| Treetops Court RTM Company Limited | Real estate | 2009 |
| Trego Global Ltd | Wholesale & retail | 2025 |
| Trending Real Estate Ltd | Real estate | 2024 |
| Trendpicks Ltd | Wholesale & retail | 2020 |
| Trendz Entertainment Ltd | Arts & recreation | 2025 |
| Treniq Ltd | Wholesale & retail | 2014 |
| TRG Arts Limited | Professional & scientific | 2015 |
| Trgp Ltd | Administrative & support | 2013 |
| Triangle House Management Ltd | Households | 1993 |
| Triangle Properties Group Ltd | Real estate | 2023 |
| Tribal ZOO Limited | Wholesale & retail | 2023 |
| Tricon Associates Limited | Information & communication | 2024 |
| Trident Holdings Trading Limited | Real estate | 2018 |
| Trieps Ltd | Hospitality | 2021 |
| Trilium Limited | Education | 2016 |
| Trilogy Assets Limited | Financial services | 2020 |
| Trimz Ltd | Other services | 2020 |
| Tripathy Reality Limited | Real estate | 2024 |
| Triquetra Holdings Ltd | Financial services | 2025 |
| Triquetra Roofing & Waterproofing Ltd | Construction | 2025 |
| Trish Mcloughlin Consulting Limited | Professional & scientific | 2021 |
| Trivium Investment Ltd | Financial services | 2019 |
| TRL Music Limited | Information & communication | 2005 |
| TRM Electrical Distributors | | 1999 |
| TRM Ventures Limited | Real estate | 2025 |
| TRO Ltd | Information & communication | 2024 |
| Tropical Swimming Pools Ltd | Construction | 2009 |
| Trowelgood Limited | Construction | 2019 |
| TRP Construction Limited | Construction | 2020 |
| Trump Security Limited | Administrative & support | 2025 |
| Trunorth Corporation Limited | Professional & scientific | 2025 |
| Truscent Ltd | Manufacturing | 2026 |
| Trusted Leaders Limited | Professional & scientific | 2010 |
| Trusttree Consulting Limited | Administrative & support | 2025 |
| TS Restaurant Limited | Hospitality | 2016 |
| Tslv Group Ltd | Construction | 2023 |
| Tslv-Construction Ltd | Construction | 2020 |
| TSP Build Ltd | Construction | 2024 |
| TT Global Property Ltd | Real estate | 2018 |
| TT Transportation Limited | Transport & logistics | 2015 |
| TTE Consultancy Limited | Professional & scientific | 2018 |
| TTL Property Investments Ltd | Real estate | 2025 |
| Tudor Capital (U.K.), L.P. | | 1994 |
| Tudor John (2019) LLP | | 2012 |
| Tudor John Limited | Professional & scientific | 2018 |
| Tudor Palm Properties Limited | Real estate | 2018 |
| Tumber Livery Ltd | Agriculture & fishing | 2006 |
| Tunes for Tots Limited | Education | 2023 |
| Turfs UP Surrey Limited | Construction | 2018 |
| Turner Private Office Limited | Financial services | 2018 |
| Turner Wealth & Consultancy Limited | Financial services | 2018 |
| Turnkey Manufacturing Limited | Wholesale & retail | 2004 |
| Turnkey Southeast Limited | Professional & scientific | 2014 |
| Turquoise Advisory Limited | Hospitality | 2015 |
| Turvey Storage Company Limited | Transport & logistics | 2024 |
| Tuta Learning Limited | Education | 2022 |
| TW Financial Services Ltd | Financial services | 2017 |
| Twelfth MAN Limited | Professional & scientific | 2014 |
| Twenty Twenty HR Ltd | Administrative & support | 2016 |
| Twenty Worple Road Management Limited | Households | 1988 |
| TWENTY20 Community Cricket Limited | Arts & recreation | 2013 |
| TWENTY20 Cricket Company Limited | Arts & recreation | 2011 |
| Twickenham Leisure Limited | Arts & recreation | 1984 |
| Two Brothers Rendering Ltd | Construction | 2026 |
| Two Daughters Limited | Information & communication | 2024 |
| Two FAT Ladies (London) Ltd | Administrative & support | 2025 |
| Two Hundred and Sixty Three Goldhurst Terrace Limited | Real estate | 1982 |
| Two Jays Associates Limited | Professional & scientific | 2014 |
| Two Wheels Good Ltd | Wholesale & retail | 2008 |
| TXE Logistics Ltd | Transport & logistics | 2020 |
| Tyche Strategies Limited | Professional & scientific | 2026 |
| Tyler Haigh Limited | Professional & scientific | 2016 |
| Tyyne Engineers Limited | Professional & scientific | 2013 |
| U a International Limited | Wholesale & retail | 1990 |
| UAL Properties Limited | Real estate | 2025 |
| UAS Business Solutions Ltd | Administrative & support | 2023 |
| Uberology Limited | Professional & scientific | 2013 |
| Ubora Consulting Ltd | Information & communication | 2024 |
| Ubuntu Partners Ltd | Financial services | 2022 |
| UCG Advisory Limited | Professional & scientific | 2025 |
| UK Business Mentoring Limited | Professional & scientific | 2009 |
| UK Credit Solutions Limited | Financial services | 2020 |
| UK Employee Checks Ltd | Administrative & support | 2011 |
| UK Epsom Education Limited | Education | 2021 |
| UK Glazing Partnership Ltd | Wholesale & retail | 2021 |
| UK International Enterprises Limited | Information & communication | 1995 |
| UK LED Sign Ltd | Professional & scientific | 2019 |
| UK Martial Arts Ltd | Arts & recreation | 2013 |
| UK Sino Vocational Education Centre Limited | Education | 2022 |
| UK Surfacings Limited | Construction | 1999 |
| UK Way Trade Ltd | Wholesale & retail | 2017 |
| Ukcan Training Solutions Ltd | Professional & scientific | 2012 |
| Ukick Ltd | Wholesale & retail | 2011 |
| UKU Group Limited | Construction | 2024 |
| Ultimate Automation Holdings Ltd | Financial services | 2021 |
| Ultimate Automation Ltd | Manufacturing | 2008 |
| Ultimate Property Maintenance & Services Ltd | Construction | 2025 |
| Ultiox Ltd | Wholesale & retail | 2024 |
| Ultra High Cleaning Services Ltd | Administrative & support | 2021 |
| Ulysseus Limited | Professional & scientific | 2017 |