| Women’S Informal Investing Network Ltd | Other services | 2025 |
| Wood FEN Therapy Limited | Other services | 2013 |
| Woodfen Consultancy Ltd | Professional & scientific | 2012 |
| Woodfen Shavings Ltd | Manufacturing | 2023 |
| Woolbridge Group Ltd | Information & communication | 2025 |
| Woollard Builders Ltd. | Construction | 2018 |
| Wooza Ltd | Professional & scientific | 2025 |
| WOW Tents Glamping Co Limited | Arts & recreation | 2022 |
| WP Collection Ltd | Wholesale & retail | 2025 |
| WP ELY Ltd | Hospitality | 2024 |
| Wpfa Trading Ltd | Hospitality | 2022 |
| Wrights Trading Limited | Professional & scientific | 2001 |
| Wroxton Vantage Ltd | Information & communication | 2022 |
| WS East Anglia Limited | Extraterritorial | 1991 |
| Wyton MOT and Repair Centre Limited | Wholesale & retail | 2022 |
| Wyvern DM Limited | Information & communication | 2004 |
| X Compete Online Ltd | Health & social care | 2024 |
| X10 Beats Ltd | Information & communication | 2021 |
| Xcompete Limited | Arts & recreation | 2018 |
| XCZ Ltd | Administrative & support | 2024 |
| Xett Multimedia Limited | Wholesale & retail | 2007 |
| XEV Limited | Professional & scientific | 2016 |
| XH Bury Limited | Real estate | 2020 |
| Xiasma Limited | Information & communication | 2002 |
| Xionlogic Limited | Professional & scientific | 2011 |
| Xpert Resourcing Limited | Administrative & support | 2016 |
| Xpray Solution Ltd | Administrative & support | 2023 |
| Xpresso Yourself Ltd | Hospitality | 2021 |
| Xtla Holdings Limited | Financial services | 2023 |
| Xtla Limited | Information & communication | 2012 |
| XYZ Properties Ltd | Real estate | 2026 |
| Yado Events & Organizations Ltd | Hospitality | 2019 |
| YAU Haus Architectural Designs Ltd | Professional & scientific | 2025 |
| Yellowspanner Limited | Professional & scientific | 2004 |
| Yeomans Group Business Solutions Ltd | Professional & scientific | 2025 |
| YES EDU UK Ltd | Administrative & support | 2018 |
| Yigit Ltd | Hospitality | 2025 |
| Yohohome Ltd | Real estate | 2024 |
| York Terrace Management Company Limited | Households | 1994 |
| Yorkshire Wollen District Transport Company Limited | Transport & logistics | 2015 |
| Young's Coaches Cambridge Limited | Transport & logistics | 2023 |
| Young's Engineering Cambridge Ltd | Extraterritorial | 2025 |
| Your Security Solutions Limited | Manufacturing | 2015 |
| Your Signature Bathrooms Ltd | Construction | 2019 |
| Yourely Limited | Professional & scientific | 2013 |
| ZAK Construction Limited | Construction | 2000 |
| ZAK Homes Limited | Real estate | 2018 |
| Zapped-Up Electricals Ltd | Construction | 2026 |
| Zeeteck Ltd | Information & communication | 2016 |
| Zeko Education Ltd | Wholesale & retail | 2021 |
| Zellbrook Limited | Real estate | 1989 |
| Zenmen Ltd | Wholesale & retail | 2025 |
| Zilpah Properties Limited | Real estate | 2019 |
| Zilpah Residential Properties Limited | Real estate | 2020 |
| Zinc Plus Limited | Construction | 2018 |
| Ziso Limited | Health & social care | 2017 |
| ZMK Holdings Limited | Financial services | 2024 |
| ZOE Lines Creative Ltd | Professional & scientific | 2024 |
| Zoological International Limited | Extraterritorial | 2025 |
| Æther Solutions Ltd | Health & social care | 2024 |