| WP Post Productions Ltd | Information & communication | 2012 |
| Wranch & Co Ltd | Wholesale & retail | 2024 |
| Wrapstars Ltd | Hospitality | 2020 |
| Wright Prestige Ltd | Other services | 2017 |
| Wright Recruit Limited | Administrative & support | 2023 |
| Wright Waste Disposal Limited | Water & waste | 2025 |
| Wright Worldwide Ltd | Wholesale & retail | 2017 |
| Wroto Ltd | Information & communication | 2023 |
| WS Technology Ltd | Information & communication | 2020 |
| WTT Corporation Limited | Wholesale & retail | 2025 |
| Wuna Limited | Hospitality | 2026 |
| Www.Com Ltd | Information & communication | 1996 |
| Wyld Holdings Ltd | Financial services | 2025 |
| WYV Properties Limited | Construction | 2007 |
| X & C Property Ltd | Real estate | 2024 |
| X-Tech Search Limited | Administrative & support | 2022 |
| X10 Autos Ltd | Wholesale & retail | 2025 |
| Xaas Consulting Ltd | Professional & scientific | 2023 |
| Xcheck Consulting Ltd | Administrative & support | 2023 |
| Xeon Properties Ltd | Real estate | 2023 |
| Xeta Investments Limited | Administrative & support | 2012 |
| XLS Productions Ltd | Administrative & support | 2022 |
| Xolstice Limited | Information & communication | 2008 |
| XOX Group Ltd | Information & communication | 2023 |
| Xpert Business Solutions and Consultancy Ltd | Professional & scientific | 2019 |
| Xpress Freight Solutions Ltd | Transport & logistics | 2024 |
| XYZ Prop Limited | Construction | 2021 |
| Yah'Tsuri Housing Associate and Support Limited | Real estate | 2026 |
| Yahweh Consulting Ltd | Administrative & support | 2010 |
| Yardley Bespoke Limited | Manufacturing | 2018 |
| Yazeli Ltd | Professional & scientific | 2023 |
| Yeardley Ltd | Hospitality | 2022 |
| Yellow LAB Logistics Ltd | Transport & logistics | 2015 |
| YES Contracts Building Services Ltd | Construction | 2013 |
| YES Properties Limited | Real estate | 2015 |
| YES Store & Ship Ltd | Transport & logistics | 2017 |
| Yestee Solutions Limited | Information & communication | 2011 |
| Ylbv Ltd | Professional & scientific | 2022 |
| YLG Aesthetics Limited | Health & social care | 2020 |
| York Road (Maidenhead) Management Limited | Households | 2019 |
| Yorkies Ltd | Hospitality | 2022 |
| Yorkshire Aggregate Recycling Limited | Transport & logistics | 2015 |
| Yorozo Limited | Information & communication | 2019 |
| YOU & I Care Ltd | Health & social care | 2016 |
| YOU and ME Recruitment Ltd. | Administrative & support | 2013 |
| YOU Sandwich Ltd | Hospitality | 2025 |
| Young Entrepreneur Success Ltd | Professional & scientific | 2025 |
| Young Soles Ltd | Manufacturing | 2010 |
| Your Peak Limited | Administrative & support | 2023 |
| Your Sport London Ltd | Education | 2021 |
| Your Voice Coaching Ltd | Professional & scientific | 2026 |
| Yowie Limited | Health & social care | 2003 |
| YP Digital Ltd | Information & communication | 2002 |
| Ytdl Limited | Information & communication | 2012 |
| YU CAI Properties Ltd | Real estate | 2022 |
| Yuksel Handyman Services Ltd | Construction | 2020 |
| Yumbedded Services Ltd | Professional & scientific | 2023 |
| Yupisat Limited | Information & communication | 2017 |
| Yupisat Solutions Limited | Information & communication | 2004 |
| Yvette's House of Wellness Limited | Other services | 2020 |
| YZ Bros Limited | Wholesale & retail | 2022 |
| Z.K.F. Services Ltd | Construction | 2022 |
| ZAB Assets Limited | Real estate | 2017 |
| Zain KAY Limited | Real estate | 2022 |
| Zaphon Ltd | Financial services | 2025 |
| Zaqii Technologies Ltd | Information & communication | 2026 |
| ZBC Lighting Ltd | Construction | 2024 |
| ZD Properties Limited | Real estate | 2024 |
| Zealous Group Ltd | Real estate | 2024 |
| Zebra Graphics Limited | Manufacturing | 2001 |
| Zelidre Management UK Ltd | Information & communication | 2014 |
| ZEN Place Management Company Ltd | Professional & scientific | 2026 |
| ZEN Water Culture | Education | 2023 |
| Zenboost Limited | Administrative & support | 2024 |
| Zeng London Limited | Arts & recreation | 2024 |
| Zenit Investment Limited | Real estate | 2026 |
| Zenith AI Solutions Ltd | Information & communication | 2025 |
| Zenova Distribution Ltd | Financial services | 2020 |
| Zenova Group PLC | Financial services | 2021 |
| Zenova Ltd | Wholesale & retail | 2020 |
| Zenshin Consulting Ltd | Professional & scientific | 2024 |
| Zerda Kebab Limited | Hospitality | 2017 |
| Zeromatic Janitorial Supplies Limited | Wholesale & retail | 1986 |
| Zest Recycle Ltd | Administrative & support | 1997 |
| Zeumaga Limited | Households | 2025 |
| Ziggy Consultancy Limited | Other services | 2025 |
| Zigtagz International Ltd | Administrative & support | 2018 |
| Zion Talent Capital Ltd | Professional & scientific | 2022 |
| ZMX88 Ltd | Transport & logistics | 2025 |
| Zollikon Tate Limited | Information & communication | 2012 |
| ZON Art Group Ltd | Construction | 2023 |
| ZON Modular Ltd | Construction | 2026 |
| Zonvera Ltd | Wholesale & retail | 2026 |
| Zoro Services Ltd | Construction | 2025 |
| Zorway Exim Limited | Wholesale & retail | 2011 |
| Zosimo Ltd | Health & social care | 2020 |
| Zrnutrition Ltd | Professional & scientific | 2025 |
| Zwag Clothing Ltd | Wholesale & retail | 2019 |