| THE Court (Durham) Limited | Hospitality | 2026 |
| THE Craft Cabin North East C.I.C. | Arts & recreation | 2019 |
| THE Cusp Collective Ltd | Education | 2025 |
| THE Dog Boutique Limited | Other services | 2021 |
| THE Durham Leatherworker Ltd | Manufacturing | 2021 |
| THE Farmhouse Kitchen Leamside Limited | Hospitality | 2020 |
| THE Grill (NE) Limited | Hospitality | 2023 |
| THE Grove Pre-School | Education | 2007 |
| THE Little Olive Tree NE Ltd | Hospitality | 2025 |
| THE Newfield Sarnie Shop Ltd | Hospitality | 2021 |
| THE North Fairy Ltd | Administrative & support | 2025 |
| THE Northumberland GIN Company Limited | Manufacturing | 2017 |
| THE Novelty Gift Box People Ltd | Wholesale & retail | 2022 |
| THE Nutrition Nurse Ltd | Health & social care | 2023 |
| THE Oak Gateshead Ltd | Hospitality | 2024 |
| THE Old Bath House Land Limited | Real estate | 2018 |
| THE Old Chippy Limited | Hospitality | 2014 |
| THE Old Methodist Chapel Private Sessions Ltd | Information & communication | 2026 |
| THE Old Stables Financial Services Ltd | Financial services | 2006 |
| THE Other Brother Limited | Arts & recreation | 2019 |
| THE Projects House Limited | Information & communication | 2023 |
| THE Rising Sun Locomotive Trust Limited | Manufacturing | 2012 |
| THE Social Media Angels Limited | Administrative & support | 2011 |
| THE Tarot Therapist Ltd | Health & social care | 2024 |
| THE Training and Skills Academy CIC | Education | 2023 |
| THE UK Development Group Limited | Other services | 2015 |
| THE VIP Lounge @ Marina Ltd | Hospitality | 2026 |
| THE Wedding Wardrobe Ltd | Wholesale & retail | 2015 |
| THE Whitehouse Experience Limited | Professional & scientific | 2005 |
| Theblackbirdgallery Ltd | Wholesale & retail | 2025 |
| Thenji&Dumo Ltd | Health & social care | 2025 |
| Thermovita UK Ltd | Wholesale & retail | 2025 |
| Thompson Brothers Building & Roofing Ltd | Construction | 2020 |
| Thorniehall Farm Limited | Real estate | 2017 |
| Thornwood and Wellbrook Limited | Hospitality | 2023 |
| Thread Couture Ltd | Wholesale & retail | 2025 |
| Tichys Ltd | Wholesale & retail | 2025 |
| Tiffen Estates Limited | Real estate | 2021 |
| Tiffen Group Ltd | Other services | 2018 |
| Till Tech Limited | Manufacturing | 2015 |
| TIM Stonock Limited | Professional & scientific | 2017 |
| Timeless Entertainment Group Limited | Arts & recreation | 2021 |
| Tinkler Tsco Ltd | Extraterritorial | 2017 |
| Tiny Tinkers Ltd | Health & social care | 2022 |
| TJ Software Consultancy Limited | Information & communication | 2021 |
| TJX Holdings Limited | Financial services | 2026 |
| TM Rentals Ltd | Real estate | 2021 |
| TML Dental Prosthetics Limited | Manufacturing | 2018 |
| TMR Services Ltd | Wholesale & retail | 2025 |
| Tomahawk Outdoor Clothing Ltd | Wholesale & retail | 2022 |
| Tombola House Limited | Extraterritorial | 1961 |
| Tony Bainbridge GAS Services Ltd | Professional & scientific | 2013 |
| Top Nails Bar Ltd | Other services | 2022 |
| Total Home Solutions (NE) Limited | Construction | 2009 |
| Touch-Learn International Limited | Education | 2009 |
| Townjp Ltd | Hospitality | 2025 |
| TPM Electrical Ltd | Construction | 2026 |
| Tracey Wilson Limited | Education | 2014 |
| Trade OFF Grid Limited | Administrative & support | 2025 |
| Tradeflow Solutions Ltd | Administrative & support | 2026 |
| Transport & Warehouse Solutions (NE) Ltd | Transport & logistics | 2019 |
| Trawler Fresh Limited | Wholesale & retail | 2015 |
| Trilift UK Limited | Other services | 2017 |
| Trimdon PO Ltd | Wholesale & retail | 2025 |
| Trinity Business Group Ltd | Professional & scientific | 2026 |
| True Love Tattoo Ltd | Wholesale & retail | 2017 |
| True North Tribe Ltd | Other services | 2024 |
| Truepast Limited | Administrative & support | 2011 |
| Truetone Productions Limited | Arts & recreation | 2020 |
| TSH Homes Limited | Real estate | 2018 |
| TTP Genre Films Limited | Information & communication | 2022 |
| Tulip SA Holdings Limited | Financial services | 2023 |
| Tulipalo Exceptional Fires Ltd | Construction | 2019 |
| Tulipalo LLP | | 2013 |
| Turner & Budd Cleaning Services Limited | Administrative & support | 2003 |
| Turner's Army Surplus Limited | Wholesale & retail | 2025 |
| Turner's Kitchen Ltd | Hospitality | 2025 |
| Turtle Brothers Ltd | Real estate | 2021 |
| Turtle Enviro Limited | Manufacturing | 2016 |
| TV ROM Limited | Information & communication | 2019 |
| TW Property Holdings Limited | Real estate | 2020 |
| TWD Heating Services Ltd | Construction | 2020 |
| Two Sweet Peas Limited | Hospitality | 2018 |
| Tyne Gadget Ltd | Wholesale & retail | 2024 |
| Tyne Tees Pest & Bird Control Limited | Other services | 2024 |
| Tyne Valley Express Limited | Information & communication | 2014 |
| Tyneside Building and Joinery Ltd | Construction | 2017 |
| Tyol Limited | Energy | 2024 |
| Tyoltd Limited | Professional & scientific | 2022 |
| Tyre Spot Limited | Wholesale & retail | 1993 |
| Tyres North Limited | Extraterritorial | 1997 |
| U K a S F P | Other services | 2011 |
| U.K Truckmixer Training Limited | Education | 2018 |
| Ubique Property Solutions Ltd | Construction | 2024 |
| UK Horticulture Ltd | Wholesale & retail | 2024 |
| UK Refrigeration and Shopfitting Ltd | Other services | 2025 |
| UK Sustainable Energy Limited | Manufacturing | 2008 |
| Ukeg Belper Administration Limited | Administrative & support | 2016 |
| Ukpoptops Limited | Manufacturing | 2012 |
| Ularoojp Ltd | Hospitality | 2025 |