| Trinity Wealth Management Limited | Financial services | 2001 |
| Trinity WM Limited | Financial services | 2012 |
| Trio Construct Ltd | Construction | 2019 |
| Triot Ltd | Information & communication | 2025 |
| Trip (London) Limited | Wholesale & retail | 2019 |
| Trip to World Ltd | Administrative & support | 2025 |
| Triple H Electrical Services Limited | Other services | 2013 |
| Triple M Investments (UK) Ltd | Real estate | 2020 |
| Triple S Plastering Ltd | Construction | 2023 |
| Triplebond Limited | Financial services | 2001 |
| Tripmate Tours Ltd | Transport & logistics | 2025 |
| Trirock Limited | Construction | 2015 |
| Tris Construction Ltd | Construction | 2026 |
| Trishan Patel Coaching Ltd | Arts & recreation | 2019 |
| Tristar Interactive Limited | Extraterritorial | 1995 |
| Tristar Television Limited | Information & communication | 1995 |
| Triumph Luton Ltd | Real estate | 2017 |
| Triviumone Ltd | Professional & scientific | 2025 |
| TRK Transport Ltd | Transport & logistics | 2016 |
| Trkp Ltd | Wholesale & retail | 2025 |
| TRL Transport Limited | Wholesale & retail | 2016 |
| Troka's Plumbing & Heating Ltd | Construction | 2024 |
| Troll Ltd | Wholesale & retail | 2026 |
| Tropical Fusion International Ltd | Wholesale & retail | 2024 |
| Tropical Planet Ltd | Wholesale & retail | 2025 |
| Tropical Salon Limited | Other services | 2023 |
| Trotts IT Consultancy Ltd | Information & communication | 2020 |
| Trovica Limited | Wholesale & retail | 2025 |
| Trowbridge Solutions Limited | Information & communication | 2008 |
| TRP Productions Limited | Information & communication | 2023 |
| TRS Windmill Limited | Other services | 2004 |
| TRU Automation Ltd | Construction | 2021 |
| Truck Lane Ltd | Transport & logistics | 2017 |
| Truck Logistics Ltd | Transport & logistics | 2022 |
| Trucks 4 ALL Ltd | Wholesale & retail | 2025 |
| True Dreams Ltd | Administrative & support | 2025 |
| True Finish Paving & Risen Ltd | Administrative & support | 2025 |
| True Global Markets Ltd | Administrative & support | 2024 |
| True Renovations Ltd | Construction | 2026 |
| Truecolour Imaging Ltd | Professional & scientific | 2006 |
| Trueeliteshop Ltd | Wholesale & retail | 2025 |
| Trueline Electrical Ltd | Construction | 2019 |
| Truestone Estates Ltd | Real estate | 2025 |
| Trumechanic Ltd | Wholesale & retail | 2017 |
| Trumpf Limited | Manufacturing | 1974 |
| Trust Electrical Installation Ltd | Construction | 2020 |
| Trust Tech Solutions Limited | Wholesale & retail | 2025 |
| Trust Trading Limited | Wholesale & retail | 2016 |
| Trusted Business Advice Alliance Ltd | Administrative & support | 2025 |
| Trustee Real Estate Ltd | Real estate | 2025 |
| Trustees Unlimited LLP | | 2009 |
| Trustgo Logistics Ltd | Transport & logistics | 2025 |
| Trustlink Solutions Ltd | Information & communication | 2024 |
| Truth & Lies Limited | Professional & scientific | 2016 |
| Try-Luna Limited | Financial services | 2024 |
| Trycatch Solutions Ltd | Wholesale & retail | 2026 |
| Tryumph Ltd | Information & communication | 2019 |
| TS Chicks Ltd | Hospitality | 2025 |
| TS Renewable Heating Solutions Limited | Construction | 2026 |
| TSB Housing Group Ltd | Real estate | 2023 |
| Tsej Properties Ltd | Real estate | 2020 |
| Tsesakal Ltd | Information & communication | 2015 |
| TSG Capital Ltd | Financial services | 2022 |
| TSI Homes Limited | Real estate | 2020 |
| TSJ Healthcare Limited | Health & social care | 2014 |
| TSM International Solutions Ltd | Health & social care | 2013 |
| Tsotso Limited | Health & social care | 2024 |
| TSS Care UK Ltd | Professional & scientific | 2023 |
| TSS Foods Limited | Hospitality | 2026 |
| TT Bullion Ltd | Manufacturing | 2023 |
| TT GEN Cloud Ltd | Professional & scientific | 2024 |
| TT Lettings Ltd | Households | 2025 |
| Ttles Ltd | Wholesale & retail | 2026 |
| TTM ID Limited | Professional & scientific | 2019 |
| TTM RU Ltd | Administrative & support | 2022 |
| TTP IND Ltd | Construction | 2026 |
| TTT Property Management Ltd | Households | 2025 |
| Tttripplecare Limited | Other services | 2017 |
| Tubeworks Scaffolding Ltd | Construction | 2022 |
| Tucker Hairdressing Ltd | Other services | 2022 |
| Tudor Classic Car Accessories Limited | Wholesale & retail | 2021 |
| Tudor Utility Excavations Ltd | Construction | 2026 |
| Tuesday Dumpleton Ltd | Hospitality | 2021 |
| Tuhazul Investments Ltd | Financial services | 2020 |
| TUI Airways Limited | Transport & logistics | 1947 |
| TUI Aviation Asset Company Limited | Administrative & support | 2022 |
| TUI Aviation Services Limited | Extraterritorial | 2020 |
| TUI Group Fleet Finance Limited | Administrative & support | 2017 |
| TUI Group UK Healthcare Limited | Extraterritorial | 2008 |
| TUI Group UK Trustee Limited | Extraterritorial | 2011 |
| TUI Ireland Limited | Other services | 1988 |
| TUI Musement UK Holding Limited | Professional & scientific | 2011 |
| TUI Northern Europe Limited | Professional & scientific | 1998 |
| TUI Pensions Restricted SPV Limited | Financial services | 2024 |
| TUI Ship Financing Limited | Financial services | 2025 |
| TUI Travel Aviation Finance Limited | Administrative & support | 2009 |
| TUI Travel Common Investment Fund Trustee Limited | Extraterritorial | 2009 |
| TUI Travel Group Solutions Limited | Information & communication | 1999 |
| TUI Travel Holdings Limited | Professional & scientific | 2008 |
| TUI Travel Limited | Professional & scientific | 2007 |