| Wyeth House Freehold Management Ltd | Households | 2023 |
| Wykeham Estates (Hampshire) Ltd | Real estate | 2018 |
| Wynwyni Ltd | Wholesale & retail | 2020 |
| Wyvern Events Ltd | Administrative & support | 2019 |
| X1 Drylining Ltd | Construction | 2018 |
| X100 RTW Ltd | Information & communication | 2023 |
| Xavierolivier Monvil Limited | Construction | 2018 |
| Xelgh Limited | Financial services | 2021 |
| Xflow Capital Limited | Professional & scientific | 2018 |
| Xflow Construction Ltd | Construction | 2019 |
| Xflow Developments Limited | Construction | 2020 |
| XLR8 Project Management Consultancy Ltd | Information & communication | 2013 |
| Xobotech Ltd | Administrative & support | 2017 |
| Xploit Technology Holdings Limited | Financial services | 2006 |
| Xploit-Technology Ventures Limited | Information & communication | 2003 |
| Xpression Tile & Stone Ltd | Construction | 2017 |
| XSL Property Limited | Real estate | 2019 |
| Xtravacom Limited | Information & communication | 1997 |
| Xxiiaa Limited | Financial services | 2019 |
| Xyios LLP | | 2019 |
| Xylis Limited | Information & communication | 2023 |
| XYZ Founders Ltd. | Financial services | 2021 |
| XYZ Taverns Ltd | Hospitality | 2024 |
| Xyzzz Limited | Real estate | 2021 |
| Y & M Group Limited | Financial services | 2025 |
| Y M Partnerships Ltd | Arts & recreation | 2022 |
| Y&L Carpentry Ltd | Construction | 2013 |
| Y-Innovation Ltd | Construction | 2021 |
| YA Property Services Limited | Real estate | 2025 |
| Yachtworld International Limited | Information & communication | 2009 |
| Yagmur Grill Ltd | Hospitality | 2026 |
| YAM Kebab Express Ltd | Hospitality | 2023 |
| YAN RS Limited | Hospitality | 2017 |
| Yard Shop Bournemouth Co Ltd | Hospitality | 2025 |
| Yard Shop Brighton Co Limited | Hospitality | 2025 |
| Yard Shop Events Co Limited | Hospitality | 2025 |
| Yard Shop Kitchen Ltd | Hospitality | 2025 |
| Yard Shop Portsmouth Co Ltd | Hospitality | 2025 |
| Yard Shop W1 Co Limited | Hospitality | 2025 |
| Yaseen Fast Food Ltd | Hospitality | 2023 |
| Yash Retail Ltd | Wholesale & retail | 2020 |
| Yasmine Ltd | Wholesale & retail | 2017 |
| YE Partners Limited | Real estate | 2026 |
| Yellow Basket Limited | Professional & scientific | 2019 |
| Yellow Healthcare Ltd | Health & social care | 2025 |
| Yententu Limited | Transport & logistics | 2019 |
| YES I'M a Designer Limited | Professional & scientific | 2013 |
| YES Pink Street Limited | Real estate | 2014 |
| Yessam Limited | Wholesale & retail | 2016 |
| Yetminster Glazing Limited | Construction | 2025 |
| YEZ K Ltd | Real estate | 2023 |
| YLM Planning Ltd | Professional & scientific | 2023 |
| Ynotweldit Limited | Construction | 2018 |
| YOT Swop Limited | Extraterritorial | 2017 |
| YOU Save Moving Limited | Transport & logistics | 2020 |
| YOU Shop WE Drop Ltd | Transport & logistics | 2017 |
| Youaccess Consult Ltd | Health & social care | 2016 |
| Young Ballers Academy Limited | Education | 2025 |
| Young Engineers Nextgen Limited | Education | 2025 |
| Youprint Limited | Professional & scientific | 2009 |
| Your Builder Limited | Construction | 2016 |
| Your PAY Provider Limited | Administrative & support | 2017 |
| Your Physio Plan Ltd | Health & social care | 2013 |
| Your Story IS Everything Limited | Information & communication | 2018 |
| Your Virtual Finance Team Limited | Professional & scientific | 2025 |
| Yourmedpack Limited | Information & communication | 2016 |
| Yousab Limited | Hospitality | 2021 |
| YT International Student Ltd | Education | 2016 |
| YUA Developments Ltd | Professional & scientific | 2026 |
| Yule Industries Ltd | Financial services | 2022 |
| YUM Engineering Ltd | Manufacturing | 2025 |
| YUM Studio Ltd | Hospitality | 2026 |
| Yummy Kitchen (M) Limited | Hospitality | 2016 |
| Yves Mews RTM Company Limited | Households | 2014 |
| YW (P) Limited | Hospitality | 2025 |
| YY House Limited | Hospitality | 2025 |
| YZ Propertyz Limited | Real estate | 2025 |
| Z D Composites Limited | Manufacturing | 2023 |
| Z.J Organic Foods Ltd | Wholesale & retail | 2025 |
| Zahaw Ltd | Other services | 2024 |
| Zaide Pompey Ltd | Hospitality | 2023 |
| ZAK - Freight Limited | Transport & logistics | 2022 |
| Zanelles Limited | Wholesale & retail | 2024 |
| Zaxo Barber Shop Ltd | Other services | 2020 |
| Zaya Corps Ltd | Health & social care | 2025 |
| Zecont Ltd | Transport & logistics | 2025 |
| Zedgy Ltd | Arts & recreation | 2024 |
| Zeefam Ltd | Wholesale & retail | 2026 |
| Zeestay Ltd | Real estate | 2026 |
| Zeeum's Kitchen Ltd | Hospitality | 2024 |
| Zenith Dent Ltd | Health & social care | 2025 |
| Zenrise Realty Limited | Real estate | 2025 |
| Zenterian Streetstyle Limited | Hospitality | 2025 |
| Zephorium Ltd | Manufacturing | 2014 |
| Zephyr Marine Limited | Manufacturing | 2012 |
| Zephyr Property Management Ltd | Real estate | 2011 |
| Zepworth Limited | Real estate | 1977 |
| Zero Carbon Capital Limited | Financial services | 2019 |
| Zest (Southern) Ltd | Real estate | 2008 |
| Zetties Limited | Hospitality | 2017 |