| White Box Digital Ltd | Wholesale & retail | 2023 |
| Whitemist Ltd | Other services | 2023 |
| Whitestile Local Food & Wine Ltd | Wholesale & retail | 2022 |
| Whitestile Local Limited | Wholesale & retail | 2019 |
| Whitewings Property Ltd | Households | 2024 |
| Whps Mechanical Ltd | Construction | 2011 |
| Wild Creative Studio Limited | Information & communication | 2019 |
| Wildcroft Manor Trustee Company Limited | Households | 2000 |
| William Cheung Ltd | Administrative & support | 2014 |
| Windser Road Property Ltd | Real estate | 2022 |
| Windsor BUX Limited | Administrative & support | 2019 |
| Winterlong Ltd | Professional & scientific | 2025 |
| Winthrop Andrews Limited | Manufacturing | 1964 |
| Wise UP TV Ltd. | Information & communication | 2015 |
| Wishingbrook Limited | Administrative & support | 1994 |
| Wist HR Consulting Ltd | Administrative & support | 2024 |
| Wiste Limited | Real estate | 2021 |
| Witchery Pictures Limited | Other services | 2024 |
| Wolven Tech Advisory Ltd | Information & communication | 2025 |
| Wolves UK Bidco Limited | Financial services | 2021 |
| Wolves UK Manco Limited | Financial services | 2021 |
| Woman of Valéur Ltd | Wholesale & retail | 2024 |
| Wonder Key Ltd | Real estate | 2025 |
| Wondersoft Limited | Information & communication | 2019 |
| Word UP Ltd | Professional & scientific | 2011 |
| Work Initiatives Limited | Professional & scientific | 2022 |
| Workout Away Ltd | Hospitality | 2018 |
| World Consulting Solutions Ltd | Wholesale & retail | 2024 |
| World Wise Cars Ltd | Transport & logistics | 2019 |
| Worlds Apart Touring Limited | Information & communication | 1996 |
| Worldwide Innovations Ltd | Wholesale & retail | 2022 |
| WP MIDCO1 Limited | Professional & scientific | 2008 |
| Wraps'N' More Ltd | Hospitality | 2018 |
| Wren Healthcare Group Limited | Financial services | 2019 |
| Wren Healthcare Limited | Health & social care | 2018 |
| WU London Limited | Wholesale & retail | 2018 |
| Xact Motion Ltd | Administrative & support | 2025 |
| Xavi & Co Ltd | Real estate | 2011 |
| Xevioso Ltd | Information & communication | 2024 |
| XG Plastics Ltd | Manufacturing | 2010 |
| XI Plus Ltd | Education | 2024 |
| Xigma Services Ltd | Hospitality | 2020 |
| Xila Ltd | Information & communication | 2025 |
| Xpalm Ltd | Hospitality | 2025 |
| Xstatic Limited | Real estate | 2019 |
| Xtreme Bimmerc Cars Ltd | Wholesale & retail | 2012 |
| Yallahaya Ltd | Other services | 2017 |
| YAM Unity Limited | Health & social care | 2019 |
| Yappley Communications Ltd | Administrative & support | 2016 |
| Yarn by the Water Ltd | Wholesale & retail | 2023 |
| Yarvis Technologies Ltd | Information & communication | 2024 |
| Yayamia Ltd | Wholesale & retail | 2023 |
| Ydfitdrive Ltd | Transport & logistics | 2025 |
| Yellowbox Global Ltd | Information & communication | 2024 |
| Yemenoglu UK Ltd | Wholesale & retail | 2024 |
| Yerky Limited | Real estate | 2024 |
| YES BUT Limited | Information & communication | 2019 |
| Yisen Ltd | Wholesale & retail | 2021 |
| Yoke Group Holdings Ltd | Financial services | 2024 |
| Yoke Propco Ltd | Real estate | 2025 |
| Yomomo Ltd | Wholesale & retail | 2025 |
| Yoneda Ltd | Information & communication | 2024 |
| Yorel Solutions Ltd | Administrative & support | 2023 |
| York Lofts Brentford Management Company Limited | Households | 2003 |
| Yorke Pest Control Limited | Other services | 1998 |
| Young Individuals Count Ltd | Health & social care | 2014 |
| Younglionspiceproductionsmusic Limited | Information & communication | 2020 |
| Your Brolly Limited | Wholesale & retail | 2021 |
| Your Busy Bees Limited | Other services | 2019 |
| Yunes Thobes Ltd | Wholesale & retail | 2023 |
| Z 'N' Z Limited | Health & social care | 2012 |
| Zahavan Ltd | Professional & scientific | 2024 |
| Zaid Auto Ltd | Professional & scientific | 2025 |
| ZAK Building Contractors Limited | Construction | 2015 |
| Zanshin Honya Ltd | Wholesale & retail | 2019 |
| ZAR Executive Cars Ltd | Transport & logistics | 2025 |
| Zawisza Construction Ltd | Construction | 2013 |
| Zayna Wear Ltd | Wholesale & retail | 2021 |
| ZAZ Collection London Ltd | Wholesale & retail | 2020 |
| Zeist Cars Ltd | Wholesale & retail | 2023 |
| Zeist Motors Ltd | Wholesale & retail | 2025 |
| ZEN Real Estate Limited | Real estate | 2024 |
| Zenturiotech Global Limited | Information & communication | 2026 |
| Zero Restaurant Limited | Hospitality | 2023 |
| Zest Search Ltd | Administrative & support | 2021 |
| Zeus Worldwide Co., Ltd | Information & communication | 2020 |
| Zeyra Limited | Information & communication | 2018 |
| Zibby Builders Ltd | Construction | 2025 |
| Zidofy Technology Ltd | Information & communication | 2025 |
| ZMH Maintenance Limited | Construction | 2020 |
| ZMZ Essential Limited | Wholesale & retail | 2025 |
| Znrd Services Ltd | Construction | 2017 |
| ZNZ Estates Ltd | Real estate | 2023 |
| ZT Electronics Ltd | Wholesale & retail | 2026 |
| Zumex Limited | Wholesale & retail | 2024 |
| Ādam Tours Limited | Administrative & support | 2024 |
| Āqil Advisory Limited | Administrative & support | 2025 |