| Trivsel. UK Limited | Construction | 1991 |
| TRN (Train) Ltd. | Education | 2001 |
| Trojan Skips Ltd | Water & waste | 2015 |
| Trory Medical Services Limited | Health & social care | 2014 |
| TRT Rail Ltd | Construction | 2025 |
| TRU Pack Ltd | Manufacturing | 2026 |
| Tructyre Fleet Management Limited | Wholesale & retail | 2000 |
| Trudy MAY Limited | Professional & scientific | 2024 |
| True North Adventure Club Ltd | Arts & recreation | 2026 |
| True North Plumbing Ltd | Construction | 2026 |
| True North Strategic Support Ltd | Professional & scientific | 2025 |
| True North Supplies Ltd | Wholesale & retail | 2024 |
| True Temp Solutions Ltd | Construction | 2025 |
| Trumeau Limited | Real estate | 2007 |
| Trustline Heating and Plumbing Ltd | Construction | 2024 |
| Trustmark North East Ltd | Construction | 2024 |
| Trustmark Roofing and Building Limited | Construction | 2017 |
| Trwan & Co. Ltd | Health & social care | 2024 |
| TS Electrical NE Ltd | Construction | 2024 |
| TS Pharma Ltd | Health & social care | 2022 |
| TSI Freehold Property Ltd | Extraterritorial | 2015 |
| TSI Investors Ltd | Extraterritorial | 2015 |
| TSI Partnerships Ltd | Extraterritorial | 2015 |
| TSN Estates Ltd | Extraterritorial | 2008 |
| TSP Fulfilment Ltd | Transport & logistics | 2002 |
| TSP Realisations Limited | Manufacturing | 2019 |
| TT Evolutions Ltd | Wholesale & retail | 2025 |
| TT Inspections (TTI) Limited | Construction | 2025 |
| TT Newcastle Limited | Hospitality | 2019 |
| TT Program Ltd | Education | 2022 |
| TT UK Services Limited | Administrative & support | 2023 |
| Ttnz Limited | Health & social care | 2023 |
| Tuffluckrugz Ltd | Manufacturing | 2024 |
| Tufft Ltd | Administrative & support | 2026 |
| Tughyan Ltd | Real estate | 2025 |
| TUP Golf Ltd | Wholesale & retail | 2025 |
| Turbine Rework Limited | Manufacturing | 2019 |
| Turbo Pacs (Newcastle) Ltd | Wholesale & retail | 2018 |
| Turbo Power Systems Group Limited | Manufacturing | 2016 |
| Turbo Power Systems Limited | Manufacturing | 1992 |
| Turkish Trim Ltd | Other services | 2024 |
| Turner's of LOW Fell Ltd | Hospitality | 2019 |
| Turners Funfairs Limited | Administrative & support | 2025 |
| Turntide Drives Limited | Other services | 2021 |
| Turntide Transport Limited | Financial services | 2021 |
| Turtle Storage Limited | Transport & logistics | 2015 |
| Tuscany Food Company Limited | Extraterritorial | 1975 |
| TV Catering Ltd | Hospitality | 2016 |
| Tvmt Motorcycle Training Ltd | Education | 2024 |
| TVS 25 Ltd | Other services | 2025 |
| TW Luxury Living Ltd | Hospitality | 2024 |
| TW Plastering (NE) Limited | Construction | 2025 |
| TW Siah Investments Ltd | Real estate | 2020 |
| TWC Retail Limited | Wholesale & retail | 2024 |
| Twenty Properties Limited | Real estate | 2020 |
| Twenty SIX 03 Entertainment Limited | Information & communication | 2017 |
| TWENTY2SEVEN Ltd | Real estate | 2011 |
| Twentyseven Design Limited | Administrative & support | 2007 |
| Twentysix 03 Content Limited | Information & communication | 2015 |
| Twice Brewed Brew House LLP | | 2016 |
| Twice Brewed Brewing Company Ltd | Manufacturing | 2022 |
| Twin Tiling (Gateshead) Limited | Construction | 2017 |
| Twin Tiling (UK) Limited | Construction | 2017 |
| Twin Torque Ltd | Other services | 2023 |
| Two Coates Ltd | Construction | 2026 |
| Tycelt Properties Limited | Real estate | 1957 |
| Tyne & Tumble Laundry Ltd | Other services | 2026 |
| Tyne & Wear Care Services Ltd | Health & social care | 2023 |
| Tyne & Wear Insulation Ltd | Construction | 2024 |
| Tyne & Wear Lets Ltd | Households | 2022 |
| Tyne and Wear Autos Ltd | Wholesale & retail | 2023 |
| Tyne and Wear EPC Ltd | Administrative & support | 2020 |
| Tyne Heritage Estates Limited | Real estate | 2022 |
| Tyne Sheds Ltd | Manufacturing | 2025 |
| Tyne Social Community CIC | Other services | 2020 |
| Tyne Technical Services Ltd | Manufacturing | 2011 |
| Tyne Tees Ceramics Limited | Wholesale & retail | 1983 |
| Tyne Tees Electrical Contracting Limited | Construction | 1999 |
| Tyne Tees Finance Limited | Wholesale & retail | 1963 |
| Tyne Tees Recovery Ltd | Transport & logistics | 2025 |
| Tyne Valley Auctions Limited | Administrative & support | 2020 |
| Tyne Valley Health and Wellbeing Community Interest Company | Health & social care | 2020 |
| Tyneside Investments Limited | Real estate | 2012 |
| Tyneside Autohaus Limited | Manufacturing | 2016 |
| Tyneside Building & Maintenance Ltd | Construction | 2015 |
| Tyneside Carpet Cleaning Limited | Professional & scientific | 2023 |
| Tyneside Carpets Limited | Wholesale & retail | 2013 |
| Tyneside Commercial Management Ltd | Real estate | 2026 |
| Tyneside Home Improvements Limited | Construction | 2022 |
| Tyneside Metal and Waste Limited | Water & waste | 2017 |
| Tyneside Project Solutions Ltd | Administrative & support | 2012 |
| Tyneside Property Group Ltd | Real estate | 2018 |
| Tyneside Property Investments Ltd | Real estate | 2018 |
| Tyneside Residential Ltd | Households | 2024 |
| Tyneside Roofing Supplies Ltd | Wholesale & retail | 2025 |
| Tyneside Scaffolding Limited | Administrative & support | 2017 |
| Tyneside Skip Hire Limited | Water & waste | 2021 |
| Tyneside Surgical Services Limited | Health & social care | 2007 |
| Tyneside Women's Health | Education | 2008 |
| Tynestack Ltd | Professional & scientific | 2026 |