| Word & Vision Limited | Administrative & support | 2000 |
| Work Organizer Limited | Information & communication | 2025 |
| Workalert Limited | Administrative & support | 2023 |
| Working Girl Limited | Wholesale & retail | 1989 |
| Workingprogram Limited | Information & communication | 2006 |
| Works Associates Limited | Real estate | 2006 |
| Works Independent Limited | Professional & scientific | 2006 |
| Workstation 2000 Limited | Information & communication | 1996 |
| World Diplomacy Services Limited | Administrative & support | 2024 |
| World of Spice Limited | Wholesale & retail | 1992 |
| World Technology Limited | Information & communication | 1997 |
| Worldcurry Ltd | Hospitality | 2015 |
| Worldnote Limited | | 1979 |
| Worldroomphoto Ltd | Wholesale & retail | 2024 |
| Worthlocal Limited | Arts & recreation | 1990 |
| Worthy Data Services Limited | Professional & scientific | 1996 |
| Worzel Limited | Hospitality | 2016 |
| Wosa Healthcare Limited | Health & social care | 2025 |
| Woslog Limited | Transport & logistics | 2024 |
| Wotsman Crown Plaza Ltd | Hospitality | 2022 |
| Woven Design Limited | Information & communication | 2007 |
| WOW Fashion Accessories Limited | | 1987 |
| WOW Mart Ltd | Wholesale & retail | 2026 |
| Wrench & Co Limited | Construction | 1997 |
| Wright Court (Braintree) Residents Association Limited | Households | 1978 |
| Wrightway Construction Services Limited | Construction | 2002 |
| Wrigley Construction Limited | Construction | 2026 |
| Wrise Limited | Wholesale & retail | 2022 |
| Wrlt Limited | Manufacturing | 2020 |
| Wronsk Ltd | Wholesale & retail | 2026 |
| WW Street Kitchen Ltd | Administrative & support | 2016 |
| WY Resin Ltd | Wholesale & retail | 2026 |
| Wyatt Crocker Limited | Wholesale & retail | 1992 |
| Wych Communications Services Ltd | Information & communication | 2004 |
| WZD Media Ltd | Professional & scientific | 2021 |
| X G Robotic Services Limited | Professional & scientific | 2005 |
| X Workss Limited | Wholesale & retail | 2003 |
| X-Stream Clean Ltd | Administrative & support | 2025 |
| Xact Clothing Limited | Professional & scientific | 2001 |
| Xanada Zuri Limited | Health & social care | 2018 |
| Xclusive Cosmetics Limited | Wholesale & retail | 2025 |
| XEN Edge Ltd | Wholesale & retail | 2004 |
| Xiaqiuqiu Trading UK Ltd | Wholesale & retail | 2024 |
| Xlnt Publishing Services Limited | Information & communication | 1997 |
| Xmatag Ltd | Wholesale & retail | 2025 |
| Xoxovapes Ltd | Other services | 2025 |
| XP One Consultants LLP | | 2006 |
| Xpedk Global Group Ltd | Wholesale & retail | 2021 |
| Xportstore Limited | Wholesale & retail | 2023 |
| Xposure Resources UK Limited | Administrative & support | 2018 |
| Xpower Engines Limited | Professional & scientific | 2000 |
| Xsec Limited | Information & communication | 2025 |
| Xswconsulting Ltd | Information & communication | 2026 |
| Xtreme Oasis Limited | Real estate | 2020 |
| Xytrona Group Ltd | Wholesale & retail | 2026 |
| Y NOT Engineering Co. Ltd | Manufacturing | 2026 |
| Yagmur London Limited | Wholesale & retail | 2007 |
| YAI Group Ltd | Wholesale & retail | 2022 |
| Yalehart Limited | | 1984 |
| Yarohq Ltd | Manufacturing | 2026 |
| YAS TAR Developments Ltd | Construction | 2018 |
| YASBU247 Ltd | Wholesale & retail | 2023 |
| Yates Consultancy Limited | | 1989 |
| Yates Developers Limited | Administrative & support | 2007 |
| Yazid Properties Ltd | Real estate | 2017 |
| Yellow Jersey Design Ltd | Professional & scientific | 2003 |
| Yemfem Limited Company Limited | Health & social care | 2014 |
| Yewdale Assets Ltd | Professional & scientific | 2020 |
| Yewdale Employment Ltd | Financial services | 2020 |
| Yilo Services Ltd | Real estate | 2026 |
| Ying Oriental Home Gourmet Limited | Hospitality | 2017 |
| Yinx Ltd | Health & social care | 2021 |
| YKK Construction Ltd | Construction | 2019 |
| Yorsburg Limited | | 1977 |
| You-Nique Mentoring Limited | Professional & scientific | 2025 |
| Younero Ltd | Wholesale & retail | 2025 |
| Young Construction Limited | Construction | 2002 |
| Young Friend Partners Ltd | Professional & scientific | 2002 |
| Youngman Group Limited | Manufacturing | 2005 |
| Youngs & Co Electrical Services Ltd | Construction | 2021 |
| Younus Khan Store Ltd | Wholesale & retail | 2023 |
| Your Ambition | Education | 1985 |
| Your Picture Frames Ltd | Manufacturing | 2006 |
| Yourtravelshop.Com Limited | Administrative & support | 2004 |
| Yourwellbeing Limited | Real estate | 2005 |
| YU Solutions Limited | Information & communication | 2025 |
| YU Studio Limited | Wholesale & retail | 2019 |
| Yupa Thai Restaurant Limited | Hospitality | 2017 |
| Yuvapriyan & Co Ltd | Hospitality | 2025 |
| YVR Technologies Ltd | Information & communication | 2014 |
| Z Coach & Tours Ltd | Transport & logistics | 2017 |
| ZA Helps Ltd | Education | 2020 |
| ZAB Limited | Professional & scientific | 1997 |
| Zabi Ullah Ltd | Wholesale & retail | 2025 |
| Zabiecomconsulting Ltd | Information & communication | 2026 |
| ZAF & Sons Ltd | Hospitality | 2025 |
| ZAH Companies Ltd | Information & communication | 2026 |
| Zahraan Ltd | Wholesale & retail | 2024 |
| Zaht Limited | Construction | 2022 |
| Zainab Zaid Ltd | Wholesale & retail | 2026 |