| Wrkl Limited | Information & communication | 2008 |
| WRT Piping Solutions Limited | Professional & scientific | 2019 |
| WSA Holdings Limited | Financial services | 2021 |
| WSR Group Ltd | Arts & recreation | 2022 |
| WT Marketing Ltd | Professional & scientific | 2024 |
| WTA Energy Limited | Transport & logistics | 2024 |
| WTA FAR North Limited | Transport & logistics | 2025 |
| WTA Real Estate Ltd | Real estate | 2016 |
| WTA South East Limited | Transport & logistics | 2024 |
| WTA South West Limited | Transport & logistics | 2025 |
| Wumbrella Ltd | Wholesale & retail | 2025 |
| Wumple Limited | Professional & scientific | 2023 |
| WW Cars Limited | Wholesale & retail | 2023 |
| WW Road Trans Ltd | Transport & logistics | 2017 |
| Ww.Prestige Cars Ltd | Wholesale & retail | 2019 |
| Wyboston Car Sales Limited | Wholesale & retail | 2005 |
| Wymer (UK) Limited | Information & communication | 2014 |
| X B S Business Solutions Limited | Professional & scientific | 2000 |
| X7 Ltd | Wholesale & retail | 2026 |
| Xale Consultancy Ltd | Professional & scientific | 2024 |
| Xale Holdings Ltd | Professional & scientific | 2024 |
| Xanthandrus Limited | Professional & scientific | 2010 |
| XD Properties Limited | Real estate | 2021 |
| Xena Renewable Solutions Limited | Construction | 2022 |
| Xhanaj's Ltd | Construction | 2021 |
| Xigen Limited | Administrative & support | 2002 |
| Xiphoid Limited | Information & communication | 2015 |
| Xpeedt Limited | Transport & logistics | 2021 |
| Xpert Bookkeeping Solutions Ltd | Professional & scientific | 2025 |
| Xpress (UK) Limited | Extraterritorial | 1999 |
| Xpress Relocation Limited | Transport & logistics | 1996 |
| Xpress Travel & Transfers Ltd | Financial services | 2020 |
| Xstar Homes Limited | Financial services | 2024 |
| Xsuperbike Limited | Wholesale & retail | 2017 |
| XT Global Ltd | Professional & scientific | 2025 |
| Xtaper Limited | Administrative & support | 2020 |
| Xtmw Limited | Wholesale & retail | 2024 |
| Y & S (Holdings) Limited | Financial services | 2014 |
| Y & Y Wholesale Ltd | Wholesale & retail | 2024 |
| Y S a Property Ltd | Real estate | 2017 |
| Y.I.G Ltd | Real estate | 2022 |
| Y3K Properties Ltd | Real estate | 2024 |
| YA Dangi Ltd | Transport & logistics | 2024 |
| Yaffle Bucknell Limited | Real estate | 2020 |
| Yaffle Estates Limited | Real estate | 2017 |
| Yalocums Ltd | Health & social care | 2011 |
| YAM Global Design Ltd | Professional & scientific | 2021 |
| Yandell Media Group Limited | Professional & scientific | 2001 |
| Yandell Publishing Limited | Information & communication | 1986 |
| Yankey Engineering Ltd | Construction | 2022 |
| Yari Construction Ltd | Construction | 2026 |
| Yari Plumbing and Heating Ltd | Construction | 2022 |
| Yasho Ltd | Professional & scientific | 2013 |
| YAZ360DIGITAL Ltd | Professional & scientific | 2021 |
| Yazco Renewables Ltd | Wholesale & retail | 2022 |
| YC Carpet & Flooring Ltd | Construction | 2026 |
| Yeboah Legacy Group Ltd | Professional & scientific | 2025 |
| Yedu Limited | Wholesale & retail | 2018 |
| Yehorrich Ltd | Transport & logistics | 2025 |
| Yelden Consulting Limited | Professional & scientific | 2019 |
| Yelden Holdings UK Limited | Financial services | 2024 |
| Yello Consulting Ltd | Information & communication | 2020 |
| Yello Group Ltd | Financial services | 2020 |
| Yellowgate HQ Ltd | Professional & scientific | 2026 |
| Yemyom Associates UK Limited | Wholesale & retail | 2025 |
| Yerfis Ltd. | Professional & scientific | 2018 |
| YES at ST Ives Management Company Limited | Households | 2011 |
| YES Property Management LLP | | 2019 |
| Yewtree Advisory Ltd | Professional & scientific | 2023 |
| Yexley Catering Limited | Hospitality | 2017 |
| YHA Cleaning Services Limited | Administrative & support | 2025 |
| Yhden Ltd | Professional & scientific | 2016 |
| Yhden Properties Ltd | Real estate | 2022 |
| YIN Stock Ltd | Wholesale & retail | 2024 |
| YIN Yang Exit Partners Limited | Financial services | 2026 |
| Yizumi UK Limited | Extraterritorial | 2009 |
| Ymar Ltd | Information & communication | 2023 |
| Ymarr Digital Ltd | Other services | 2019 |
| Ymarr Homes Ltd | Real estate | 2019 |
| Ymarr Limited | Hospitality | 2013 |
| YN Healthcare Ltd | Wholesale & retail | 2018 |
| YN Property Management Limited | Households | 2020 |
| Yoga With Lenka Ltd | Education | 2020 |
| Yogic Physio Ltd | Health & social care | 2023 |
| Yolo Consulting Ltd | Professional & scientific | 2022 |
| Yonder Eats Ltd | Hospitality | 2025 |
| Yoreflix Originals [SPV] Limited | Information & communication | 2026 |
| York Close (Flitwick) Management Co. Limited | Households | 2017 |
| York Street Fairs Ltd | Wholesale & retail | 2026 |
| York's Group Limited | Construction | 2012 |
| Yorks Sweeper Hire Limited | Administrative & support | 2010 |
| YOU ARE the Star Limited | Information & communication | 2022 |
| YOU for Coffee Limited | Hospitality | 2023 |
| YOU R Your Best Asset Ltd | Education | 2022 |
| Youdogood Ltd | Professional & scientific | 2026 |
| Young & Co.'s Subsidiary Limited | Professional & scientific | 2006 |
| Young Jackson Limited | Professional & scientific | 2017 |
| Youngs Catering Ltd | Hospitality | 2021 |
| Your Care and Support Limited | Health & social care | 2014 |
| Your Confectionery Limited | Information & communication | 2012 |