| Treasures London Limited | Administrative & support | 2017 |
| Treat Basket Ltd | Wholesale & retail | 2023 |
| Treathut Ltd | Hospitality | 2019 |
| Tree Hatch Limited | Administrative & support | 2019 |
| Tree House Care Ltd | Health & social care | 2025 |
| Treen Tech Co Ltd | Information & communication | 2026 |
| Treetab Limited | Administrative & support | 2025 |
| Tregaron 2008 Limited | Financial services | 2008 |
| Tregaron North West Limited | Construction | 2021 |
| Tregarrick Limited | Real estate | 2024 |
| Trejha Ltd | Information & communication | 2025 |
| Trelec Limited | Construction | 2019 |
| Trena Healthcare Limited | Health & social care | 2024 |
| Trenchard UK Consulting Limited | Administrative & support | 2016 |
| Trend International Ltd | Wholesale & retail | 2025 |
| Trend Tribe Ltd | Wholesale & retail | 2025 |
| Trendboutique Limited | Wholesale & retail | 2024 |
| Trendedge Ltd | Wholesale & retail | 2025 |
| Trendharbor Ltd | Administrative & support | 2024 |
| Trendhive Solution Limited | Professional & scientific | 2025 |
| Trendify Collection Limited | Wholesale & retail | 2024 |
| Trendigo Ltd | Wholesale & retail | 2024 |
| Trendish Mart Ltd | Wholesale & retail | 2025 |
| Trendixa Ltd | Wholesale & retail | 2026 |
| Trendspire Ltd | Wholesale & retail | 2024 |
| Trendtribe Retail Limited | Wholesale & retail | 2024 |
| Trendy Tees FAN Limited | Wholesale & retail | 2024 |
| Trendyempress Ltd | Wholesale & retail | 2025 |
| Trendz Marketing Limited | Administrative & support | 2013 |
| TRENDZ4U Ltd | Wholesale & retail | 2019 |
| Trendzco Ltd | Wholesale & retail | 2025 |
| Trendzcom Ltd | Wholesale & retail | 2025 |
| Tresarium Limited | Financial services | 2015 |
| Trevelyan Gardens Management Limited | Households | 2018 |
| Trhayders Limited | Wholesale & retail | 2020 |
| TRI Electrical Ltd | Construction | 2023 |
| Triamond Foundations Limited | Extraterritorial | 1997 |
| Triangle Property Services Ltd | Construction | 2018 |
| Triarch Accounting Limited | Professional & scientific | 2025 |
| Tribe Logistics Ltd | Transport & logistics | 2026 |
| Triben Limited | Real estate | 2026 |
| Tribetravelor Ltd | Extraterritorial | 2025 |
| Tribuild Group Ltd | Construction | 2026 |
| Tribune Media Group Limited | Manufacturing | 2024 |
| Tribune Media Project Ltd | Information & communication | 2026 |
| Tricon Design Limited | Professional & scientific | 2022 |
| Trident Accountants Ltd | Professional & scientific | 2025 |
| Trident Build Ltd | Construction | 2025 |
| Trident Knightsbridge Ltd | Professional & scientific | 2023 |
| Trident Property Ventures Limited | Real estate | 2021 |
| Trident Residential Ltd | Hospitality | 2023 |
| Trigeo Services Ltd | Energy | 2014 |
| Trikoms Solutions Ltd | Information & communication | 2019 |
| Trilixr CBD Limited | Wholesale & retail | 2018 |
| Trilogy Contractors Ltd | Construction | 2025 |
| Trim Nation Limited | Other services | 2026 |
| Trim Windows Limited | Manufacturing | 2019 |
| Trimze Limited | Professional & scientific | 2023 |
| Trimzone Ilford Ltd | Other services | 2025 |
| Trinex Global Ltd | Wholesale & retail | 2019 |
| Trinifold Limited | Public administration | 2012 |
| Trinita Group Limited | Wholesale & retail | 2018 |
| Trinity Care London Ltd | Health & social care | 2022 |
| Trinity Circle Limited | Wholesale & retail | 2021 |
| Trinity Cultralink Education Ltd | Education | 2024 |
| Trinity Global Limited | Real estate | 2010 |
| Trinity Pathway College Ltd | Education | 2025 |
| Trinity Support Limited | Hospitality | 2021 |
| Trio Salons Limited | Other services | 2012 |
| Triolux Trading Ltd | Wholesale & retail | 2025 |
| Trip on Ltd | Administrative & support | 2023 |
| Triple Diamond Digital Limited | Administrative & support | 2025 |
| Triple OG Limited | Wholesale & retail | 2025 |
| Tripnest Infinity Ltd | Administrative & support | 2026 |
| Tripoint Recruitment Limited | Administrative & support | 2026 |
| Tripol S Trading & Co Ltd | Wholesale & retail | 2020 |
| Trips N Tours Ltd | Transport & logistics | 2025 |
| Trisha 11 Ltd | Real estate | 2026 |
| Triskele Building and Conservation Limited | Construction | 2023 |
| Trisphere Global Ltd | Wholesale & retail | 2026 |
| Tristar Developments UK Ltd | Real estate | 2024 |
| Tristar Energy UK Limited | Energy | 2017 |
| Tristar Limited | Real estate | 2006 |
| Tristar Properties International Limited | Real estate | 2016 |
| Trisuperstore Ltd | Wholesale & retail | 2019 |
| Triumph Traders Ltd | Wholesale & retail | 2011 |
| Trizeik Limited | Wholesale & retail | 2010 |
| TRK Private Ltd | Wholesale & retail | 2026 |
| Trofin Services Ltd | Administrative & support | 2021 |
| Tronplug Ltd | Wholesale & retail | 2025 |
| Troo Recruitment Ltd | Administrative & support | 2025 |
| Troon Solutions Ltd | Information & communication | 2025 |
| Troon Way Ltd | Health & social care | 2018 |
| Tropi Fruit & VEG Ltd | Wholesale & retail | 2024 |
| Tropic Treasure Limited | Wholesale & retail | 2025 |
| Trsb Ltd | Wholesale & retail | 2022 |
| TRU Recruitment Ltd | Administrative & support | 2021 |
| Truauc Ltd | Wholesale & retail | 2024 |
| Truba Medical Limited | Health & social care | 2019 |
| Trucare Maintenance Ltd | Real estate | 2025 |