| Transmuted CIC | Information & communication | 2024 |
| Transparent Design Limited | Administrative & support | 2008 |
| Transpiotr Ltd | Transport & logistics | 2020 |
| Transplant Haulage Ltd | Transport & logistics | 2019 |
| Transport Advisory Partners Limited | Professional & scientific | 2024 |
| Transport Fabrications Limited | Manufacturing | 1989 |
| Transport Planning (York) Limited | Professional & scientific | 2014 |
| Travel Keepsakes Limited | Wholesale & retail | 2026 |
| Travel Monkey Holiday Lets Ltd | Real estate | 2021 |
| Travel Yorkshire Ltd | Transport & logistics | 2025 |
| TRC Group (UK) Ltd | Financial services | 2024 |
| Trcs (UK) Limited | Administrative & support | 2011 |
| Treasure Island Playcentre Limited | Professional & scientific | 2005 |
| Treatment Films Limited | Information & communication | 2003 |
| Treats for YOU Limited | Manufacturing | 2004 |
| Trebro (UK) Ltd | Manufacturing | 2003 |
| Tree & Conifer Removal Limited | Agriculture & fishing | 2016 |
| Tree Diagnostics Ltd | Extraterritorial | 2016 |
| Tree Frog Holdings Limited | Financial services | 2024 |
| Treehorn Media Limited | Information & communication | 2013 |
| Trees and Seeds Limited | Agriculture & fishing | 2024 |
| Treeship Limited | Wholesale & retail | 1979 |
| Treesy Green Limited | Other services | 2020 |
| Trehenlis Gardens (Helston) Management Company Limited | Households | 2024 |
| Trelawny Place (Felixstowe) Residents Management Company Limited | Households | 2021 |
| Trembling Madness Lendal Ltd | Hospitality | 2018 |
| Trembling Madness Ltd | Hospitality | 2010 |
| Trembling Madness Stonegate Ltd | Hospitality | 2024 |
| Trencham Associates Limited | Information & communication | 2008 |
| Trent Park Regeneration Limited | Professional & scientific | 1998 |
| Trent Valley Home Improvements Limited | Construction | 2024 |
| Trentholme House Management Company Limited | Households | 2005 |
| Trevelyan Grange (Morpeth) Residents Management Company Limited | Real estate | 2020 |
| Trevethan Meadows Liskeard Management Company Limited | Households | 2013 |
| Trevithick Manor Park (Newquay) Management Company Limited | Households | 2024 |
| Trevor Hopkins Consulting Services Limited | Professional & scientific | 2010 |
| Trevor Smith Landscapes Ltd. | Administrative & support | 2001 |
| Trevor Watson Associates Limited | Other services | 2011 |
| Tria Management Ltd | Manufacturing | 2023 |
| Triagri Limited | Agriculture & fishing | 2023 |
| Tribe Fit Community Limited | Arts & recreation | 2019 |
| Tricia Elliott Ceramics Ltd | Manufacturing | 2016 |
| Tricolor York Limited | Hospitality | 2022 |
| Trident Engineering Excellence Limited | Administrative & support | 2025 |
| Trident Tree Works Limited | Administrative & support | 2024 |
| Trig Brewery Limited | Manufacturing | 2023 |
| Trigfan Park Limited | Financial services | 2018 |
| Trilogy Toys Ltd | Wholesale & retail | 2026 |
| Trinacria York Ltd | Hospitality | 2011 |
| Trinity (TDI) Ltd | Real estate | 2014 |
| Trinity Close (Stockton on the Forest) Management Company Limited | Households | 2017 |
| Trinity Court Management York Limited | Households | 1996 |
| Trinity Fields (Clacton) Residents Management Company Limited | Households | 2024 |
| Trinity House (York) Management Company Limited | Real estate | 2008 |
| Trinity House Developments Limited | Real estate | 1995 |
| Trinity Pastures (Calvert Lane Hull) Residents Management Company Limited | Households | 2022 |
| Trinity Services (U.K.) Limited | Construction | 1986 |
| Trinityone (Leeds) Limited | Construction | 2002 |
| Trio Traders Ltd | Wholesale & retail | 2025 |
| Triple 8 Beverages Ltd | Extraterritorial | 2020 |
| Triple Purple Ltd | Construction | 2022 |
| Triple Twelve Limited | Other services | 2020 |
| TRIPLE6CUSTOMS Ltd | Information & communication | 2024 |
| Tripolitana Property Limited | Real estate | 2025 |
| Tripsync Limited | Information & communication | 2025 |
| Tristone Solutions Limited | Information & communication | 2019 |
| Trivexa Ltd | Professional & scientific | 2024 |
| Trix Agency Limited | Information & communication | 2024 |
| Trjs Trading Ltd | Wholesale & retail | 2024 |
| Tropic Beauty (York) Limited | Wholesale & retail | 2019 |
| Trove Consulting Limited | Professional & scientific | 2025 |
| TRU Holdings Ltd | Real estate | 2025 |
| TRU Network Ltd | Information & communication | 2024 |
| TRU North Construction Ltd | Construction | 2025 |
| TRU Services Ltd | Construction | 2025 |
| True Fit Joinery Limited | Construction | 2011 |
| Truekind Ltd | Other services | 2025 |
| Truelove Properties Ltd | Construction | 2019 |
| Trueman Homes York Ltd | Real estate | 2025 |
| Truetase Creations Ltd | Manufacturing | 2025 |
| Truong & Co 2 Limited | Other services | 2024 |
| Truong & Co Limited | Other services | 2024 |
| Trustbarista Ltd | Wholesale & retail | 2025 |
| Trustbuild (Northern) Ltd | Wholesale & retail | 2007 |
| Trustist Franchising Limited | Administrative & support | 2023 |
| Trustist Limited | Professional & scientific | 2014 |
| Trustist Payments Limited | Information & communication | 2024 |
| Trustmarque Solutions Limited | Information & communication | 1987 |
| Trustspan Timber Engineering Limited | Manufacturing | 1976 |
| Truvanta Ltd | Wholesale & retail | 2025 |
| Trvxcy Ltd | Wholesale & retail | 2026 |
| TRY Onebox Ltd | Wholesale & retail | 2023 |
| Tryall Developments Limited | Extraterritorial | 1961 |
| TS Fire Solutions Ltd | Professional & scientific | 2023 |
| TS Network Property Limited | Real estate | 2021 |
| TS Network Services Limited | Information & communication | 2017 |
| TS Parsons Property Holdings Limited | Real estate | 2019 |
| TS Personal Training & Nutrition Ltd | Arts & recreation | 2021 |
| TS PT Academy Ltd | Education | 2024 |
| Tscgb LLP | | 2026 |