| Wren Pubs Limited | Hospitality | 2015 |
| WRH Solutions Ltd | Construction | 2026 |
| Wright Land and Properties Ltd | Real estate | 2023 |
| Wright Plastering Limited | Construction | 2012 |
| Wright-Zaa Properties Ltd | Real estate | 2025 |
| Wrightmiles Transport and Recovery Ltd | Wholesale & retail | 2025 |
| Wrintis Investments Limited | Real estate | 1959 |
| Writeup Limited | Information & communication | 2026 |
| Wscc Limited | Construction | 2013 |
| WSM Associates EOT Limited | Administrative & support | 2022 |
| WSM Associates Limited | Water & waste | 2002 |
| WSX Hampshire Ltd | Wholesale & retail | 2019 |
| WTA Glazing Limited | Construction | 2014 |
| WTF Electrical Services Ltd | Construction | 2021 |
| Wtsb Limited | Education | 2021 |
| Wurokang International Trading Company Limited | Wholesale & retail | 2020 |
| Wutan International Limited | Arts & recreation | 1994 |
| Wyatt Homeco Ltd | Manufacturing | 2026 |
| Wyatt's Tracks and Blinds Limited | Other services | 2011 |
| Wychwood Park Property Company Limited | Real estate | 2019 |
| Wychwood Projects Ltd | Professional & scientific | 2006 |
| Wyldewood Tree and Garden Ltd | Agriculture & fishing | 2019 |
| Wyldfire Signage Limited | Professional & scientific | 2018 |
| Wylie Contractors Limited | Construction | 2016 |
| Wynberg Retail Limited | Wholesale & retail | 2014 |
| Wyng Property Holdings Ltd | Real estate | 2025 |
| Wynsdale Chase Management Company Limited | Hospitality | 2006 |
| Wynter Road Community Group CIC | Arts & recreation | 2020 |
| Wysa Property Limited | Real estate | 2024 |
| Wyvern House Properties Limited | Construction | 2009 |
| Wüsthof UK Ltd | Manufacturing | 2022 |
| X Machines (Media) Limited | Extraterritorial | 2018 |
| X Machines Limited | Wholesale & retail | 2025 |
| X U Developments Limited | Construction | 2025 |
| X-Press Container Line (UK) Limited | Transport & logistics | 1990 |
| X-Tention Limited | Information & communication | 2019 |
| X-Touch Ltd | Information & communication | 2024 |
| X2 Systems Limited | Information & communication | 1998 |
| X99 Properties Limited | Real estate | 2014 |
| Xalo Ltd | Hospitality | 2024 |
| Xavi-J Limited | Transport & logistics | 2017 |
| Xavier G. Consulting Ltd | Other services | 2013 |
| Xavier G. Medical Aesthetix Limited | Health & social care | 2006 |
| Xebre Limited | Information & communication | 2020 |
| XEL Retail Group Limited | Extraterritorial | 1958 |
| XEN Live Limited | Professional & scientific | 2008 |
| Xenicom Limited | Real estate | 2014 |
| Xerion Healthcare Limited | Professional & scientific | 2015 |
| Xerophyt Ltd | Wholesale & retail | 2024 |
| Xgenera Ltd | Professional & scientific | 2023 |
| Xhalili Property Ltd | Real estate | 2024 |
| Xhavit Zeka Limited | Health & social care | 2021 |
| Xiapps Limited | Information & communication | 2015 |
| XIM Limited | Information & communication | 1999 |
| Xineohp Limited | Transport & logistics | 2025 |
| XK Property Limited | Hospitality | 2025 |
| XK Structures Ltd | Construction | 2020 |
| Xlence Services Ltd | Transport & logistics | 2022 |
| Xlifecycle Limited | Professional & scientific | 2018 |
| XLONEX(2012) Limited | Real estate | 2022 |
| XM Logistics Limited | Transport & logistics | 2021 |
| XM Support Ltd | Health & social care | 2021 |
| Xmanhunt Sneakers Ltd | Wholesale & retail | 2023 |
| XO Group Ltd. | Hospitality | 2017 |
| XO Oxford Street Ltd | Wholesale & retail | 2025 |
| Xoandquin Limited | Manufacturing | 2017 |
| Xoboon Limited | Health & social care | 2025 |
| XSTOP64 Ltd | Professional & scientific | 2023 |
| Xtreme SEO Attacks Ltd | Construction | 2024 |
| Xulo PS Limited | Hospitality | 2022 |
| Xure Solutions Ltd | Information & communication | 2025 |
| Xxai Limited | Information & communication | 2025 |
| Xyberspace Limited | Professional & scientific | 2021 |
| XYZ Investments Ltd | Administrative & support | 2026 |
| Y - Axis United Kingdom Limited | Administrative & support | 2022 |
| Y J Noori Ltd | Real estate | 2022 |
| Y Retail Limited | Construction | 2022 |
| Y.O.D.O. Ltd | Information & communication | 2024 |
| Y.S.Goodman Limited | Transport & logistics | 2019 |
| Y4Y Trading Ltd | Wholesale & retail | 2025 |
| YA Logistics (UK) Limited | Transport & logistics | 2008 |
| Yaabanda Limited | Real estate | 2017 |
| Yacht & Powercraft Design Services Limited | Professional & scientific | 2001 |
| Yacht Boat Parts Limited | Wholesale & retail | 2011 |
| Yacht Crew Services Ltd | Professional & scientific | 2026 |
| Yacht Mayer Limited | Manufacturing | 2017 |
| Yacht Motorboat Services Limited | Transport & logistics | 2024 |
| Yacht Parts Limited | | 1982 |
| Yacht Solar Arches Limited | Manufacturing | 2022 |
| Yachting Sports (U.K.) Limited | Arts & recreation | 1990 |
| Yachtprojects International Ltd | Wholesale & retail | 2013 |
| Yahua Automotive Limited | Manufacturing | 2025 |
| YAK Early Limited | Financial services | 2003 |
| YAK Shack Ltd | Administrative & support | 2025 |
| Yakushi Limited | Other services | 1997 |
| Yala Capital Ltd | Administrative & support | 2024 |
| Yala FX Ltd | Administrative & support | 2025 |
| YAM6 Car Parts Limited | Wholesale & retail | 2021 |
| YAM6 Limited | Wholesale & retail | 2014 |
| YAM6 Marine Limited | Wholesale & retail | 2021 |