| Trevor Cartner Services Limited | Real estate | 2020 |
| Trexioranda Ltd | Wholesale & retail | 2025 |
| Tribe Construction Ltd | Other services | 2017 |
| Triclarity Consulting Ltd | Information & communication | 2024 |
| Trident Tackle Development Ltd | Manufacturing | 2019 |
| Trinity AH1 Ltd | Construction | 2022 |
| Tripleduo U.K. Limited | Real estate | 2019 |
| Tripod Properties Durham Ltd | Real estate | 2019 |
| TROCI14 Limited | Hospitality | 2026 |
| Tropical Supplies North East Limited | Wholesale & retail | 2015 |
| Trow Consulting Limited | Administrative & support | 2003 |
| Tru-Green Limited | Administrative & support | 2011 |
| True Nest Properties Ltd | Real estate | 2024 |
| True Padel Holdco Ltd | Arts & recreation | 2024 |
| True Padel Ltd | Arts & recreation | 2022 |
| True Padel Sunderland Ltd | Arts & recreation | 2024 |
| True Padel Tyneside Central Ltd | Arts & recreation | 2024 |
| True Padel Tyneside Ltd | Arts & recreation | 2024 |
| True Padel West Ltd | Arts & recreation | 2026 |
| Trueelegance Ltd | Other services | 2024 |
| Truit Consulting Ltd | Information & communication | 2007 |
| Trusso Properties Ltd | Real estate | 2022 |
| Trusted Partner Networks Ltd | Professional & scientific | 2018 |
| TS Shumbs Limited | Financial services | 2016 |
| TSC Huang Limited | Hospitality | 2022 |
| TT Durham Ltd | Hospitality | 2025 |
| TTR Belmont Limited | Hospitality | 2022 |
| TU Consulting Ltd | Professional & scientific | 2022 |
| TUA GIS Specialists Limited | Information & communication | 2023 |
| Tucket Limited | Professional & scientific | 2009 |
| TUK TUK Durham Limited | Hospitality | 2019 |
| Tunstall Associates Ltd | Professional & scientific | 2008 |
| Tunstall Homes Limited | Real estate | 2013 |
| Turbil Ltd | Wholesale & retail | 2025 |
| Turbo Factors Ltd | Manufacturing | 2023 |
| Turbo Gains Capital Ltd | Professional & scientific | 2021 |
| Turkish Barber Durham Ltd | Other services | 2024 |
| Turnbull Groundworks Limited | Construction | 2025 |
| Turnbull Safety & Inspection Limited | Public administration | 2013 |
| Turner Trading Ltd | Wholesale & retail | 2024 |
| Tursdale Park Limited | Real estate | 2026 |
| Tursdale Recycling Limited | Professional & scientific | 2003 |
| Turtles Nursery Limited | Education | 2010 |
| Tutay Research Ltd | Professional & scientific | 2026 |
| Tvmc Limited | Professional & scientific | 2003 |
| TW Utilities Ltd | Construction | 2025 |
| Twelvth Limited | Information & communication | 2024 |
| Twenty Three Salon Ltd | Other services | 2022 |
| Two Lives (TLC3) Ltd | Professional & scientific | 2025 |
| TWS Automation Ltd | Manufacturing | 2023 |
| TWS Properties NE Ltd | Real estate | 2025 |
| Tyne & Wear Chamber of Commerce, Trade & Industry Limited | Professional & scientific | 1994 |
| Tyne and Wear Estates Ltd | Real estate | 2023 |
| Tyne Haulage Co Limited | Construction | 2025 |
| Tyne Haulage Co NE Ltd | Transport & logistics | 2026 |
| Tynedale Roadstone Limited | Manufacturing | 1999 |
| Tynedex Limited | Real estate | 2002 |
| Tynemouth Safety Services Limited | Professional & scientific | 2021 |
| Tyre Discounts and Auto Services Limited | Wholesale & retail | 1972 |
| Tyre Revolution Limited | Wholesale & retail | 2012 |
| Tyre Right Limited | Wholesale & retail | 2025 |
| Tz&Rs Group Ltd | Hospitality | 2025 |
| Udara Limited | Information & communication | 2017 |
| UK and Ireland Spill Association Limited | Other services | 2016 |
| UK Commerce Exchange Limited | Energy | 2019 |
| UK Food Events Ltd | Wholesale & retail | 2026 |
| UK Robin Ltd | Wholesale & retail | 2024 |
| Ukcoregroup Ltd | Manufacturing | 2025 |
| UKG Trading Limited | Wholesale & retail | 2011 |
| Uktm Limited | Construction | 2020 |
| Ukyc Academy Ltd | Professional & scientific | 2024 |
| Ultimate Bedrooms Ltd | Wholesale & retail | 2011 |
| Ultimate Property Maintenance Services Ltd | Construction | 2022 |
| Ulvan Ltd | Wholesale & retail | 2025 |
| Ulyatt Property Limited | Real estate | 2005 |
| UMI Commercial Limited | Professional & scientific | 2010 |
| UMI Employee Ownership Trustee Co Limited | Other services | 2010 |
| UMI Funding Services Limited | Financial services | 2024 |
| UMI Holdings Limited | Professional & scientific | 2009 |
| UMI Investment Limited | Financial services | 2018 |
| Unbenannt Ltd | Arts & recreation | 2018 |
| Unbox Limited | Hospitality | 2019 |
| Unbox Poplar Limited | Real estate | 2022 |
| Uniform Supplies Ltd | Wholesale & retail | 2022 |
| Union Northeast Limited | Construction | 2025 |
| Unipod Media Ltd | Information & communication | 2024 |
| Unique (NE) Limited | Arts & recreation | 2022 |
| Unique 4 ALL CIC | Administrative & support | 2025 |
| Unique Creative Hair and Beauty Ltd | Other services | 2018 |
| Unique Education and Training Limited | Administrative & support | 2020 |
| Unique Scapes UK Ltd | Administrative & support | 2024 |
| Uniquely Healthy Limited | Other services | 2012 |
| United Bullion Ltd | Professional & scientific | 2025 |
| United North East Ltd | Real estate | 2021 |
| Unitedkingdomdevelopments Ltd | Construction | 2025 |
| Unitoshine Ltd | Other services | 2020 |
| Unity Flooring Ltd | Construction | 2025 |
| Unjaded Aesthetics Ltd | Health & social care | 2025 |
| Unld Ltd | Wholesale & retail | 2025 |
| Until Dusk Ltd | Hospitality | 2025 |