| Teesside Sports Coaching Ltd | Administrative & support | 2025 |
| Teesside Sports for ALL CIC | Other services | 2025 |
| Tekmar EBT Limited | Professional & scientific | 2012 |
| Tekmar Energy Limited | Manufacturing | 2007 |
| Tekmar Group PLC | Financial services | 2018 |
| Tekmar Holdings Limited | Professional & scientific | 2011 |
| Tekmar Limited | Professional & scientific | 2011 |
| Tekmar Polyurethanes Limited | Manufacturing | 2007 |
| Temp Hero Limited | Extraterritorial | 2021 |
| Tempest Research Limited | Financial services | 2005 |
| Tenetrix Ltd | Professional & scientific | 2026 |
| TFT Aycliffe Ltd | Arts & recreation | 2026 |
| TH NDT Ltd | Professional & scientific | 2024 |
| THE Ascension Room Ltd | Professional & scientific | 2024 |
| THE B.B. Group Limited | Wholesale & retail | 1993 |
| THE Baby Milestone Company Limited | Manufacturing | 2024 |
| THE Bay Horse (Middridge) Limited | Hospitality | 2005 |
| THE Clinic (Catterick) Ltd | Other services | 2023 |
| THE County Restaurant Limited | Hospitality | 2011 |
| THE Darts Lounge Ltd | Wholesale & retail | 2024 |
| THE Detailing Guild Ltd | Wholesale & retail | 2025 |
| THE Durham UTC Limited | Education | 2013 |
| THE Embalming Academy Limited | Education | 2010 |
| THE Fellowship of Beer Ltd | Wholesale & retail | 2021 |
| THE Gambling Times Limited | Arts & recreation | 2016 |
| THE Garage DL5 Ltd | Wholesale & retail | 2026 |
| THE Gifted OWL Company Limited | Wholesale & retail | 2021 |
| THE Global Media Agency Ltd | Information & communication | 2016 |
| THE Good Ship Ltd | Information & communication | 2020 |
| THE Greenhouse Company (Groundwork) Limited | Other services | 2005 |
| THE Happy Baby Company Ltd | Education | 2021 |
| THE Happy Swim Company LLP | | 2019 |
| THE HUT (Proudfoot Drive) Limited | Hospitality | 2014 |
| THE Iron Emporium Ltd | Manufacturing | 2024 |
| THE Iron Horse Hotel Limited | Hospitality | 2017 |
| THE KEG Warehouse Ltd | Wholesale & retail | 2025 |
| THE Livefood Hub Ltd | Agriculture & fishing | 2020 |
| THE Milkman (Newton Aycliffe) Limited | Wholesale & retail | 2023 |
| THE Milkman Limited | Wholesale & retail | 2023 |
| THE Navy Club (Darlington) Limited | Hospitality | 2013 |
| THE Olive Garden (Durham) Ltd | Hospitality | 2017 |
| THE Pickled Parson Sedgefield Ltd | Hospitality | 2021 |
| THE Protection Parent Ltd | Professional & scientific | 2019 |
| THE Redeemed Christian Church of GOD, Mount Zion Centre Limited | Other services | 2023 |
| THE Robinson’S Industrial Roofing & Cladding Specialists Ltd | Construction | 2026 |
| THE Scouts Social Club Community Interest Company | Arts & recreation | 2018 |
| THE SEX Shop Limited | Extraterritorial | 1997 |
| THE Skin Health LAB & Training Academy Ltd | Other services | 2025 |
| THE Transporter '18 Ltd | Transport & logistics | 2018 |
| THE UK Neurodiversity Recognition Scheme Ltd | Education | 2025 |
| THE Veterans Community and Enterprise Centre ( Newton Aycliffe) CIC | Health & social care | 2024 |
| THE Vocational Learning Trust | Education | 2005 |
| THE Weirddough Pizza Company Ltd | Hospitality | 2024 |
| THE Wise Solutions Group Ltd | Construction | 2026 |
| THE Wooden Cracker Company Limited | Manufacturing | 2022 |
| THE Work Place (Aycliffe) Limited | Real estate | 2007 |
| Thefastestbeauty Limited | Wholesale & retail | 2022 |
| Thjp Ltd | Hospitality | 2024 |
| Thompson Race Engineering Ltd | Professional & scientific | 2017 |
| Thorpe Paddocks Residents Management Company Limited | Real estate | 2021 |
| Tidal Services Limited | Information & communication | 2020 |
| Tiger R.P. Holdings Ltd | Financial services | 2026 |
| Timfranco Limited | Professional & scientific | 2016 |
| Titan Property Services (NE) Ltd | Construction | 2018 |
| Todd Marketing Limited | Professional & scientific | 2026 |
| Tomax Engineering Ltd | Professional & scientific | 2024 |
| Total Cards Ltd | Wholesale & retail | 2018 |
| Total Connect Group Ltd | Information & communication | 2020 |
| Tracnet Limited | Information & communication | 2024 |
| Trailer Projects Ltd | Manufacturing | 2021 |
| Tranceport Ltd | Transport & logistics | 2024 |
| Travers Auto Services Ltd | Wholesale & retail | 2018 |
| Tree-Tops Occupational Therapy Holdings Limited | Financial services | 2026 |
| Tree-Tops Occupational Therapy Limited | Health & social care | 2001 |
| Tribe Facilities Management Ltd | Professional & scientific | 2023 |
| Trickybet Limited | Arts & recreation | 2016 |
| Tricogen Laboratories Limited | Manufacturing | 1949 |
| Trimdon Fisheries Ltd | Hospitality | 2025 |
| Triple-R (NE) Limited | Financial services | 2021 |
| True Vulture Ltd | Information & communication | 2023 |
| TSG NE Ltd | Construction | 2023 |
| Turner Quality Solutions Ltd | Professional & scientific | 2024 |
| Turnkey Building Services Ltd | Construction | 2019 |
| TW Network Solutions Limited | Construction | 2017 |
| Twin Interiors Ltd | Wholesale & retail | 2014 |
| Tyne Medical Clinic Ltd | Health & social care | 2025 |
| U.K. Marble Limited | Manufacturing | 1994 |
| Uber Shield Products Ltd | Manufacturing | 2018 |
| Ubunto Properties Limited | Real estate | 2025 |
| Ubuntu Properties Limited | Real estate | 2025 |
| Uhrda Education INT. Ltd | Education | 2017 |
| Unique Community Health & Fitness CIC | Arts & recreation | 2025 |
| Unity Groundworks Ltd | Construction | 2020 |
| Upex Electrical Distributors Limited | Wholesale & retail | 1987 |
| Urban Surface Protection Limited | Construction | 2006 |
| Urban Vision Properties Ltd | Real estate | 2025 |
| Utilities Services & Civils Ltd | Construction | 2021 |
| Utopia Plumbing Solutions Limited | Construction | 2022 |
| Vali Hustle Ltd | Wholesale & retail | 2025 |
| Vantage Group NE Ltd | Construction | 2017 |