| Woodhams Property Holdings Ltd | Real estate | 2025 |
| Woodhouse & Co Limited | Transport & logistics | 2013 |
| Woodies CB Limited | Administrative & support | 2001 |
| Word's OUT Limited | Administrative & support | 1988 |
| Workplace Concepts Limited | Real estate | 2002 |
| Workpool Ltd | Information & communication | 2022 |
| World Sports Economy Ltd | Information & communication | 2026 |
| WSS Events Limited | Extraterritorial | 1989 |
| Wykeham House RTM Company Limited | Households | 2008 |
| XC Resourcing Ltd | Administrative & support | 2023 |
| Xcite Digital Limited | Administrative & support | 2008 |
| Xcite Limited | Administrative & support | 2019 |
| Xero Accountants Limited | Professional & scientific | 2012 |
| Xsell Solution Ltd | Administrative & support | 2014 |
| XTREME1080 Limited | Information & communication | 2014 |
| YEW Barton Court Limited | Households | 2005 |
| YO Network Services 2 Limited | Information & communication | 2024 |
| Your Edit Ltd | Health & social care | 2025 |
| Your Front Door PLC | Professional & scientific | 2003 |
| Your Home Your Floor Ltd | Construction | 2023 |
| Your Keys and Protection Ltd | Financial services | 2019 |
| Your Local Customers Limited | Professional & scientific | 2021 |
| Your Organised Home Ltd | Other services | 2020 |
| Youth Ultimate UK Limited | Wholesale & retail | 2025 |
| Zars Media Ltd | Administrative & support | 2012 |
| Zayes & Hestur Ltd | Real estate | 2024 |
| Zazzie Ltd | Wholesale & retail | 2019 |
| Zeam Markets Limited | Financial services | 2024 |
| Zebon Consulting Services Limited | Professional & scientific | 2021 |
| Zebon Developments Limited | Real estate | 2005 |
| ZEL Consulting Ltd | Information & communication | 2020 |
| Zenchai Fleet Ltd | Wholesale & retail | 2023 |
| Zennergy International Ltd | Construction | 2010 |
| ZES London Limited | Construction | 2018 |
| Zeynab Donya Ltd | Other services | 2025 |
| ZFD Fleet Ltd | Hospitality | 2025 |
| Zibdawn Associates Limited | Real estate | 2001 |
| Zinnea Estates Ltd | Real estate | 2018 |
| Zinnea Technologies Ltd | Information & communication | 2007 |