| TA Training & Consultancy Ltd | Administrative & support | 2019 |
| Taaz Designs Limited | Wholesale & retail | 2025 |
| Tactical Instrumentation and Training Solutions UK Ltd | Administrative & support | 2022 |
| TAG International Group Limited | Manufacturing | 2026 |
| Tailors 4 Interiors Ltd | Manufacturing | 2023 |
| Taiz Energy Ltd | Professional & scientific | 2024 |
| TAL Project Services Ltd | Professional & scientific | 2026 |
| Talentiiq Bridge Limited | Professional & scientific | 2026 |
| Talentlinq Consortium Ltd. | Administrative & support | 2023 |
| Tales of Toria Ltd | Wholesale & retail | 2020 |
| Talintyre Ergonomics Ltd | Other services | 2024 |
| Talk Time Middlesbrough Ltd | Other services | 2022 |
| Talk Time Repair Ltd | Other services | 2026 |
| Talktime Mobiles Ltd | Wholesale & retail | 2011 |
| Tamanda Limited | Manufacturing | 2019 |
| Tame Bridge Cars Ltd | Wholesale & retail | 2019 |
| Tame Bridge Residents Limited | Professional & scientific | 2007 |
| Tamseela Iqbal Ltd | Administrative & support | 2024 |
| Tamur R/A Construction Services Ltd | Construction | 2025 |
| TAN Station Stokesley Limited | Other services | 2025 |
| Tana Tigre Ltd | Real estate | 2024 |
| Tanned & Fabulous Limited | Other services | 2026 |
| TAP 'N Business & Network Ltd | Wholesale & retail | 2026 |
| TAP Auto LAB Ltd | Wholesale & retail | 2026 |
| Tarcon Limited | Construction | 2013 |
| Target NE Ltd | Wholesale & retail | 2020 |
| Tarren Build Limited | Construction | 2024 |
| Taste of Smash Burger Ltd | Hospitality | 2025 |
| Taste of Thyme Ltd | Hospitality | 2025 |
| Tasteflare Ltd | Wholesale & retail | 2025 |
| Tasties M Ltd | Hospitality | 2026 |
| Tastradingseller Ltd | Wholesale & retail | 2026 |
| Tasty Tarts Ltd | Manufacturing | 2020 |
| Tastynest Ltd | Hospitality | 2022 |
| Tatraining&Siteservices Ltd | Construction | 2025 |
| Tayca (Thailand) Co. Ltd. | Wholesale & retail | 2025 |
| Taylor Goodchild Limited | Professional & scientific | 2011 |
| Taylor Harris Associates Ltd | Households | 2019 |
| Taylor Watmore Limited | Wholesale & retail | 2021 |
| Taylormades Security Ltd | Public administration | 2025 |
| TB Lifting Ltd | Construction | 2024 |
| TC HV Services Limited | Construction | 2024 |
| TCC Contracting Limited | Construction | 2024 |
| TCC Energy Ltd | Energy | 2024 |
| TCC Land Limited | Real estate | 2023 |
| TCC Metals Ltd | Water & waste | 2023 |
| TCC Plant Ltd | Water & waste | 2020 |
| Tcestético Ltd | Health & social care | 2022 |
| TCF Construction Limited | Professional & scientific | 2023 |
| TCH 31 Limited | Other services | 2013 |
| TDD Ventures Ltd | Wholesale & retail | 2026 |
| Tdpec Ltd | Education | 2023 |
| Teacher Time Limited | Education | 2014 |
| Team L Ltd | Construction | 2023 |
| Tech Curve Solutions Ltd | Information & communication | 2025 |
| Tech FIX Ltd | Manufacturing | 2021 |
| Tech Founders Group Ltd | Information & communication | 2024 |
| Tech Markups Ltd | Wholesale & retail | 2023 |
| TECH4THETRADE Ltd | Information & communication | 2025 |
| TECHFINITY4U Limited | Manufacturing | 2019 |
| Technical Documentation World Ltd | Information & communication | 2010 |
| Technoloid Limited | Information & communication | 2024 |
| Techpink Limited | Professional & scientific | 2013 |
| Techquity Limited | Information & communication | 2017 |
| Techstaff Limited | Administrative & support | 2025 |
| Techstone Solutions Ltd | Information & communication | 2025 |
| Techtra Solutions Ltd | Wholesale & retail | 2025 |
| Techworx Skillbase Limited | Health & social care | 2013 |
| Tecnicas Agile Solutions Ltd | Professional & scientific | 2020 |
| TED & Luna Ltd | Construction | 2025 |
| TED Alert UK Ltd | Administrative & support | 2018 |
| Ted's Housing Agency Ltd | Real estate | 2024 |
| Teeceey-Tech Ltd | Information & communication | 2026 |
| Tees Academy Ltd | Arts & recreation | 2021 |
| Tees Builders Ltd | Construction | 2022 |
| Tees Business Limited | Extraterritorial | 2017 |
| Tees Completions Ltd | Professional & scientific | 2025 |
| Tees Engineering Services Limited | Professional & scientific | 2018 |
| Tees Equine Ltd | Agriculture & fishing | 2024 |
| Tees Fire & Security Ltd | Construction | 2020 |
| Tees Fire Systems Limited | Construction | 2002 |
| Tees Forge Limited | Construction | 2026 |
| Tees Functional Fitness Ltd | Arts & recreation | 2019 |
| Tees Inspection Ltd | Construction | 2021 |
| Tees Maritime Cluster Limited | Administrative & support | 2024 |
| Tees Medical Services Ltd | Health & social care | 2016 |
| Tees MOT Services Limited | Wholesale & retail | 2009 |
| Tees Pest Quest Ltd | Administrative & support | 2022 |
| Tees Precision Engineering Ltd | Professional & scientific | 2026 |
| Tees Property Group Limited | Construction | 2026 |
| Tees Property Services Ltd | Construction | 2020 |
| Tees Rail & Civils Ltd | Construction | 2022 |
| Tees S.U. Limited | Administrative & support | 2010 |
| Tees Security Limited | Administrative & support | 2013 |
| Tees Sport Limited | Professional & scientific | 1976 |
| Tees Testing Limited | Construction | 1994 |
| Tees Transit Limited | Professional & scientific | 2003 |
| Tees Valley Consultants Ltd | Professional & scientific | 2020 |
| Tees Valley Contractors Limited | Water & waste | 2026 |
| Tees Valley Education | Education | 2015 |