 2012 |
| YP Ventures Ltd | Education | 2025 |
| YS Ophthalmology Ltd | Health & social care | 2021 |
| YTD Holdings Limited | Financial services | 2025 |
| Yummie Pizza Ltd | Hospitality | 2024 |
| Yummies S.B. Ltd | Wholesale & retail | 2007 |
| Yungbillz Music Ltd | Information & communication | 2025 |
| Yuppies Barber Shop Limited | Other services | 2018 |
| YYZ Group Limited | Financial services | 2021 |
| Z L Garden Design Ltd | Administrative & support | 2014 |
| Zagara Limited | Financial services | 2025 |
| Zaggim Limited | Wholesale & retail | 2011 |
| Zahab Blooms Limited | Wholesale & retail | 2025 |
| Zaid SA Ltd | Real estate | 2026 |
| Zaid WR 2 Ltd | Real estate | 2026 |
| Zaid WR Ltd | Real estate | 2025 |
| Zake Developments Ltd | Financial services | 2024 |
| Zake Energy Storage Systems Ltd | Financial services | 2026 |
| Zake Maidenhead Ltd | Other services | 2025 |
| Zake Sovereign Ltd | Construction | 2025 |
| Zake SPV1 Ltd | Construction | 2026 |
| Zake SPV2 Ltd | Construction | 2026 |
| Zakiewicz Associates Limited | Administrative & support | 1995 |
| Zaltzman Consulting Limited | Professional & scientific | 2019 |
| Zambelli Dental Limited | Health & social care | 2026 |
| Zanati Ltd | Wholesale & retail | 2026 |