| Travel With Daysack Ltd | Administrative & support | 2024 |
| Travis & Arnold Limited | Extraterritorial | 1982 |
| Travis Group Limited | Extraterritorial | 1916 |
| Travis Limited | Extraterritorial | 1948 |
| Travis Perkins (Properties) Limited | Construction | 1949 |
| Travis Perkins Capital Partner Limited | Extraterritorial | 2010 |
| Travis Perkins Financing Company NO.3 Limited | Professional & scientific | 2010 |
| Travis Perkins Group Holdings Limited | Financial services | 2020 |
| Travis Perkins Merchant Holdings Limited | Professional & scientific | 2018 |
| Travis Perkins P&H Group Holdings Limited | Extraterritorial | 2020 |
| Travis Perkins PLC | Wholesale & retail | 1964 |
| Travis Perkins Trading Company Limited | Wholesale & retail | 1962 |
| Travon Logistics Ltd | Transport & logistics | 2025 |
| Traymark Components Limited | Administrative & support | 1997 |
| Trbird Ltd | Information & communication | 2025 |
| TRE Tech Limited | Information & communication | 2016 |
| Treadaway General Services Ltd | Administrative & support | 2014 |
| Treadhigh Limited | Transport & logistics | 2019 |
| Treasure MIX Ltd | Wholesale & retail | 2024 |
| Treasure Services Limited | Professional & scientific | 2015 |
| Treats Kids Limited | Wholesale & retail | 2026 |
| Treats Studios Limited | Manufacturing | 2022 |
| Treemendous Storage Ltd | Transport & logistics | 2022 |
| TREENAGH11 Ltd | Professional & scientific | 2011 |
| Treetop Rentals Ltd | Real estate | 2022 |
| Tremence Ltd | Other services | 2026 |
| Tremendous Builders Ltd | Construction | 2025 |
| Trenchartax Ltd | Wholesale & retail | 2015 |
| Trenchless Consultants Limited | Construction | 2016 |
| Trend Marquees Limited | Administrative & support | 2015 |
| Trendset Productions Limited | Other services | 2013 |
| Trendy Mays Ltd | Wholesale & retail | 2025 |
| Trendypx Ltd | Wholesale & retail | 2026 |
| Trenlines Ltd | Financial services | 2022 |
| Trennery's Plumbing & Heating Limited | Construction | 2021 |
| Trent Developments Limited | Construction | 2003 |
| Trent Software Limited | Professional & scientific | 1987 |
| Tres Angelos Tapas Bar Ltd | Hospitality | 2018 |
| Tres Professionals Ltd | Financial services | 2014 |
| Tres-Bon Field Event Management Ltd | Hospitality | 2025 |
| Tresh Ltd | Wholesale & retail | 2025 |
| Trevanna London, Limited | Arts & recreation | 2019 |
| Trevanova Limited | Wholesale & retail | 2025 |
| Trevarno Ltd | Administrative & support | 2015 |
| Trevel Limited | Professional & scientific | 2019 |
| Trevor Burke Technology Limited | Information & communication | 1986 |
| Trewards Consulting Limited | Professional & scientific | 2014 |
| TRI Fire Holdco Ltd | Financial services | 2024 |
| TRI Fire Holdings Limited | Financial services | 2024 |
| TRI Fire Limited | Administrative & support | 2020 |
| TRI Metal Works Ltd | Manufacturing | 2025 |
| Tri-Bond Roofing Limited | Construction | 2013 |
| Triad Limited | Arts & recreation | 1994 |
| Triaena Ltd | Construction | 2023 |
| Triangle Ealing Limited | Administrative & support | 1990 |
| Triangle Estate & Petroleum Limited | Professional & scientific | 1990 |
| Triangle Group Holdings Limited | Administrative & support | 1992 |
| Tribe Massage Limited | Health & social care | 2020 |
| Trichosphere Ltd | Education | 2025 |
| Trident Brickwork Limited | Construction | 2016 |
| Trident Mortar Limited | Wholesale & retail | 2023 |
| Trident Property Portfolio Limited | Real estate | 2020 |
| Triformica Limited | Manufacturing | 2012 |
| Tril Construction Ltd | Construction | 2018 |
| Trilight Estates Limited | Real estate | 2023 |
| Trillblack Ltd. | Wholesale & retail | 2023 |
| Trilogy Active Ltd | Arts & recreation | 2011 |
| Trim & Proper Tree Surgeons Ltd | Agriculture & fishing | 2025 |
| Trimarco & Co Limited | Hospitality | 2019 |
| Trimax Mowing Systems Limited | Wholesale & retail | 1998 |
| Trimetria Limited | Construction | 2023 |
| Trina's Wines Limited | Wholesale & retail | 2009 |
| Trinity Engineering (Northampton) Limited | Professional & scientific | 1982 |
| Trinity Gate (ST Lukes) Management Company Limited | Households | 2008 |
| Trinity Green Cotswold Mews Management Company Limited | Households | 2009 |
| Trinity Land Limited | Agriculture & fishing | 1994 |
| Trinity Motors (Bond Street) Limited | Administrative & support | 1968 |
| Trinity Operations Limited | Financial services | 2021 |
| Trinity Spire Estates Limited | Real estate | 1995 |
| Trinity Valeting Services Ltd | Other services | 2015 |
| Trio DRY Cleaners Ltd | Other services | 2017 |
| Triocon Limited | Construction | 2021 |
| Triple a SPV Ltd | Real estate | 2020 |
| Triple Aces Pet Supplies Ltd | Wholesale & retail | 2021 |
| Triple C Homes Ltd | Real estate | 2025 |
| Triple O Medical Limited | Health & social care | 2022 |
| Triple R Consultancy Ltd | Information & communication | 2023 |
| Triple T Retro Ltd | Wholesale & retail | 2023 |
| Tripod Crest Group Limited | Construction | 2003 |
| Tripod Crest Holdings Limited | Financial services | 2021 |
| Tripps Yard Residents Management Company Limited | Households | 2024 |
| Tripr Ltd | Administrative & support | 2018 |
| Triquetra Properties Ltd | Real estate | 2021 |
| Trish Health Care Ltd | Health & social care | 2018 |
| Tristar Stationery Limited | Manufacturing | 1988 |
| Tritax Big Box Developments (Datacentres) Ltd | Financial services | 2026 |
| Tritax Big Box Developments (Land) LLP | | 2013 |
| Tritax Big Box Developments (Midlands) Ltd | Financial services | 2017 |
| Tritax Big Box Developments (Northampton) LLP | | 2014 |
| Tritax Big Box Developments Holdco 1 Ltd | Construction | 2014 |