| WWH Healthcare Limited | Administrative & support | 2015 |
| Www.Windscreenprotectionfilm.Uk Limited | Wholesale & retail | 2025 |
| WY Technology Ltd | Wholesale & retail | 2024 |
| Wyatt Tech Forge Ltd | Information & communication | 2026 |
| Wycom Ltd | Real estate | 2023 |
| Wyedene Limited | Financial services | 2022 |
| Wyevale UK Limited | Administrative & support | 2020 |
| Wykewood Health Care Limited | Health & social care | 2019 |
| WYL Ltd | Professional & scientific | 2019 |
| Wylde & Moore Limited | Construction | 2002 |
| Wylde Brands Limited | Wholesale & retail | 2005 |
| Wynsor Allen Management Services Limited | Wholesale & retail | 2000 |
| Wynter Systems Ltd | Professional & scientific | 2025 |
| Wyse Sustainability Limited | Professional & scientific | 2021 |
| WYT Corporation Ltd | Financial services | 2026 |
| Wytham Lodge Health Care Limited | Health & social care | 2023 |
| Wyvern Park Skipton Management Company Limited | Real estate | 2022 |
| Wyvern Sports Ltd | Arts & recreation | 2025 |
| X Legal Limited | Professional & scientific | 2024 |
| X Smith Limited | Information & communication | 2024 |
| X-Cap Payments Ltd | Information & communication | 2025 |
| X82 Ltd | Information & communication | 2022 |
| Xacobe Investments Limited | Financial services | 2024 |
| Xafa Brothers Constructions Ltd | Construction | 2021 |
| Xanadu Vega Limited | Arts & recreation | 2014 |
| Xau.Ra Ltd | Hospitality | 2026 |
| XCA (UK) Limited | Administrative & support | 2013 |
| Xcartsy Ltd | Wholesale & retail | 2025 |
| Xcel Insulation Limited | Wholesale & retail | 2025 |
| Xcel Services Ltd | Professional & scientific | 2016 |
| Xcelle Drive Limited | Administrative & support | 2015 |
| Xcellent Union Ltd | Wholesale & retail | 2024 |
| Xcelpay Limited | Professional & scientific | 2021 |
| Xcipi Limited | Real estate | 2015 |
| Xclusive Building Limited | Construction | 2023 |
| Xclusive Customz Limited | Wholesale & retail | 2021 |
| Xclusive Fireplaces Kitchens Limited | Wholesale & retail | 2014 |
| Xclusive Real Estate LLP | | 2024 |
| Xclusive Solutions Ltd | Real estate | 2013 |
| Xcvb Limited | Professional & scientific | 2012 |
| XDS Spark UK Ltd | Professional & scientific | 2023 |
| XE Travel UK Ltd | Transport & logistics | 2025 |
| Xeeko Technology Solutions Ltd | Information & communication | 2019 |
| Xellent Solutions Ltd | Information & communication | 2024 |
| Xenith Property Group Ltd | Construction | 2024 |
| Xenon Financial Consulting Limited | Professional & scientific | 2024 |
| Xentrian Limited | Information & communication | 2013 |
| Xero Degrees Ltd | Wholesale & retail | 2025 |
| Xerode Limited | Professional & scientific | 2026 |
| Xeroseres Ltd | Professional & scientific | 2021 |
| XFL Transport Limited | Transport & logistics | 2024 |
| XH Properties Ltd | Real estate | 2019 |
| XH Technology Ltd | Administrative & support | 2010 |
| XI KIT Design Ltd | Wholesale & retail | 2026 |
| Xianfu Limited | Wholesale & retail | 2019 |
| Xiangxibuluo Ltd | Hospitality | 2023 |
| Xiaozizi Adworks Ltd | Professional & scientific | 2025 |
| XIE Property Ltd | Real estate | 2025 |
| Xilo Hosting Limited | Information & communication | 2026 |
| Xilo Limited | Information & communication | 2007 |
| Ximi Ltd | Wholesale & retail | 2025 |
| Xindong Entertainment Media Limited | Wholesale & retail | 2025 |
| Xingfuujia Trading Ltd | Wholesale & retail | 2025 |
| Xinglong Xinglong Ltd | Hospitality | 2025 |
| Xinli Trading Ltd | Wholesale & retail | 2025 |
| Xixilong Clothes Limited | Wholesale & retail | 2025 |
| XKX Ltd | Manufacturing | 2019 |
| XL Precision Engineering Limited | Manufacturing | 2012 |
| XL Precision Holdings Ltd | Financial services | 2022 |
| Xl-Service Consulting Limited | Administrative & support | 2006 |
| XLB888 Ltd | Real estate | 2020 |
| Xlitas Consulting Limited | Professional & scientific | 2014 |
| Xlratee Ltd. | Professional & scientific | 2025 |
| XO Food Ltd | Hospitality | 2026 |
| Xochipilli Limited | Wholesale & retail | 2023 |
| Xoolon Limited | Information & communication | 2005 |
| Xoom D Ltd | Information & communication | 2020 |
| Xoom Rentals Ltd | Wholesale & retail | 2022 |
| XOS Consulting Ltd | Professional & scientific | 2021 |
| XP19 Ltd | Professional & scientific | 2023 |
| XP5 Ltd | Wholesale & retail | 2018 |
| Xplicit Creative Cakes and Pastries Limited | Hospitality | 2025 |
| Xpress MOT and Car Repairs Ltd | Wholesale & retail | 2012 |
| Xpromt Ltd | Information & communication | 2010 |
| XPS Storage Limited | Transport & logistics | 2025 |
| Xrayz Software Limited | Administrative & support | 2026 |
| Xrovo Ltd | Wholesale & retail | 2020 |
| XRP Investments Ltd | Real estate | 2025 |
| XRT Limited | Extraterritorial | 2018 |
| XS Sport Academy Ltd | Education | 2023 |
| XSB Limited | Information & communication | 2018 |
| Xsys Ltd | Construction | 2015 |
| XTC Discos Limited | Arts & recreation | 2009 |
| Xteem Beautifier Ltd | Professional & scientific | 2025 |
| Xtendit QPS Ltd | Construction | 2021 |
| Xtralien Limited | Professional & scientific | 2014 |
| Xtreeme Tech Ltd | Wholesale & retail | 2025 |
| Xtreme Mobiles (Sheffield) Ltd | Wholesale & retail | 2005 |
| Xtreme Properties (UK) Ltd | Real estate | 2008 |
| Xtreme Properties Limited | Real estate | 2007 |