| Tynevault Ltd | Households | 2025 |
| Typocar Limited | Extraterritorial | 1987 |
| Tyramax Ltd | Construction | 2021 |
| Tyres on the Tyne Ltd | Wholesale & retail | 2025 |
| U Grzegorczyk Ltd | Health & social care | 2016 |
| U Link Digital Limited | Manufacturing | 2024 |
| UAM Property Developments Ltd | Real estate | 2024 |
| Ubrix Ltd | Information & communication | 2023 |
| Ucfne Ltd | Transport & logistics | 2017 |
| Udherana Associates Limited | Health & social care | 2022 |
| Uelevate Ltd | Administrative & support | 2026 |
| Ugly Duckling Renewables Ltd | Manufacturing | 2022 |
| UHC Leisure Ltd | Hospitality | 2019 |
| UHM Limited | Information & communication | 2025 |
| UK Adas Calibration Ltd | Wholesale & retail | 2024 |
| UK Commercial Cleaning Solutions Ltd | Financial services | 2015 |
| UK Commercial Construction Ltd | Construction | 2023 |
| UK Commercial Supplies Limited | Wholesale & retail | 2013 |
| UK Construction Trades Ltd | Professional & scientific | 2026 |
| UK Crushballs Limited | Wholesale & retail | 2021 |
| UK Fibretech Ltd | Information & communication | 2016 |
| UK Fleet Glass Ltd | Wholesale & retail | 2024 |
| UK Food Brokers Ltd | Wholesale & retail | 2024 |
| UK Green Energy Ltd | Professional & scientific | 2026 |
| UK I Build Ltd | Construction | 2025 |
| UK Land Estates (Partnership) Limited | Construction | 2002 |
| UK Land Estates (Services) Limited | Real estate | 2000 |
| UK Land Estates Limited | Construction | 2003 |
| UK Land Estates Partnership (Holdings) Limited | Professional & scientific | 2011 |
| UK Land Investments Limited | Real estate | 2014 |
| UK Lift and Escalator Company Ltd | Manufacturing | 2012 |
| UK Trade Parks Limited | Extraterritorial | 2004 |
| Ukan Propertysolutions Ltd | Real estate | 2024 |
| Ukfirebrand Ltd | Wholesale & retail | 2025 |
| Uklep (2003) Limited | Administrative & support | 2003 |
| Ukles LLP | | 2009 |
| ULA Enterprises Ltd | Wholesale & retail | 2026 |
| Ulookubook Limited | Administrative & support | 2001 |
| Ulookubook Travel Limited | Financial services | 2013 |
| Ultimac Limited | Administrative & support | 2014 |
| Ultimate Hvac Ltd | Construction | 2025 |
| Ultimate Vision Ltd | Wholesale & retail | 2023 |
| Ultra Powder Coatings Limited | Construction | 2006 |
| Ultra Rare Holdings Ltd | Financial services | 2022 |
| Ultra Rare Ltd | Arts & recreation | 2020 |
| Ultrapeak Ltd | Arts & recreation | 2025 |
| Umaart Enterprises Ltd | Wholesale & retail | 2025 |
| Umar's Eatery Ltd | Hospitality | 2015 |
| Umear Ahmad Ltd | Information & communication | 2013 |
| Unbeatable's Afro-Caribbean Stores Ltd | Wholesale & retail | 2025 |
| Under a Tree Media Limited | Professional & scientific | 2012 |
| Unencumbered Pastoral UK Ltd | Wholesale & retail | 2023 |
| Unified Business Communications Limited | Information & communication | 2002 |
| Uniform One Ltd | Manufacturing | 2025 |
| Unify Consultancy Ltd | Professional & scientific | 2022 |
| Union Exchange Limited | Financial services | 2025 |
| Unipark Ltd | Construction | 2025 |
| Unique Natural Products Limited | Health & social care | 2011 |
| Unison Colour Limited | Manufacturing | 2001 |
| Unit 14 Ltd | Other services | 2023 |
| Unit 44 MOT Ltd | Wholesale & retail | 2026 |
| United Property Partners Ltd | Real estate | 2025 |
| Unity Martial Arts Ltd | Wholesale & retail | 2025 |
| Universal Cards & Gifts Ltd | Wholesale & retail | 2014 |
| Universal Home Improvements Limited | Construction | 2012 |
| Universal Productions Limited | Arts & recreation | 2016 |
| Unlimited Skincare Limited | Other services | 2019 |
| Unplugvr Limited | Information & communication | 2024 |
| UP North Media Group Limited | Information & communication | 2019 |
| Uplands Way Consulting Limited | Information & communication | 2022 |
| Upnorth Electrical Maintenance Limited | Construction | 2019 |
| Upnorth Engineering Services Limited | Professional & scientific | 2002 |
| Upnorth Group Limited | Financial services | 2018 |
| Upnorth Response Limited | Extraterritorial | 2012 |
| Uptown Taxi Rentals Ltd | Transport & logistics | 2025 |
| Urban Flower Rooms Limited | Wholesale & retail | 2018 |
| Urban Grafters Ltd | Manufacturing | 2025 |
| Urban Invest Limited | Real estate | 2017 |
| Urmu Ltd | Extraterritorial | 2024 |
| Urology Alliance Limited | Information & communication | 2020 |
| URS Truly Ltd | Wholesale & retail | 2014 |
| Uruk NC Limited | Health & social care | 2019 |
| Urvigna Associates Limited | Health & social care | 2016 |
| USE Less NE Limited | Real estate | 2024 |
| Userve Limited | Administrative & support | 2025 |
| Utility Safety and Environmental Services Ltd | Professional & scientific | 2019 |
| Utto Technologies Limited | Professional & scientific | 2017 |
| Uvend North East Ltd | Wholesale & retail | 2026 |
| V a Properties NE Ltd | Real estate | 2025 |
| V L C Maintenance Services Ltd | Wholesale & retail | 2012 |
| V Thompson Ltd | Professional & scientific | 2024 |
| V Tutuianu Ltd | Health & social care | 2013 |
| V.G.C. Shows Ltd | Arts & recreation | 2019 |
| V.H. BIO Limited | Wholesale & retail | 1991 |
| V.P. Opgtransport Ltd | Transport & logistics | 2026 |
| Vaan Retailing Ltd | Hospitality | 2025 |
| Valceron Group Ltd | Wholesale & retail | 2026 |
| Valente's Bar & Bistro Ltd | Hospitality | 2018 |
| Valentines North East Ltd | Hospitality | 2026 |
| Valerie H Ltd | Other services | 2021 |