| Tracy Park (Holdings) Limited | Financial services | 2015 |
| Tracy Park Limited | Hospitality | 2015 |
| Trade AID (UK) Limited | Extraterritorial | 1998 |
| Trade AID International Limited | Wholesale & retail | 2001 |
| Trade Beds Direct Limited | Wholesale & retail | 2018 |
| Trade Desk UK Limited | Wholesale & retail | 2006 |
| Trade Glazing Systems Ltd | Wholesale & retail | 2013 |
| Trade Market Ltd | Wholesale & retail | 2018 |
| Trade Plate Movers Ltd | Wholesale & retail | 2019 |
| Trade Print Embroidery Ltd | Wholesale & retail | 2025 |
| Trademark Products Ltd | Wholesale & retail | 2002 |
| Tradersherald Ltd | Financial services | 2022 |
| Tradeweb Design Ltd | Information & communication | 2024 |
| Tradewinds Media Limited | Information & communication | 2015 |
| Tradigo Limited | Wholesale & retail | 2018 |
| Trading Guards Ltd | Wholesale & retail | 2025 |
| Trading Standards South East Limited | Public administration | 2004 |
| Traditional Developments Ltd | Construction | 2024 |
| Traditional Rainwater Systems Ltd | Construction | 2018 |
| Trafford Road Investment Ltd | Real estate | 2017 |
| Trailers & More Ltd | Financial services | 2013 |
| Trails and Vines Ltd | Administrative & support | 2018 |
| Train for Life Fitness & Nutrition Ltd | Other services | 2012 |
| Training and Apprenticeships in Construction Limited | Professional & scientific | 2012 |
| Training Logic Limited | Health & social care | 2018 |
| Training Shed Family Ltd | Arts & recreation | 2019 |
| Training Works 4 U Ltd. | Education | 2012 |
| Traitseq Ltd | Professional & scientific | 2023 |
| Trakings & Tyres Ltd | Wholesale & retail | 2024 |
| Tramore Management Limited | Hospitality | 2009 |
| Tranquil Estates Ltd | Real estate | 2023 |
| Transafe Logistics Limited | Transport & logistics | 2004 |
| Transbaltic Logistics Ltd | Transport & logistics | 2018 |
| Transcribe Copier Systems Limited | Wholesale & retail | 1983 |
| Transcribe Limited | Administrative & support | 1990 |
| Transform Care Limited | Health & social care | 2017 |
| Transform Manage Estates Ltd | Real estate | 2020 |
| Transformelt Ltd | Education | 2017 |
| Transforming Local Communities C.I.C. | Water & waste | 2019 |
| Translational Diagnostics Ltd | Health & social care | 2020 |
| Transluna Limited | Transport & logistics | 2019 |
| Transport & Haulage Ltd | Transport & logistics | 2022 |
| Transport AVM Ltd | Transport & logistics | 2020 |
| Transport Consulting Services (East Anglia) Limited | Transport & logistics | 2013 |
| Transport Logistics UK Ltd | Wholesale & retail | 2018 |
| Transpose Technology Limited | Professional & scientific | 1993 |
| Transrussiauk Limited | Administrative & support | 2018 |
| Trappers Holdings Limited | Financial services | 2024 |
| Traquair Holdings Limited | Real estate | 2024 |
| Tratem Ltd | Information & communication | 2025 |
| Trautmans Ltd | Professional & scientific | 2025 |
| Travells Wind Service Ltd | Professional & scientific | 2024 |
| Travinet Limited | Information & communication | 2015 |
| TRB (UK) Limited | Construction | 2002 |
| TRC Care Staffing Ltd | Health & social care | 2021 |
| TRC Healthcare Staffing Agency Ltd | Health & social care | 2019 |
| Trco Ltd | Information & communication | 2023 |
| Treasure Naturals Limited | Wholesale & retail | 2025 |
| Treat Norwich Limited | Health & social care | 2016 |
| Trebiffen Holdings Limited | Professional & scientific | 2014 |
| Treburne Financial Services Ltd | Financial services | 2025 |
| Tredgett Ltd | Administrative & support | 2022 |
| Tree Associates Ltd | Professional & scientific | 2014 |
| Treecore Limited | Agriculture & fishing | 2024 |
| Treefrog Ltd | Professional & scientific | 2021 |
| Treehouse Children and Families Centre | Education | 2002 |
| Treekly Group Ltd | Information & communication | 2019 |
| Treerunner ARB Limited | Other services | 2017 |
| Treerunner Holdings Limited | Financial services | 2017 |
| Trees OR Gardens Ltd | Administrative & support | 2023 |
| Tregantle Property Ltd | Real estate | 2020 |
| Trellisian Limited | Construction | 1977 |
| Treltec Ltd | Manufacturing | 2025 |
| Trench Farm Eggs Ltd | Agriculture & fishing | 2023 |
| Trend Enterprises Ltd | Wholesale & retail | 2012 |
| Trendiko Solutions Ltd | Wholesale & retail | 2025 |
| Trendylicious Ltd | Wholesale & retail | 2025 |
| Treow Forest School CIC | Education | 2025 |
| Trett Films Limited | Information & communication | 2019 |
| Trett Phillips Residentail Lettings Ltd. | Real estate | 2016 |
| Trett Phillips Residential Sales Ltd. | Real estate | 2016 |
| Trevaskis Builders Limited | Construction | 2007 |
| Trevelyan Consultancy Ltd | Professional & scientific | 2025 |
| Trevor Sadd Associates Limited | Professional & scientific | 2005 |
| Trevor White Roses LLP | | 2023 |
| Trevor Wright Electrical Limited | Construction | 2010 |
| Trevu Ltd | Construction | 2022 |
| Tri-Colour Holdings Ltd | Financial services | 2025 |
| Triangle Amusements Limited | Arts & recreation | 1940 |
| TRIANGUL8 Solutions Limited | Extraterritorial | 2017 |
| Triarch Ventures Limited | Financial services | 2025 |
| Trias Consult Ltd | Administrative & support | 2016 |
| Triaura Ltd | Arts & recreation | 2026 |
| Tribal Bay Limited | Financial services | 2025 |
| Tribo-Technology Ltd | Wholesale & retail | 2025 |
| Tricker Blackie Associates Limited | Professional & scientific | 2002 |
| Tricor Homes Ltd | Construction | 2022 |
| Tricote Metal Finishings Limited | Manufacturing | 1987 |
| Tridarn Limited | Real estate | 2009 |
| Trident Cars Ltd | Wholesale & retail | 2013 |