| TLM Developments Limited | Real estate | 2002 |
| TLT Medical Services Limited | Health & social care | 2019 |
| TM & S Group Limited | Households | 2020 |
| TM Pubco Limited | Hospitality | 2025 |
| Tmbailey Solutions Ltd | Information & communication | 2023 |
| TML Service Centre Ltd | Wholesale & retail | 2023 |
| TMP Vehicles Ltd | Wholesale & retail | 2021 |
| TMS Plant Services Limited | Construction | 2020 |
| TNG Tax Ltd | Professional & scientific | 2022 |
| TNT Energy Ltd | Construction | 2023 |
| Toad Micropub Ltd | Hospitality | 2025 |
| Toastielabs Ltd | Information & communication | 2022 |
| Today Shawarma (NE) Ltd | Hospitality | 2025 |
| Todd and CUE (RMS) Limited | Administrative & support | 2001 |
| Todd and CUE 2017 Limited | Extraterritorial | 2017 |
| Together for Gateshead CIC | Administrative & support | 2025 |
| TOL Contracts Limited | Construction | 1998 |
| TOM Ferguson (Motor Engineers) Limited | Wholesale & retail | 1985 |
| Tomahawk Steakhouse (Darlington) Limited | Hospitality | 2019 |
| Tomasz Widera Ltd | Transport & logistics | 2025 |
| Tompion Commercial Limited | Construction | 2024 |
| Tompion Developments Limited | Construction | 2023 |
| Tompion Homes Limited | Construction | 2023 |
| Tony Carter Transport Limited | Transport & logistics | 2013 |
| Tony Hopkins Entertainments Limited | Arts & recreation | 2015 |
| Toon Hardware Limited | Wholesale & retail | 2025 |
| Toon TAN Ltd | Other services | 2022 |
| Toontelly Limited | Information & communication | 2011 |
| Toonup Ltd | Wholesale & retail | 2024 |
| Tooth Studio Ltd | Health & social care | 2026 |
| Top Barbers (NE) Ltd | Other services | 2025 |
| Top of the Props - North East Ltd | Other services | 2024 |
| Top Smiles Ltd | Health & social care | 2018 |
| Top Top Pizza Ltd | Hospitality | 2024 |
| Topa Inspection Ltd. | Construction | 2012 |
| Topfour Investments Ltd | Real estate | 2017 |
| Topmark Healthcare Support Ltd | Administrative & support | 2016 |
| Tori Holdings Ltd | Real estate | 2020 |
| Torque Motorcycles Ltd | Wholesale & retail | 2025 |
| Toscana Pizza Gatehead Ltd | Hospitality | 2025 |
| Toscana Pizza NE8 Ltd | Hospitality | 2023 |
| Total Business Group Limited | Extraterritorial | 2009 |
| Total Business Systems Limited | Extraterritorial | 2009 |
| Total Engineering Services (North East) Limited | Construction | 2016 |
| Total Installs NE Ltd | Construction | 2023 |
| Total International Resources Limited | Manufacturing | 2021 |
| Total Management Solutions Ltd | Households | 2025 |
| Total Processing Control Services Limited | Administrative & support | 2024 |
| Totelec Ltd | Wholesale & retail | 2025 |
| Totely GAS North East Limited | Construction | 2024 |
| Totemise Limited | Extraterritorial | 2019 |
| Touring Shroud Ltd | Arts & recreation | 2024 |
| TOV Construction Ltd | Construction | 2021 |
| Tower and Bridge Ltd | Professional & scientific | 2020 |
| Tower Medical Services Limited | Health & social care | 2020 |
| Town Centre Testing Station Ltd | Wholesale & retail | 2008 |
| Townfield Residential NE Ltd | Real estate | 2024 |
| Toy Secrets Ltd | Wholesale & retail | 2021 |
| Toyab Investments Limited | Real estate | 2024 |
| TPC Beauty Ltd | Wholesale & retail | 2012 |
| TPS Emachines Limited | Manufacturing | 2022 |
| TPS Energy Limited | Manufacturing | 2022 |
| TPS NCL Ltd | Wholesale & retail | 2025 |
| TPS Rail Limited | Manufacturing | 2022 |
| TPV Competition Ltd | Other services | 2025 |
| TRA Property Ltd | Information & communication | 2026 |
| Trackwalk Limited | Real estate | 2002 |
| Tradeconnect Global Ltd | Wholesale & retail | 2024 |
| Trademate Building Supplies Ltd | Wholesale & retail | 2023 |
| Tradeworks Ltd | Wholesale & retail | 2004 |
| Traffic Management UK Services Ltd | Construction | 2018 |
| Trailblazer Homes Ltd | Real estate | 2023 |
| Training in Logistics Ltd | Transport & logistics | 2019 |
| Transcendit EOT Limited | Extraterritorial | 2024 |
| Transcendit Limited | Information & communication | 2000 |
| Transform HR Solutions Ltd | Administrative & support | 2021 |
| Transit Part Specialist’S North East Limited | Wholesale & retail | 2021 |
| Transmit Enterprise Community Interest Company | Professional & scientific | 2010 |
| Transmit Start-Ups Limited | Professional & scientific | 2013 |
| Transport Network Connect Ltd | Professional & scientific | 2023 |
| Transport North East | Administrative & support | 2009 |
| Trasgate Ltd | Other services | 2018 |
| Travellers Rest Limited | Hospitality | 2023 |
| Travelling BEE Company Limited | Wholesale & retail | 2019 |
| Traz Ltd | Health & social care | 2019 |
| Treeni Convenience Limited | Wholesale & retail | 2026 |
| Trends VIP Limited | Wholesale & retail | 2020 |
| Trentino Consultants Ltd | Wholesale & retail | 2023 |
| Trezora Limited | Professional & scientific | 2025 |
| TRI Connections Ltd | Energy | 2024 |
| Tria Consulting Services Ltd | Information & communication | 2025 |
| Tribley Farmlands Limited | Real estate | 2020 |
| Trident Fire Protection and Training Limited | Construction | 2016 |
| Trifanov Ltd | Health & social care | 2018 |
| Trigo Design Limited | Professional & scientific | 2021 |
| Trilogy GAS and Power Ltd | Energy | 2018 |
| Trinity Card Capital Ltd | Wholesale & retail | 2019 |
| Tripak Ltd | Manufacturing | 1979 |
| Tripfiction Limited | Arts & recreation | 2017 |
| Tritouch Ltd | Manufacturing | 2018 |