| Tride & Square Construction Limited | Construction | 2024 |
| Trident Property Investments Ltd | Real estate | 2021 |
| Trifortune Limited | Financial services | 2025 |
| Triggertrade Limited | Financial services | 2026 |
| Trigon Media Limited | Information & communication | 2013 |
| Trimega Services Ltd | Professional & scientific | 2026 |
| Trinav Limited | Professional & scientific | 2022 |
| Trinis in London Ltd | Other services | 2014 |
| Trinqoo Transfers Ltd | Transport & logistics | 2024 |
| Trinqus Labs Ltd | Professional & scientific | 2020 |
| Trion Animal Care Limited | Manufacturing | 2025 |
| Trion Healthcare Limited | Wholesale & retail | 2025 |
| Triple a Management Ltd | Real estate | 2020 |
| Triple FM Limited | Administrative & support | 2024 |
| Triple M Healthcare Services Ltd | Health & social care | 2024 |
| Triple Rainbow IT Consulting (UK) Ltd | Information & communication | 2021 |
| Triple Solutions Ltd | Other services | 2017 |
| Tripoint Group Ltd | Professional & scientific | 2026 |
| Trish London Accountants Limited | Professional & scientific | 2024 |
| Triumph Property Consulting Ltd | Real estate | 2024 |
| TRM Builders Limited | Construction | 2013 |
| Troera Ltd | Real estate | 2020 |
| Trojan Asset Ltd | Administrative & support | 2012 |
| Trojan Scaffolding Ltd | Construction | 2005 |
| Trolley Cutz Barber Ltd | Other services | 2025 |
| True Light Global Ltd | Professional & scientific | 2021 |
| True Trusted Therapy Ltd | Health & social care | 2022 |
| Truecore Construction Limited | Professional & scientific | 2025 |
| Trueline Investment Limited | Real estate | 2025 |
| Truemark Travels Ltd | Administrative & support | 2016 |
| Truespin Digital Limited | Information & communication | 2020 |
| Truestone Developments Ltd | Households | 2017 |
| Trusam Limited | Health & social care | 2019 |
| Trust Construct Ltd | Construction | 2026 |
| Trustbridge Limited | Administrative & support | 1971 |
| Trustzone Security Ltd | Administrative & support | 2025 |
| TRY Property Management Ltd | Real estate | 2022 |
| Trygg Health Ltd | Information & communication | 2026 |
| TS Connect World Ltd | Wholesale & retail | 2025 |
| TS Legal Consultancy Ltd | Professional & scientific | 2022 |
| TS1967 Ltd | Hospitality | 2024 |
| TSB One Limited | Information & communication | 2016 |
| TSF Place Ltd | Real estate | 2026 |
| TSM Surrey Properties Ltd | Real estate | 2022 |
| TT 2016 Limited | Professional & scientific | 2016 |
| Ttresidentials Limited | Real estate | 2020 |
| Tuckerfxm Ltd | Information & communication | 2024 |
| Tudor Freehold Ltd | Households | 2021 |
| Tudor Management Company (Sutton) Limited | Households | 1986 |
| Tufail Chemicals UK Limited | Wholesale & retail | 2019 |
| Tufail&Sons Ltd | Transport & logistics | 2021 |
| Turkic Solidarity in Britain Ltd | Health & social care | 2021 |
| Turnbull Homes (Alexandra) Limited | Construction | 2023 |
| Turnbull Homes (ASH Tree Close) Management Company Limited | Households | 2021 |
| Turnbull Homes (ASH Tree) Limited | Construction | 2020 |
| Turnbull Homes (Campden) Limited | Construction | 2017 |
| Turnbull Homes (Church Way) Limited | Construction | 2017 |
| Turnbull Homes (Crawley) Limited | Construction | 2021 |
| Turnbull Homes (Dwelly) Limited | Construction | 2021 |
| Turnbull Homes (Ewell) Limited | Construction | 2021 |
| Turnbull Homes (Feltham) Limited | Construction | 2018 |
| Turnbull Homes (Grange) Ltd | Construction | 2020 |
| Turnbull Homes (Halling) Limited | Construction | 2010 |
| Turnbull Homes (Harewood) Limited | Construction | 2021 |
| Turnbull Homes (Little Hundith) Limited | Construction | 2019 |
| Turnbull Homes (Purley Downs) Limited | Construction | 2023 |
| Turnbull Homes (Rectory) Limited | Construction | 2022 |
| Turnbull Homes (Selborne) Limited | Construction | 2021 |
| Turnbull Homes (Selsdon) Limited | Construction | 2018 |
| Turnbull Homes (Sunnybank) Limited | Construction | 2018 |
| Turnbull Homes (Taplow) Limited | Construction | 2016 |
| Turnbull Homes (Worcester Park) Limited | Construction | 2017 |
| Turnbull Homes (Wyvell) Limited | Construction | 2022 |
| Turnbull Homes Godalming Ltd | Construction | 2021 |
| Turnbull Homes Limited | Construction | 1999 |
| Turnkey Suited Ltd | Real estate | 2026 |
| Turnpower Services Limited | Administrative & support | 1993 |
| Turquoise Cleaning Company Limited | Administrative & support | 2009 |
| Tusha Construction Services Ltd | Construction | 2021 |
| Tutrakan Ltd | Construction | 2015 |
| TV Editing Limited | Information & communication | 2011 |
| TVS Properties Ltd | Real estate | 2019 |
| Tweedplot Limited | Real estate | 1996 |
| Twenty Three Capital Ltd | Administrative & support | 2019 |
| Twinn Tubb Ltd | Administrative & support | 2019 |
| Twins Homecare Limited | Health & social care | 2024 |
| TWJ Properties (Flats) Limited | Real estate | 2019 |
| TWJ Properties Limited | Real estate | 2017 |
| Two Element Consulting Ltd | Administrative & support | 2006 |
| Two Hares Running Limited | Administrative & support | 2015 |
| Two Tribes Communications Limited | Administrative & support | 2026 |
| TXC Properties Ltd | Real estate | 2025 |
| U BNB Ltd | Real estate | 2019 |
| U R Derder Travel Ltd | Administrative & support | 2022 |
| U Turn 4 Car Wash Ltd | Administrative & support | 2021 |
| U&A Consulting Ltd | Information & communication | 2014 |
| U&A Properties Ltd | Real estate | 2020 |
| U.K. Asia Global Ltd | Financial services | 2015 |
| U.K. Medical Development Associates | Health & social care | 2016 |
| UB Retail Ltd | Wholesale & retail | 2023 |