| Touchstone Tonewoods Limited | Professional & scientific | 1979 |
| Town Centre Parking Limited | Other services | 1995 |
| Town House(Conversions)Limited | Construction | 1973 |
| Townsends Medica Limited | Health & social care | 1985 |
| Trace Structural Investigations Ltd | Professional & scientific | 2022 |
| Tradcoe Limited | Manufacturing | 2000 |
| Trade Management International Limited | Administrative & support | 2001 |
| Trade Publishing International Limited | Information & communication | 2006 |
| Trade Vehicle Modifications Limited | Wholesale & retail | 2003 |
| Trafalgar Insurance Limited | Financial services | 1907 |
| Trafalgar Land and Marine Engineering Limited | | 1981 |
| Traffic Tech Europe Ltd. | Transport & logistics | 2021 |
| Trailing Edge Limited | Administrative & support | 2003 |
| Training, Consultancy and Practice Ltd | Health & social care | 2008 |
| Transco Blanx Limited | Wholesale & retail | 1994 |
| Transform Landscapes Ltd | Administrative & support | 2002 |
| Transformers & Rectifiers Limited | Manufacturing | 1951 |
| Translift Cranes Limited | Administrative & support | 2007 |
| Translift Logistics Limited | Construction | 2001 |
| Translift Services Limited | Administrative & support | 2007 |
| Transnational Trading Corporation Ltd | Agriculture & fishing | 2018 |
| Transpex Limited | Construction | 2007 |
| Transport Business Services Limited | Transport & logistics | 1992 |
| Transporters Limited | Real estate | 2005 |
| Tranxmit Limited | Information & communication | 2002 |
| Travel and SEE Limited | Health & social care | 2015 |
| Travel Car Services (Purley) Limited | Transport & logistics | 2006 |
| Trayford Limited | Real estate | 2005 |
| Treadlighter Ltd | Professional & scientific | 2007 |
| Treeline Services Limited | Agriculture & fishing | 2002 |
| Treganna Residents Association Limited | Households | 1994 |
| Trendurban Property Management Limited | Households | 1991 |
| Tri-Estates Limited | Real estate | 1986 |
| Tri-Financial Services Limited | Financial services | 2001 |
| Triana Limited | | 1988 |
| Trident Security Group Ltd | Transport & logistics | 2024 |
| Trident Sensors Limited | Professional & scientific | 2004 |
| Tridesant Ltd | Information & communication | 2006 |
| Trifidus Financial Solutions Ltd | Professional & scientific | 2022 |
| Triggerfish Media Ltd | Information & communication | 2007 |
| Trilogy Casting Ltd | Information & communication | 2021 |
| Trimming Homes Limited | Construction | 1995 |
| Trinity CJK Limited | Professional & scientific | 2022 |
| Trio Plus Distribution Limited | Wholesale & retail | 2007 |
| Triple a Consultancy Limited | Professional & scientific | 1990 |
| Triple a Employment Limited | Professional & scientific | 1990 |
| Triple a Entertainment Limited | Professional & scientific | 2004 |
| Triple a Group Limited | Professional & scientific | 1990 |
| Triple a Interim Management Limited | Professional & scientific | 1990 |
| Triple Trading Ltd | Hospitality | 2024 |
| Tripyana Ltd | Administrative & support | 2025 |
| Troco Trading Limited | Professional & scientific | 2002 |
| Tromec Limited | Manufacturing | 1974 |
| Trove Assets Ltd | Real estate | 2017 |
| TRU TAN Limited | Other services | 1999 |
| True High Trading Ltd | Wholesale & retail | 2025 |
| True Insights Limited | Professional & scientific | 2003 |
| True Spirit Limited | Information & communication | 1994 |
| Truecall Group Limited | Information & communication | 2005 |
| Trufaith Limited | Information & communication | 2006 |
| TS Smart Mart Limited | Wholesale & retail | 2025 |
| TS Wire Products Limited | Manufacturing | 2003 |
| Tsaw Management Ltd | Professional & scientific | 2018 |
| TSC Studio Limited | Professional & scientific | 2022 |
| TSF Branded Ltd | Wholesale & retail | 2000 |
| TSR Property Ltd | Real estate | 2018 |
| Tssg Triangle Support Services Group Ltd | Administrative & support | 2020 |
| Tudorglen Limited | Professional & scientific | 2001 |
| Tulia Limited | Wholesale & retail | 2006 |
| Tundra Electrical Limited | Wholesale & retail | 2007 |
| Tungsten Services Ltd | Construction | 2017 |
| Tunnel Ventilation Systems Ltd | Construction | 2009 |
| Turbomachines (Development) Limited | | 1963 |
| Turf Games Limited | Wholesale & retail | 2018 |
| Turn Eleven Consulting Ltd | Professional & scientific | 2021 |
| Turner Court RTM Company Limited | Real estate | 2025 |
| Turner Waymark Limited | Information & communication | 2006 |
| Turrells Limited | Construction | 2006 |
| Tuscan Bay Limited | Administrative & support | 2003 |
| Tutorwithlegj Ltd | Education | 2024 |
| Tvedt Group Limited | Professional & scientific | 1989 |
| TW Project Print Ltd | Manufacturing | 2016 |
| Tweedcross Limited | Households | 1987 |
| Twenty-Eight Portsmouth Road Limited | Professional & scientific | 1959 |
| Twerk'N'Jerk Limited | Hospitality | 2020 |
| Twinerose Limited | Other services | 1974 |
| Two Shores Dialogue Limited | Extraterritorial | 2025 |
| Two the Terrace Limited | Households | 1962 |
| Twofortea Ltd | Professional & scientific | 2013 |
| TWP Wealth Management Ltd | Financial services | 2008 |
| Tyrannus Bible College | Education | 2025 |
| Tyrrells Wood Golf Club Limited | Arts & recreation | 1982 |
| TZ Building & Maintenance Ltd | Construction | 2017 |
| U & S News Food & Wine Limited | Wholesale & retail | 2006 |
| U B Developments Limited | Extraterritorial | 2002 |
| Ubiquity Communications Limited | Information & communication | 2003 |
| UG Care Limited | Health & social care | 2008 |
| UK Car Service Ltd | Transport & logistics | 2005 |
| UK Clone Limited | Professional & scientific | 2007 |
| UK Euro Tours and Travels Limited | Transport & logistics | 2023 |