| UK Capacity Reserve Limited | Energy | 2014 |
| UK Car Hire Teesside Ltd | Administrative & support | 2026 |
| UK Claims N E Ltd | Information & communication | 2020 |
| UK Computers Ltd | Wholesale & retail | 2017 |
| UK Energy Reserve Limited | Energy | 2016 |
| UK Estate Agent Signs Limited | Administrative & support | 2019 |
| UK Everydog Ltd | Manufacturing | 2026 |
| UK Mobile Solutions (NE) Limited | Wholesale & retail | 2020 |
| UK Pharmacuticals Limited | Health & social care | 2018 |
| UK Plant Traders Limited | Professional & scientific | 2012 |
| UK Pods Limited | Manufacturing | 2016 |
| UK Power Reserve (Asfordby) Limited | Energy | 2011 |
| UK Power Reserve (Monckton Road) Limited | Energy | 2010 |
| UK Power Reserve (Trumfleet) Ltd | Energy | 2009 |
| UK Power Reserve Limited | Energy | 2010 |
| UK Safety Professionals (NE) Ltd | Professional & scientific | 2010 |
| UK Student Visa Assist Limited | Education | 2025 |
| UK Top Influencer Academy CIC | Education | 2025 |
| UK Top Influencer Ltd | Professional & scientific | 2023 |
| UK Utility Reserve Limited | Energy | 2017 |
| Ukemi Care Limited | Professional & scientific | 2025 |
| Ukfra Limited | Professional & scientific | 2026 |
| Ukra Limited | Wholesale & retail | 2020 |
| Ukraine House CIC | Wholesale & retail | 2026 |
| Uktec Ltd | Professional & scientific | 2024 |
| Ultimate Windows North Limited | Construction | 2024 |
| Ulysses Fitness and Nutrition Ltd | Arts & recreation | 2016 |
| Umadevi Mart Ltd | Wholesale & retail | 2025 |
| Umadevi Overseas Consultancy Limited | Information & communication | 2024 |
| Umadevi Retail Limited | Wholesale & retail | 2023 |
| Umbrella Hugs CIC | Administrative & support | 2022 |
| Umbuilders Ltd | Construction | 2025 |
| Umer Draze Ltd | Wholesale & retail | 2020 |
| UMI Oriental Food Limited | Hospitality | 2016 |
| Umiya Heating Solution Limited | Construction | 2026 |
| Unasys Limited | Professional & scientific | 2000 |
| Undergo Ltd | Hospitality | 2024 |
| Uni-Locum Limited | Professional & scientific | 2015 |
| Unicorn Digital Limited | Information & communication | 2025 |
| Unifit Raincovers Limited | Manufacturing | 1996 |
| Unihub Solutions Limited | Professional & scientific | 2023 |
| Unique Bites Ltd | Hospitality | 2025 |
| Unique Clean-Ique Ltd | Administrative & support | 2021 |
| Unique Conservatory Roofs Ltd | Construction | 2003 |
| Unique Cooking Ltd | Hospitality | 2023 |
| Unique Electrical and Renewables Ltd | Construction | 2024 |
| Unique Electrics (NE) Ltd | Construction | 2025 |
| Unique Electrics Ltd | Construction | 2018 |
| Unique Living Teesside Limited | Households | 2022 |
| Unique Luxury Homes Ltd | Hospitality | 2026 |
| Unique Properties North East Ltd | Real estate | 2023 |
| Unique Square Ltd | Wholesale & retail | 2025 |
| Uniqueyig@Middlesbrough Ltd | Wholesale & retail | 2021 |
| United Engineers NE Ltd | Manufacturing | 2024 |
| United Kingdom Development Corporation Ltd | Construction | 2020 |
| United Kingdom Group Ltd | Financial services | 2024 |
| United Kingdom Technology Corporation Ltd | Information & communication | 2023 |
| United Solar Power Energy Limited | Manufacturing | 2024 |
| United Suppliers Ltd | Wholesale & retail | 2024 |
| Unitel Contact Centres Limited | Information & communication | 2014 |
| Unity Digital Technologies Ltd | Information & communication | 2018 |
| Unity GPO Ltd | Wholesale & retail | 2016 |
| Unity Network Technologies Ltd | Information & communication | 2016 |
| Unity Shared Services Ltd | Administrative & support | 2021 |
| Unity Shares Ltd | Financial services | 2023 |
| Unity Tech Force Ltd | Information & communication | 2018 |
| Unity World Ltd | Wholesale & retail | 2016 |
| Universal Prime Traders Ltd | Wholesale & retail | 2024 |
| Universal Windows (NE) Limited | Construction | 2018 |
| University Centre Middlesbrough Limited | Education | 2011 |
| Unizone Consulting Limited | Hospitality | 2010 |
| Unleashed Events Ltd | Administrative & support | 2023 |
| Unwind ME Limited | Wholesale & retail | 2008 |
| UP the Music Services Ltd | Information & communication | 2024 |
| UP UP & Away Events Decor Ltd | Hospitality | 2021 |
| Updata Group Ltd | Information & communication | 2024 |
| Upex Electrical Distributors (Yorkshire) Limited | Wholesale & retail | 1997 |
| Upex Pies Limited | Manufacturing | 2015 |
| Upflo.Ws Ltd | Information & communication | 2026 |
| Upgrade Training Limited | Professional & scientific | 2000 |
| Uppal Convenience Stores (North East) Ltd | Wholesale & retail | 2024 |
| Upsall Hall Management Company Limited | Households | 2017 |
| Upsall Manor Management Company Limited | Households | 2017 |
| Upscale Management Services Ltd | Real estate | 2023 |
| Urban Quaters Ltd | Real estate | 2019 |
| Urban TAN Limited | Other services | 2018 |
| Urbanedge Resource Group Ltd | Administrative & support | 2025 |
| Urbanlink Projects Limited | Construction | 2020 |
| Urra Car Parks Limited | Real estate | 2021 |
| Urra Consultancy Limited | Professional & scientific | 2015 |
| Urra Holdings Limited | Financial services | 2021 |
| Urra Properties Limited | Real estate | 2014 |
| Urwins Electrical Services Limited | Construction | 2016 |
| US. UK. Trade Ltd | Wholesale & retail | 2025 |
| Used ME Cctv Solutions Ltd | Construction | 2025 |
| Usehirable Ltd | Information & communication | 2025 |
| Users R Important Limited | Professional & scientific | 2026 |
| Usher Comms Limited | Information & communication | 2014 |
| Ushna Zareen Ltd | Health & social care | 2022 |
| UTB Consultancy Services Limited | Professional & scientific | 2018 |