| Tall Trees Assets Limited | Real estate | 2025 |
| Talvexa Ltd | Extraterritorial | 2023 |
| Tams Accountants and Business Advisors Limited | Professional & scientific | 2026 |
| Tanfield Brothers Limited | Construction | 2001 |
| TAP Property Holdings Ltd | Real estate | 2025 |
| Tapdigital Limited | Information & communication | 2003 |
| Taps Care Limited | Administrative & support | 2025 |
| Tara Projects Limited | Real estate | 2011 |
| Task-It Group Ltd | Administrative & support | 2019 |
| Taste Palace Limited | Hospitality | 2019 |
| Tasty Experience CP Limited | Hospitality | 2025 |
| Tastyz Ltd | Hospitality | 2023 |
| Taunton Hand Car Wash Ltd | Other services | 2019 |
| Tax Incentivised Savings Association | Other services | 2018 |
| Taxitees Ltd | Transport & logistics | 2026 |
| Taylor Cullen Limited | Administrative & support | 2014 |
| Taylor Foster Limited | Professional & scientific | 2011 |
| Taylor Made Marketing Associates Ltd | Professional & scientific | 2012 |
| Taylor SEN Consultancy Limited | Education | 2023 |
| Taylormade Solutions Ltd | Construction | 2012 |
| Taymac Properties Limited | Real estate | 2021 |
| Taymac Tanning Limited | Other services | 2025 |
| TB Engineering Consultants Limited | Professional & scientific | 2016 |
| TBC Solutions Ltd | Construction | 2022 |
| TC Caravan Holidays Ltd | Hospitality | 2022 |
| TCG Centre Limited | Wholesale & retail | 2021 |
| Tcorp Innovations Ltd | Information & communication | 2025 |
| TCS CAD & BIM Solutions Limited | Information & communication | 1997 |
| TCS Civils Ltd | Construction | 2022 |
| TD BFD Ltd | Hospitality | 2024 |
| Teach Luminous Limited | Education | 2018 |
| Team Thomson Consultancy Ltd | Professional & scientific | 2026 |
| Teawp Ltd | Professional & scientific | 2026 |
| Tech Traders Tees Ltd | Wholesale & retail | 2023 |
| Techiaz IT Ltd | Information & communication | 2017 |
| Teddy Bears Day Nursery (Thornaby) Ltd | Education | 2019 |
| Tees Bridge Holdings Ltd | Financial services | 2024 |
| Tees Bridge Properties Ltd | Real estate | 2022 |
| Tees CAB Ltd | Transport & logistics | 2023 |
| Tees Consultancy Services Limited | Professional & scientific | 2011 |
| Tees Digital Limited | Wholesale & retail | 2025 |
| Tees Haven Limited | Construction | 2025 |
| Tees Heritage Trust Limited | Construction | 1982 |
| Tees Inns Ltd | Hospitality | 2017 |
| Tees Inshore Marine Services Limited | Administrative & support | 2012 |
| Tees Lift OFF CIC | Education | 2026 |
| Tees Project Solutions Limited | Professional & scientific | 2023 |
| Tees Quantum Services Limited | Professional & scientific | 2024 |
| Tees Recovery Service Ltd | Water & waste | 2025 |
| Tees Resource Limited | Administrative & support | 2021 |
| Tees Solar Limited | Energy | 2026 |
| Tees Technical Services Ltd | Administrative & support | 2015 |
| Tees Timber Play Ltd | Manufacturing | 2026 |
| Tees Tree Surgery Ltd | Agriculture & fishing | 2025 |
| Tees T’S Ltd | Wholesale & retail | 2025 |
| Tees Valley Apartments Ltd | Hospitality | 2014 |
| Tees Valley Caravans Ltd | Wholesale & retail | 2020 |
| Tees Valley Chinese Community Centre Ltd | Arts & recreation | 2003 |
| Tees Valley Cladding Ltd | Construction | 2022 |
| Tees Valley Community Church | Other services | 2006 |
| Tees Valley Community Foundation | Professional & scientific | 2005 |
| Tees Valley Customer Care Limited | Construction | 2022 |
| Tees Valley Drinks Ltd | Wholesale & retail | 2023 |
| Tees Valley Energy Ltd | Other services | 2013 |
| Tees Valley Exteriors Limited | Construction | 2018 |
| Tees Valley Flooring Limited | Construction | 2022 |
| Tees Valley Joinery Limited | Professional & scientific | 2017 |
| Tees Valley Judo CIC | Arts & recreation | 2026 |
| Tees Valley Monitor Ltd | Information & communication | 2021 |
| Tees Valley Motors Ltd | Wholesale & retail | 2023 |
| Tees Valley Properties Limited | Real estate | 2018 |
| Tees Valley Property Solutions Ltd | Households | 2020 |
| Tees Valley Refurbishments Ltd | Construction | 2024 |
| Tees Valley Rentals Limited | Real estate | 2024 |
| Tees Valley Safety Ltd. | Professional & scientific | 2018 |
| Tees Valley Service Centre Ltd | Wholesale & retail | 2020 |
| Tees Valley Trade Group Limited | Construction | 2013 |
| Tees Valley Tradesmen Limited | Administrative & support | 2017 |
| Teesdance Ltd | Arts & recreation | 2021 |
| Teesfit Ltd | Wholesale & retail | 2023 |
| Teeside Grocers Ltd | Real estate | 2021 |
| Teeside Peri Peri Ltd | Hospitality | 2025 |
| Teeside Rental Ltd | Administrative & support | 2025 |
| Teeskleen Limited | Administrative & support | 2010 |
| Teespoint Construction Limited | Construction | 2016 |
| Teesside Accountants Limited | Extraterritorial | 2011 |
| Teesside Anthropologist Ltd | Professional & scientific | 2025 |
| Teesside Architectural Salvage Ltd | Water & waste | 2008 |
| Teesside Cars Ltd | Wholesale & retail | 2025 |
| Teesside Cleaners Ltd | Administrative & support | 2018 |
| Teesside Clinical Psychology Ltd | Professional & scientific | 2020 |
| Teesside Coatings and Access Limited | Construction | 2014 |
| Teesside Containers Limited | Transport & logistics | 2014 |
| Teesside Diagnostics Ltd | Health & social care | 2024 |
| Teesside Driveways & Property Maintenance Ltd | Construction | 2015 |
| Teesside Earwax Removal Ltd. | Health & social care | 2023 |
| Teesside Electrical & Fire Limited | Construction | 2020 |
| Teesside Eris Car Wash Ltd | Administrative & support | 2025 |
| Teesside Finance Limited | Financial services | 2014 |
| Teesside Gravity CIC | Education | 2026 |