| Uncle Eddies Ltd | Hospitality | 2016 |
| Under Floor Heating Supply Limited | Construction | 2012 |
| Under Hammer Ltd | Real estate | 2023 |
| Underdog Pet Group Ltd | Wholesale & retail | 2026 |
| UNDERFLOORHEATING1 Limited | Construction | 2009 |
| Underground Plant and Construction Ltd | Administrative & support | 2023 |
| Undertech Trading Limited | Wholesale & retail | 2018 |
| Undisco Ltd | Information & communication | 2023 |
| Unfolding Holdings Limited | Professional & scientific | 2019 |
| Unica Home Care Ltd | Health & social care | 2026 |
| Unights App Limited | Wholesale & retail | 2018 |
| Union Work Services Limited | Administrative & support | 2025 |
| Uniqorn Systems Ltd | Information & communication | 2026 |
| Unique Corner Store Ltd | Wholesale & retail | 2024 |
| Unique Cornwall Limited | Construction | 2024 |
| Unique Frontline Protection Limited | Administrative & support | 2007 |
| Unique Home Pieces Ltd | Extraterritorial | 2024 |
| Unique Living Limited | Construction | 2024 |
| Unique Occasions at Loversall Limited | Hospitality | 2021 |
| Unique Roofing Contractors Limited | Construction | 2021 |
| Unique Tyres Ltd | Wholesale & retail | 2024 |
| Uniquely Social Care Ltd | Health & social care | 2022 |
| Unisign Limited | Professional & scientific | 2018 |
| Unit 15 Fencing and Joinery Services Limited | Extraterritorial | 2014 |
| Unitas Wholesale Limited | Wholesale & retail | 2018 |
| Unite Functional Fitness Ltd | Arts & recreation | 2023 |
| United Apps Ltd | Wholesale & retail | 2022 |
| United Brewing Company Limited | Manufacturing | 2023 |
| United Garments Limited | Wholesale & retail | 2021 |
| United Merchent Ltd | Wholesale & retail | 2025 |
| United Passenger Seating UK Ltd | Wholesale & retail | 2023 |
| United Professionals UK Limited | Professional & scientific | 2000 |
| United Property Services & Rental Ltd | Real estate | 2026 |
| United Salvage Ltd | Wholesale & retail | 2023 |
| Unitee Golf Limited | Manufacturing | 2025 |
| Unity Living Kirk Lane Limited | Construction | 2022 |
| Unity Trade Fusion UK Ltd | Wholesale & retail | 2024 |
| Unity Vault Ltd | Financial services | 2025 |
| Unity Works Living Limited | Construction | 2021 |
| Unityed Ltd | Education | 2025 |
| Unium Bioscience Ltd | Agriculture & fishing | 2017 |
| Universal Coatings (UK) Limited | Construction | 2009 |
| Universal Phil Holdings Limited | Financial services | 2020 |
| Universal Restoration Limited | Construction | 2023 |
| Universal UK MOT Ltd | Administrative & support | 2017 |
| Univex Limited | Other services | 1993 |
| Uniworld Dynamic Ltd | Wholesale & retail | 2024 |
| Uniworld Foods Limited | Wholesale & retail | 2023 |
| Uniworld Foods Services Ltd | Wholesale & retail | 2024 |
| Uniworld Import and Export Ltd | Wholesale & retail | 2024 |
| Uniworld Packages Ltd | Other services | 2024 |
| Unknown Apparel Ltd | Wholesale & retail | 2020 |
| Unleashed Ltd | Administrative & support | 2016 |
| Unmasked Trading Ltd | Wholesale & retail | 2023 |
| Unstoppable Inc Ltd | Education | 1997 |
| Untold Kitchens&Bedrooms Ltd | Construction | 2026 |
| Unvented Cylinder Specialist Ltd | Construction | 2018 |
| Unyfun Ltd Limited | Transport & logistics | 2026 |
| UP a Tree Limited | Administrative & support | 2006 |
| UP Yours! Collective Ltd | Arts & recreation | 2026 |
| Uplbs Limited | Information & communication | 2024 |
| Upmotor Ltd | Wholesale & retail | 2024 |
| UPP Wellbeing Ltd | Wholesale & retail | 2020 |
| Uprise Digital Ltd | Manufacturing | 2019 |
| Upscale Interior Coatings Ltd | Construction | 2019 |
| Upson Property Enterprises Limited | Real estate | 2015 |
| UPT Holding Ltd | Financial services | 2018 |
| Upwright Scaffolding & Access Ltd | Construction | 2026 |
| UR Foods Limited | Hospitality | 2025 |
| Urban Arborist Ltd | Agriculture & fishing | 2017 |
| Urban Burgers Group Limited | Hospitality | 2015 |
| Urban Burgers Limited | Hospitality | 2017 |
| Urban Construction Limited | Construction | 2023 |
| Urban Hedges Limited | Wholesale & retail | 2023 |
| Urban Hygiene Limited | Wholesale & retail | 2003 |
| Urban Lantern Studios Ltd | Extraterritorial | 2026 |
| Urban Light Developments Ltd | Real estate | 2005 |
| Urban Living Ltd | Real estate | 2025 |
| Urban Midco Limited | Hospitality | 2024 |
| Urban Move Group Ltd | Professional & scientific | 2025 |
| Urban Parcel Ltd | Wholesale & retail | 2024 |
| Urban Restaurants Group Ltd | Hospitality | 2025 |
| Urban Solz Ltd | Wholesale & retail | 2025 |
| Urban Staff Ltd | Hospitality | 2013 |
| Urban Titanium Ltd | Information & communication | 2022 |
| Urban Topco Ltd | Financial services | 2025 |
| Urban Village Ltd | Administrative & support | 2023 |
| Urban Village Tradeco Ltd | Professional & scientific | 2025 |
| Urbanaxis Construction Site Ltd | Extraterritorial | 2026 |
| Urbanelm Services Ltd | Extraterritorial | 2026 |
| Urbanluxcars Ltd | Wholesale & retail | 2026 |
| Urbanpulse Media Ltd | Extraterritorial | 2025 |
| Urbanpulse Technology Ltd | Extraterritorial | 2026 |
| Urbanrise Creative Ltd | Extraterritorial | 2025 |
| Uris Group Limited | Financial services | 1990 |
| Urocare Solutions Ltd | Health & social care | 2025 |
| URS Global Properties Ltd | Real estate | 2024 |
| Ursul Limited | Transport & logistics | 2017 |
| Ursus Transport Ltd | Transport & logistics | 2023 |
| Urth Films Limited | Arts & recreation | 2019 |