| Thinford Shavings J. W. Thompson Bulk Limited | Wholesale & retail | 2007 |
| Think Kudos Limited | Financial services | 2024 |
| Third Pole International Limited | Wholesale & retail | 2025 |
| Third Stone Properties Limited | Financial services | 2020 |
| Thirkell Logistics Ltd | Transport & logistics | 2026 |
| Thompson's Garden Antiques Ltd | Wholesale & retail | 2019 |
| Thomson West Limited | Real estate | 1974 |
| Thomson Wood Fuel Ltd | Wholesale & retail | 2023 |
| Thornex Options Limited | Real estate | 2021 |
| Thornrud Ltd | Hospitality | 2024 |
| Thorntons Developments Limited | Construction | 2015 |
| Thoroughgood Advisors Ltd | Financial services | 2021 |
| Those WHO Wander Ltd | Wholesale & retail | 2025 |
| Thpsychology Ltd | Real estate | 2023 |
| Threads of Hope, Sewing for a Brighter Future CIC | Manufacturing | 2025 |
| Three Bean Ltd | Hospitality | 2025 |
| Three Rivers Outdoor Club | Other services | 2009 |
| Thrive Investigations Ltd | Administrative & support | 2021 |
| Thrive Occupational Therapy Ltd | Health & social care | 2022 |
| Thrive Through Sport CIC | Education | 2026 |
| Thubron's School of Driving Ltd | Education | 2024 |
| Tiega Insulation Northern Ltd | Construction | 2024 |
| Tiger Creative Limited | Information & communication | 2015 |
| Till Roll World UK Ltd | Wholesale & retail | 2023 |
| TIM Jenkins Golf Limited | Wholesale & retail | 2003 |
| Timbercraft Windows Ltd | Manufacturing | 2024 |
| Timbermate (UK) Limited | Manufacturing | 2012 |
| TIME4ACTION Pathway CIC | Health & social care | 2025 |
| Timec 1334 Limited | Construction | 2011 |
| Timmins Tree Surgery Ltd | Administrative & support | 2023 |
| TIN of Sardines Poole Quay Limited | Hospitality | 2018 |
| Tipll Limited | Administrative & support | 2017 |
| Tiptop Distribution Ltd | Wholesale & retail | 2025 |
| TIR Dynamics Ltd | Information & communication | 2026 |
| Titan Solutions Limited | Information & communication | 2019 |
| Titash Indian Limited | Hospitality | 2025 |
| TJH Groundworks Ltd | Construction | 2025 |
| TJS Delivery Services Limited | Transport & logistics | 2022 |
| TK Convenient Store Ltd | Wholesale & retail | 2025 |
| TK Designs (Yorkshire) Limited | Professional & scientific | 2023 |
| TKB Property Ltd | Real estate | 2025 |
| TL (Wynyard) Limited | Financial services | 2020 |
| TM Electrical NE Limited | Construction | 2025 |
| TNF Fleet Services Limited | Wholesale & retail | 2026 |
| TNF Group NE Limited | Financial services | 2026 |
| TNF Haulage NE Limited | Administrative & support | 2026 |
| Toast Estates Ltd | Real estate | 2024 |
| Toast Housekeeping Limited | Administrative & support | 2018 |
| Toast Interiors Ltd | Wholesale & retail | 2022 |
| Toast Maintenance Ltd | Real estate | 2021 |
| Toast Properties Limited | Hospitality | 2011 |
| Tognarelli Ltd | Real estate | 2025 |
| TOM Conway Motorcycles Limited | Wholesale & retail | 1999 |
| Tomasz Niedzielski Limited | Wholesale & retail | 2023 |
| Tomatrux International Limited | Transport & logistics | 2017 |
| Tonks Recycling Limited | Water & waste | 2012 |
| Toot Holdings Ltd | Manufacturing | 2024 |
| Tooti Music Limited | Information & communication | 2025 |
| Topland (UK) Limited | Financial services | 2020 |
| Topshelfgoods Ltd | Wholesale & retail | 2025 |
| Toro Durham Limited | Hospitality | 2026 |
| Toro Gussto Limited | Hospitality | 2026 |
| Toro Property Group Ltd | Construction | 2019 |
| Total Electrical Solutions Limited | Construction | 2008 |
| Total Graphic Supplies Limited | Manufacturing | 1986 |
| Total Moulding Solutions Limited | Manufacturing | 2020 |
| Total Order Pro C.I.C. | Other services | 2022 |
| Total Roofing & Solar Limited | Construction | 2025 |
| Total Solar Guard Limited | Construction | 2026 |
| Total Waste Management NE Ltd | Water & waste | 2025 |
| Tower Regeneration Leasing Limited | Administrative & support | 2011 |
| Tower Regeneration Limited | Mining & quarrying | 2009 |
| Towers Engineering Design Services Limited | Construction | 1988 |
| Towhne Group Limited | Hospitality | 2024 |
| Town & Country Stoves Ltd | Wholesale & retail | 2023 |
| TP Electrical Supplies & Fixings Limited | Wholesale & retail | 2011 |
| TPW Home Improvements Ltd | Construction | 2026 |
| Tracey Russell Design Limited | Manufacturing | 2010 |
| Track a Phone Limited | Information & communication | 2002 |
| Track Tuned Parts Limited | Wholesale & retail | 2025 |
| Trade Home Improvements (NE) Limited | Construction | 2018 |
| Trade Smash Ltd | Information & communication | 2024 |
| Trades Team NE (Newcastle) Limited | Construction | 2025 |
| Trades Team NE (Sunderland) Limited | Administrative & support | 2025 |
| Trades Team NE Ltd | Construction | 2025 |
| Training-Direct Limited | Administrative & support | 2025 |
| Traj Properties Ltd. | Real estate | 2018 |
| Trans-Choice Limited | Professional & scientific | 2001 |
| Transbooks Limited | Extraterritorial | 2014 |
| Transformation Education CIC | Education | 2023 |
| Transfreeze Northern Limited | Manufacturing | 2012 |
| Transit Electronics Limited | Construction | 2012 |
| Transitional HR Limited | Professional & scientific | 2016 |
| Transport Management and Compliance Solutions Limited | Transport & logistics | 2022 |
| Transported IT Ltd | Transport & logistics | 2025 |
| Treeline Properties Ltd | Real estate | 2023 |
| Treesign Ltd | Administrative & support | 2021 |
| Trench Line Limited | Energy | 2025 |
| Trendporter Ltd | Wholesale & retail | 2025 |
| Trendy Padel Ltd | Wholesale & retail | 2025 |