| Thespaclinic Ltd | Administrative & support | 2017 |
| Theuniqueemporium Ltd | Wholesale & retail | 2023 |
| Thewles Shavings Ltd | Wholesale & retail | 2022 |
| Think GTI Ltd | Information & communication | 2010 |
| Thinkcog Ltd | Information & communication | 2025 |
| Thirsty Souls Ltd | Hospitality | 2025 |
| Thiyash & Reyaan Ltd | Real estate | 2025 |
| Thomas : Stevenson LLP | | 2016 |
| Thomas Burton Ltd | Manufacturing | 2022 |
| Thomas Hurst Consultancy Limited | Professional & scientific | 2019 |
| Thomas James Accountancy Ltd | Professional & scientific | 2024 |
| Thompson Estates NE Limited | Construction | 2025 |
| Thompson Estates North Limited | Construction | 2025 |
| Thompson Rentals Limited | Administrative & support | 2012 |
| Thompson Rentals North East Ltd | Administrative & support | 2020 |
| Thorna Ltd | Hospitality | 2025 |
| Thornaby and Ingleby Barwick Football Club Limited | Arts & recreation | 2014 |
| Thornaby Food Ltd | Hospitality | 2025 |
| Thornaby Istanbul Barber Ltd | Other services | 2024 |
| Thornaby Landscapes Limited | Administrative & support | 2019 |
| Thornaby Letting Ltd | Real estate | 2024 |
| Thornaby Ltd | Professional & scientific | 2025 |
| Thornaby Pavilion Badminton Club Ltd | Arts & recreation | 2022 |
| Thornaby R & T Ltd | Real estate | 2022 |
| Thornaby Retail Limited | Real estate | 2013 |
| Thornaby Snooker Centre Limited | Hospitality | 1999 |
| Thornaby Spitfire Ltd | Wholesale & retail | 2025 |
| Thornaby Windtec Ltd | Construction | 2017 |
| Thorntree Farm Limited | Manufacturing | 2012 |
| Thoroughbred Homes Limited | Construction | 1996 |
| Thorpe House Norton Management Company Limited | Households | 2001 |
| Thorpe Thewles Management Services Limited | Real estate | 2008 |
| Threadpoint Capital Partners Ltd | Professional & scientific | 2025 |
| Three Rivers Ingleby Barwick Limited | Hospitality | 2016 |
| Throughfilm CIC | Information & communication | 2022 |
| Thurston Accommodation Ltd | Real estate | 2025 |
| THW Ltd | Professional & scientific | 2023 |
| Thyme Square Ltd | Hospitality | 2024 |
| Tiedentity Limited | Wholesale & retail | 2024 |
| Tigerlily Healthcare Limited | Health & social care | 2019 |
| Tight 5 Apparel Ltd | Wholesale & retail | 2023 |
| Tikko Secure by Design Ltd | Information & communication | 2025 |
| TIL Death Club Limited | Wholesale & retail | 2024 |
| Tillybell Limited | Manufacturing | 2026 |
| TIM Gale Limited | Information & communication | 2023 |
| Timber Direct Teeside Limited | Manufacturing | 2025 |
| Time Goes by Limited | Wholesale & retail | 2023 |
| Time Piece Traders Ltd | Information & communication | 2023 |
| Time to ACT PLC | Professional & scientific | 2011 |
| Timeless Socials Ltd | Professional & scientific | 2024 |
| Tioxide Limited | Extraterritorial | 2026 |
| Tioxide Materials Ltd | Manufacturing | 2025 |
| Tipper Holdings Limited | Real estate | 2019 |
| TIS Consulting Ltd | Professional & scientific | 2020 |
| Tisa Limited | Extraterritorial | 2015 |
| Tisa Living Ltd | Wholesale & retail | 2026 |
| Titan Fabrications Ltd | Manufacturing | 2018 |
| Titan Facades Ltd | Construction | 2019 |
| Titanium Renewable Services Ltd | Construction | 2019 |
| Tixall Consulting Limited | Professional & scientific | 2025 |
| TJ Engineering Services(North East) Ltd | Professional & scientific | 2022 |
| Tj's Express Shack Ltd | Hospitality | 2024 |
| TJH Rigging Services Ltd | Construction | 2026 |
| TJS GAS & Heating Ltd | Construction | 2024 |
| TKB Rigging&Lifting Ltd | Construction | 2026 |
| TKS Productions Ltd | Arts & recreation | 2023 |
| TKS Trading Limited | Wholesale & retail | 2017 |
| TKT Care Limited | Health & social care | 2020 |
| TLC Diamonds Limited | Manufacturing | 2022 |
| TMS Business Coaching Limited | Public administration | 2025 |
| TOM Cheffy Ltd | Administrative & support | 2025 |
| TOM Dixon Enterprises Ltd | Construction | 2017 |
| Tomahawk Steakhouse Harrogate Limited | Hospitality | 2014 |
| Tomahood Limited | Real estate | 2019 |
| Tommyt's Foods Ltd | Hospitality | 2021 |
| Tommyts Ltd | Wholesale & retail | 2026 |
| Tomorrows Leaders (North East) CIC | Education | 2014 |
| Tonmichelle Ltd | Hospitality | 2023 |
| Tootibooti Limited | Wholesale & retail | 2025 |
| Top Deck Solutions Limited | Professional & scientific | 2013 |
| Top JOB Deliveries Ltd | Transport & logistics | 2026 |
| Top Nails & Spa 88 Ltd | Other services | 2026 |
| Top Shelf Installations Ltd | Construction | 2007 |
| Top Teessiders Limited | Information & communication | 2023 |
| Top Tier Healthcare Limited | Health & social care | 2023 |
| Topaz Landseer Limited | Wholesale & retail | 2019 |
| Topspot Marketing Ltd | Professional & scientific | 2026 |
| Torvex Energy Limited | Professional & scientific | 2013 |
| Total Access Scaffolding (NE) Limited | Administrative & support | 2015 |
| Total Bleed Solutions Limited | Manufacturing | 2016 |
| Total Control & Distribution Limited | Manufacturing | 2006 |
| Total Padel Solutions Ltd | Wholesale & retail | 2025 |
| Total Resurfacing Ltd | Construction | 2024 |
| Total Sport Academy Ltd | Arts & recreation | 2007 |
| Totrain Ltd | Education | 2026 |
| Toulson Plumbing & Heating Limited | Construction | 2018 |
| Toulson Property Investors & Lettings Limited | Real estate | 2021 |
| Touran Parts North East Ltd | Wholesale & retail | 2024 |
| Tower Angel Ltd | Wholesale & retail | 2024 |
| Tower Court Management Company Limited | Real estate | 2017 |