| Traffic Management 1999 Ltd | Construction | 2025 |
| Traffic Safety Consultants Ltd | Public administration | 2024 |
| Traffic Sign Services Ltd. | Professional & scientific | 2025 |
| Trafford Print Limited | Manufacturing | 1976 |
| Traiano Transport Ltd | Transport & logistics | 2026 |
| TRAIN2BAKE.COM Ltd | Education | 2011 |
| Training and Traffic Services Ltd | Education | 2022 |
| Trainmydarts Ltd | Wholesale & retail | 2026 |
| Tranbart Ltd | Transport & logistics | 2025 |
| Tranmoor Court 1990 Property Management Company Limited | Households | 1991 |
| Trans David ACV Company Ltd | Transport & logistics | 2025 |
| Trans SEV Ltd | Transport & logistics | 2018 |
| Transact Technologies Limited | Wholesale & retail | 1994 |
| Transalpina Ltd | Transport & logistics | 2023 |
| Transand Ltd | Transport & logistics | 2025 |
| Transbary Ltd | Transport & logistics | 2022 |
| Transdek U.K. Limited | Manufacturing | 1997 |
| Transedge Technologies Ltd | Financial services | 2025 |
| Transeuro Flight Ltd | Extraterritorial | 2026 |
| Transfagarasani Transport Ltd | Transport & logistics | 2024 |
| Transformative Minds Ltd | Financial services | 2024 |
| Transit X Logistics Ltd | Transport & logistics | 2024 |
| Transkodo Ltd | Transport & logistics | 2025 |
| Transport Concierge Limited | Wholesale & retail | 2005 |
| Transportmate Ltd | Information & communication | 2026 |
| Transportsnap Limited | Transport & logistics | 2025 |
| Transsgo Ltd | Transport & logistics | 2026 |
| Transylvania Traditions CIC | Education | 2026 |
| Transylvania Trans Limited | Transport & logistics | 2014 |
| Travel Friendly Ltd | Wholesale & retail | 2024 |
| Travel Lens Limited | Information & communication | 2021 |
| Travel Lettings Ltd | Hospitality | 2019 |
| Travel With JOE and Emily Ltd | Administrative & support | 2024 |
| Travellers Rest (Tickhill) Ltd | Hospitality | 2025 |
| Travellers Rest PUB and Kitchen Ltd | Hospitality | 2025 |
| Travelshub Limited | Wholesale & retail | 2024 |
| Travis Court Residents Association Limited | Real estate | 1987 |
| Trax Logistics Limited | Transport & logistics | 2025 |
| Treasure House (Bawtry) Limited | Real estate | 1985 |
| Tredstonerfm Ltd | Financial services | 2019 |
| Trefoil Inns Limited | Hospitality | 2025 |
| Tremonti Ltd | Administrative & support | 2020 |
| Trend SPOT2 Limited | Wholesale & retail | 2024 |
| Trendoraa Limited | Wholesale & retail | 2026 |
| Trentside (Gainsborough) Management Company Limited | Households | 2004 |
| Trentside Ltd | Real estate | 2019 |
| Treny Limited | Wholesale & retail | 2025 |
| Treo Recruitment Limited | Administrative & support | 2021 |
| Treo Site Solutions Ltd | Administrative & support | 2025 |
| Tret Ltd | Construction | 2020 |
| Trevallyn Limited | Professional & scientific | 2020 |
| Trevalon Capital Ltd | Extraterritorial | 2026 |
| Trevor Keith Langfield Ltd | Households | 2025 |
| Triangulate Health Ltd | Administrative & support | 2017 |
| Tribarnes Holdings Limited | Real estate | 2025 |
| Trickle UP Ltd | Professional & scientific | 2019 |
| Triglav Ltd | Wholesale & retail | 2025 |
| Trilook Limited | Extraterritorial | 1999 |
| Trimad Sign & Display Ltd | Manufacturing | 2015 |
| Trinity Consortium Limited | Manufacturing | 2015 |
| Trinity House (Harrogate) Management Company Limited | Households | 2023 |
| Trinity Self Drive Ltd | Administrative & support | 2020 |
| Trinity&Neo Transport Ltd | Transport & logistics | 2025 |
| Trio Touch Ltd | Administrative & support | 2025 |
| Trip OUT Electronic Goods Wholesaler Limited | Manufacturing | 2026 |
| Triphi Limited | Administrative & support | 2006 |
| Triple D Resources Limited | Wholesale & retail | 2025 |
| Tripled Planning Services Limited | Professional & scientific | 2025 |
| Tripleweb Limited | Information & communication | 2024 |
| Trish Kingham Consulting Ltd | Professional & scientific | 2018 |
| Tristar MSP Limited | Information & communication | 2019 |
| Triteck Limited | Manufacturing | 2022 |
| Triton Blues and Engineering Ltd | Construction | 2025 |
| Tropic TAN Ltd | Hospitality | 2021 |
| Tropolo Systems Limited | Extraterritorial | 2013 |
| Trowbridge Marine Ltd. | Professional & scientific | 2017 |
| Trowel & Shovel Ltd | Administrative & support | 2025 |
| TRP Communications Ltd | Professional & scientific | 2024 |
| TRT Portfolio Ltd | Real estate | 2024 |
| Truck Commercial Ltd | Wholesale & retail | 2017 |
| Truck Crane Hydraulics Limited | Extraterritorial | 2002 |
| Truck Hydraulics Limited | Manufacturing | 2002 |
| Truck Rental Limited | Wholesale & retail | 2025 |
| TRUCK18 Movers Ltd | Transport & logistics | 2025 |
| Trucker Carl Ltd | Transport & logistics | 2025 |
| Truckery Ltd | Transport & logistics | 2025 |
| Trucking Good Productions Ltd | Transport & logistics | 2022 |
| True Aesthetics (Doncaster) Ltd | Other services | 2019 |
| True Axis Ltd | Health & social care | 2026 |
| True Gold Ltd | Arts & recreation | 2019 |
| True Horizon Community CIC | Education | 2026 |
| Truewords Limited | Public administration | 2020 |
| Truffle Group Limited | Wholesale & retail | 2019 |
| Trumax Building Ltd | Construction | 2011 |
| Trumax Homes Ltd | Real estate | 2011 |
| Trumax Productions Ltd | Construction | 2021 |
| Trupart Limited | Wholesale & retail | 1985 |
| Trust Logistic Ltd | Transport & logistics | 2021 |
| Trustclean Commercial Contract Cleaning Limited | Administrative & support | 2017 |
| Trustclean Food Hygiene & Consultancy Services Limited | Administrative & support | 2017 |