| Wrenegade Music Limited | Arts & recreation | 2014 |
| Wright Style Engineering Limited | Manufacturing | 2014 |
| Wright Wears Limited | Wholesale & retail | 2015 |
| Writewiseglobal Ltd | Education | 2024 |
| Wrote for Luck Ltd | Wholesale & retail | 2022 |
| WRS Residential Limited | Real estate | 2003 |
| WS Consultants Ltd | Wholesale & retail | 2024 |
| WS Lighting Limited | Professional & scientific | 2012 |
| WT Datatech Ltd | Administrative & support | 2017 |
| WTG Design Limited | Manufacturing | 2018 |
| WTG Services Limited | Manufacturing | 2025 |
| Wtid Limited | Extraterritorial | 2010 |
| Wu-Tsoi's Limited | Real estate | 2025 |
| Wuchia Smartial Limited | Education | 2024 |
| Wunmi Selective Kitchen Ltd | Hospitality | 2022 |
| Wuqijia Massage Centre Ltd | Health & social care | 2018 |
| Wuzo Ltd | Financial services | 2021 |
| WVG Vehicle Sales Ltd | Extraterritorial | 2017 |
| Wychwood Property Strategies Limited | Professional & scientific | 2026 |
| Wycombe Dental Hub Limited | Health & social care | 2021 |
| Wycombe DH Properties Limited | Real estate | 2021 |
| Wyld Fire Arts Limited | Other services | 2024 |
| Wyld Outdoors Ltd | Wholesale & retail | 2024 |
| Wyni Ltd | Wholesale & retail | 2025 |
| Wyse Services Limited | Financial services | 2008 |
| Wysiwyg Ltd | Information & communication | 2018 |
| X Graphics DMI Ltd | Professional & scientific | 2010 |
| X-Case.Co.Uk Limited | Wholesale & retail | 2003 |
| X1BM Limited | Information & communication | 2026 |
| X400 Limited | Administrative & support | 2016 |
| X6 Technology (UK) Limited | Manufacturing | 2024 |
| Xadus Capital Limited | Professional & scientific | 2005 |
| Xadus Consulting Limited | Professional & scientific | 2008 |
| Xadus Investments Limited | Professional & scientific | 2000 |
| Xadus Properties Limited | Real estate | 2014 |
| Xanthe Berkeley Studio Ltd | Information & communication | 2018 |
| Xaser Design Limited | Professional & scientific | 2004 |
| Xcel Group Holdings Limited | Administrative & support | 2017 |
| Xcel Home Kitchen & Bathroom Ltd | Wholesale & retail | 2025 |
| Xcelentra Estate Planning Ltd | Professional & scientific | 2023 |
| Xcelentra Financial Services Limited | Professional & scientific | 2013 |
| Xcelentra Properties Limited | Real estate | 2017 |
| Xcid Technologies Limited | Professional & scientific | 2019 |
| Xclusive Cars Limited | Wholesale & retail | 2023 |
| Xclusive Food Ltd | Hospitality | 2024 |
| Xdriveautos Ltd | Wholesale & retail | 2023 |
| Xeca Limited | Wholesale & retail | 2022 |
| Xeca Services Ltd | Administrative & support | 2024 |
| Xela Automotive UK Ltd | Wholesale & retail | 2025 |
| Xelphi Trading Ltd | Wholesale & retail | 2025 |
| XEN Consultants Ltd | Administrative & support | 2008 |
| Xero (UK) Limited | Information & communication | 2007 |
| Xero Accounting Ltd | Professional & scientific | 2018 |
| Xeroe Limited | Transport & logistics | 2018 |
| Xert IT Services Limited | Real estate | 2011 |
| Xgen Ltd | Professional & scientific | 2025 |
| Xhemi Ltd | Construction | 2016 |
| Xian FU Chen Ltd. | Wholesale & retail | 2025 |
| Xian JIU Chen Ltd. | Wholesale & retail | 2025 |
| Xiang YUN Service Trade Ltd | Wholesale & retail | 2025 |
| Xiaoyang Network Technology Co., Ltd. | Information & communication | 2026 |
| Xingwu Media Co., Ltd | Wholesale & retail | 2025 |
| Xingyun Star Limited | Other services | 2016 |
| Xinovates Ltd | Information & communication | 2025 |
| Xiong Ming LI Ltd. | Wholesale & retail | 2025 |
| Xiong Rise Ltd | Wholesale & retail | 2025 |
| XJ Lettings Ltd | Real estate | 2018 |
| XJ Properties Ltd | Real estate | 2017 |
| XK Central Ltd. | Information & communication | 2018 |
| XL Logistic - Freight Forwarding Limited | Transport & logistics | 2024 |
| XL Refurbishments Limited | Construction | 2025 |
| XL Scaffolding Limited | Construction | 2004 |
| Xlet Limited | Real estate | 2023 |
| XLN Takeaway Ltd | Hospitality | 2017 |
| Xlnc Properties Limited | Real estate | 2017 |
| Xlnc Solutions UK Limited | Information & communication | 2010 |
| Xmanfrank Limited | Real estate | 2022 |
| Xponential Properties Limited | Real estate | 2019 |
| Xpres Taxis Limited | Transport & logistics | 2023 |
| Xpress CC Ltd | Wholesale & retail | 2010 |
| Xpress Coffee Group Limited | Manufacturing | 2011 |
| Xpress Trims Ltd | Other services | 2024 |
| XR Real Estate Ltd | Real estate | 2025 |
| XS FAN Ltd. | Wholesale & retail | 2025 |
| Xscore Solutions Limited | Information & communication | 2025 |
| Xstox Ltd | Wholesale & retail | 2023 |
| Xten Ltd | Information & communication | 2014 |
| Xtend Consulting Ltd | Information & communication | 2018 |
| Xtend Digital Solutions Limited | Information & communication | 2023 |
| Xtend Property Ltd | Real estate | 2023 |
| Xtreme Car Detailing Limited | Wholesale & retail | 2023 |
| Xtreme Motorsport Limited | Manufacturing | 2010 |
| Xtreme Plus UK Limited | Wholesale & retail | 2023 |
| Xtrim MK Limited | Other services | 2024 |
| Xtrim Services Limited | Other services | 2014 |
| XUE WEI KJ Ltd. | Wholesale & retail | 2025 |
| Xurrent Solutions Ltd | Wholesale & retail | 2026 |
| Xxlent Limited | Arts & recreation | 2026 |
| XYZ Lettings Ltd | Households | 2020 |
| XYZ25 Limited | Wholesale & retail | 2002 |