| Witham Truck Wash Ltd | Administrative & support | 2025 |
| Withjamie Limited | Professional & scientific | 2026 |
| WMF Essex Ltd | Manufacturing | 2021 |
| Wood Electrical Limited | Construction | 2017 |
| Woodfield (Residents) Management Limited | Real estate | 2009 |
| Workplace Workforce Solutions Limited | Administrative & support | 2024 |
| Workstylz Ltd | Administrative & support | 2013 |
| World of Delights Limited | Wholesale & retail | 2015 |
| World Software Services Ltd | Information & communication | 2010 |
| World Wide Family of GOD Churches | Other services | 2005 |
| Wormell Motor Works Ltd | Wholesale & retail | 2023 |
| WP Grid Limited | Information & communication | 2019 |
| Wrgutters Limited | Construction | 2025 |
| Wright Trends Limited | Other services | 2017 |
| Wrights Farm Contracts Limited | Agriculture & fishing | 1983 |
| WSA Trans Ltd | Transport & logistics | 2018 |
| Wyldfire Consulting Ltd | Professional & scientific | 2025 |
| XCO5 Publications Limited | Information & communication | 2024 |
| XDS Solutions Ltd | Administrative & support | 2013 |
| Xecuta Ltd | Information & communication | 2024 |
| Xgenuity Limited | Professional & scientific | 2023 |
| XML World Ltd | Information & communication | 2022 |
| XSI Management Limited | Wholesale & retail | 2005 |
| Xsitems Limited | Wholesale & retail | 2005 |
| Xtravaganza Music Limited | Information & communication | 2000 |
| Xtravaganza Operations Limited | Arts & recreation | 2000 |
| Xtravaganza Recordings Ltd. | Administrative & support | 1997 |
| XYZ Insurance Services Ltd | Financial services | 2008 |
| XYZ Premium Finance Limited | Financial services | 2013 |
| YB Retail & Fitness Ltd | Arts & recreation | 2026 |
| Yellow Express Market Ltd | Wholesale & retail | 2026 |
| Yellow Xpress Store Ltd | Wholesale & retail | 2025 |
| Yellowstone ME Investments Ltd | Real estate | 2024 |
| Yems Enterprise Limited | Real estate | 2023 |
| Yeung & Co Limited | Hospitality | 2004 |
| Youmorrow Ltd | Professional & scientific | 2010 |
| Your Brand Agency International Limited | Professional & scientific | 2015 |
| Your CIS Payroll Limited | Professional & scientific | 2026 |
| Your Solar Vision Ltd | Professional & scientific | 2025 |
| Yourstor Essex Limited | Administrative & support | 2024 |
| Yzli Limited | Financial services | 2019 |
| Z-1 Drywall Ltd | Construction | 2021 |
| ZA GAS and Heating Ltd | Energy | 2021 |
| Zaptica Ltd | Information & communication | 2023 |
| Zaravee Ltd | Wholesale & retail | 2021 |
| Zarrah Ltd | Health & social care | 2013 |
| ZD Construction Ltd | Construction | 2019 |
| ZD Consulting Services Limited | Administrative & support | 2016 |
| Zebratech Ltd | Information & communication | 2022 |
| Zedbox East Anglia Limited | Administrative & support | 2017 |
| ZEN Clinic Limited | Health & social care | 2010 |
| ZEN Investment Holdings Limited | Financial services | 2025 |
| ZEN Solutions Ltd | Other services | 2022 |
| Zena Doctors Ltd | Health & social care | 2021 |
| Zena Realty Ltd | Real estate | 2024 |
| Zenosec Limited | Information & communication | 2020 |
| Zerofootprint Limited | Administrative & support | 2009 |
| Zest Product Solutions Limited | Professional & scientific | 2015 |
| Zexi Tech Limited | Extraterritorial | 2025 |
| Ziproh Limited | Administrative & support | 2025 |
| ZOE Alexandria Ltd | Arts & recreation | 2014 |
| ZOG Enterprises Ltd | Real estate | 2014 |
| Zuwa Care Services (UK) Ltd | Health & social care | 2023 |
| ZZ Invest Ltd | Real estate | 2025 |