| Uchsoft Limited | Information & communication | 2011 |
| UDH Construction Ltd | Construction | 2025 |
| Ugocc Limited | Administrative & support | 2016 |
| UIX Technologies Ltd | Information & communication | 2018 |
| UK 3D Signs Limited | Manufacturing | 2019 |
| UK Aplan Corporation Ltd | Administrative & support | 2021 |
| UK Boiler Cover Ltd | Other services | 2014 |
| UK East Connection Ltd | Professional & scientific | 2015 |
| UK Electrics (London) Limited | Construction | 2011 |
| UK Home Providers Ltd | Real estate | 2026 |
| UK K Group Ltd | Professional & scientific | 2025 |
| UK Margin Investments Ltd | Professional & scientific | 2020 |
| UK Small Business Services (SBS) Limited | Administrative & support | 2008 |
| UK Swimming Pools Limited | Construction | 2011 |
| UK Vape Lounge Limited | Manufacturing | 2017 |
| UK Visa Applications Limited | Professional & scientific | 2024 |
| Uk-Dukas Logistics Ltd | Wholesale & retail | 2020 |
| Ukbigmax Limited | Professional & scientific | 2021 |
| UKH Consulting Ltd | Professional & scientific | 2021 |
| Ukhaz Ltd | Health & social care | 2025 |
| UKHOMES4U Ltd | Construction | 2021 |
| UKP Medical Consultancy Ltd | Health & social care | 2016 |
| Ukthech Ltd | Information & communication | 2021 |
| ULO Group Ltd | Real estate | 2025 |
| Ultimate Success Limited | Professional & scientific | 2023 |
| Uncle George Painter Ltd | Construction | 2019 |
| Underconstruction (GB) Ltd | Construction | 2014 |
| Underpinning London Limited | Construction | 2012 |
| Underscore Solutions Ltd | Information & communication | 2023 |
| Unicom Seminars Limited | Professional & scientific | 1983 |
| Unifira Ltd | Information & communication | 2025 |
| Unilink House Limited | Real estate | 2008 |
| Uninxt Limited | Education | 2024 |
| Unique Electrical Systems Ltd | Energy | 2017 |
| Unique Global Consulting Ltd | Financial services | 2023 |
| Unique Property Ltd | Real estate | 2025 |
| Unique Star Seed Limited | Health & social care | 2013 |
| Unismart Limited | Administrative & support | 1992 |
| Unistar Holdings Ltd | Other services | 2025 |
| Unitedlife | Other services | 2004 |
| Unitedlife Trading Limited | Wholesale & retail | 2010 |
| Unity Healthcare UK Limited | Health & social care | 2016 |
| Unitynest Holdings Ltd | Real estate | 2024 |
| Universal Decorating Ltd | Construction | 2024 |
| Universal IT Services Limited | Information & communication | 2015 |
| Universal S Lift Ltd | Construction | 2020 |
| Universalsoft Ltd | Information & communication | 2002 |
| Universe Construction Ltd | Construction | 2024 |
| Univida Travel Limited | Administrative & support | 2015 |
| Unlock Nests Ltd | Real estate | 2025 |
| Unlocksupps Ltd | Manufacturing | 2024 |
| Unscripted Stories Limited | Other services | 2026 |
| UP Above Group Limited | Construction | 2022 |
| Upahaar Dance Company Limited | Arts & recreation | 2012 |
| Upapp Ltd | Administrative & support | 2023 |
| Uplands (1996) Limited | Professional & scientific | 1996 |
| Uplift Floor Clean Ltd | Administrative & support | 2024 |
| Upside Ltd | Wholesale & retail | 2020 |
| Upskilled International Limited | Administrative & support | 2023 |
| Upvc Limited | Construction | 1991 |
| Upwards & Outwards Ltd | Construction | 2014 |
| UR Steel Fixing Limited | Construction | 2025 |
| Urban Build Group Ltd | Construction | 2022 |
| Urban Edge Realty Ltd | Real estate | 2025 |
| Urban Interface Dance UK Ltd | Arts & recreation | 2017 |
| Urban Leisure (Reigate) Limited | Hospitality | 2015 |
| Urban Recovery Services Vehicles Ltd | Transport & logistics | 2025 |
| Urban Research Publications Limited | Information & communication | 1995 |
| Urban Retailing Ltd | Wholesale & retail | 2021 |
| Urban Standard FM Ltd | Administrative & support | 2026 |
| Urify Ltd | Health & social care | 2026 |
| Uropa Design Agencies Ltd. | Wholesale & retail | 2011 |
| Uropa Interior Design Ltd | Real estate | 2024 |
| Urosurg Solutions Ltd | Professional & scientific | 2024 |
| Ursuline Preparatory School Wimbledon Trust | Professional & scientific | 2000 |
| Usama Afzal Ltd | Wholesale & retail | 2025 |
| Usama Ecommerce Limited | Wholesale & retail | 2026 |
| Usha Consultancy Services Limited | Information & communication | 2003 |
| USL United Services Limited | Households | 1984 |
| Utitech Service Company Ltd | Information & communication | 2023 |
| Utopyauk Limited | Wholesale & retail | 2017 |
| UX Beauty Services Limited | Other services | 2012 |
| V & D Property Limited | Real estate | 2023 |
| V & M Properties Investment Ltd | Real estate | 2018 |
| V Good Publications Limited | Information & communication | 2016 |
| V Mohan Ltd | Health & social care | 2023 |
| V&K Investment Ltd | Real estate | 2019 |
| V'Ocean Capital UK Ltd | Professional & scientific | 2023 |
| V2R1 Limited | Financial services | 2024 |
| Vaas Services Ltd | Transport & logistics | 2024 |
| VAC Projects Limited | Construction | 2014 |
| VAH Property Ltd | Real estate | 2025 |
| Vaicyon Solutions Ltd | Information & communication | 2026 |
| Vaikai Consultancy Limited | Real estate | 2016 |
| Vajrang Capital Holdings Limited | Financial services | 2026 |
| VAL Holdings Investment Ltd | Real estate | 2022 |
| VAL Property Management LLP | | 2022 |
| Valentina Cleaning & Maintenance Services Limited | Administrative & support | 2013 |
| Valentina Easy Delivery Ltd | Transport & logistics | 2026 |
| Valerie Manor Limited | Health & social care | 2021 |