| Troubleshooter Network Limited | Administrative & support | 2009 |
| Troubleshooter Services Limited | Administrative & support | 2009 |
| Trovie OU Ltd | Wholesale & retail | 2025 |
| Trowsa Plant Rentals Limited | Construction | 1991 |
| Troyan Ltd | Construction | 2019 |
| TRP Associates Limited | Real estate | 2024 |
| TRP Consult Ltd | Wholesale & retail | 2023 |
| TRS 7 Ltd | Real estate | 2026 |
| TRS Cash & Carry Limited | Extraterritorial | 1967 |
| TRS Wholesale Co. Limited | Wholesale & retail | 1987 |
| TRU Impact Co Ltd | Professional & scientific | 2021 |
| True Belief Limited | Real estate | 2004 |
| True Cybele Ltd | Wholesale & retail | 2024 |
| True Promise Limited | Information & communication | 2022 |
| True Red Family 2 Limited | Real estate | 2023 |
| Trueway Education Limited | Professional & scientific | 2025 |
| Truit Sabores Ltd | Hospitality | 2026 |
| Truly Construction Ltd | Real estate | 2023 |
| Truly's Treehouse Ltd | Real estate | 2019 |
| Trump Motors Limited | Wholesale & retail | 2019 |
| Trumpet Glade (Bushey) Residents Company Limited | Real estate | 1987 |
| Truro Marketing Limited | Information & communication | 2022 |
| Trussforma Limited | Manufacturing | 2025 |
| Trust Advantage Ltd | Administrative & support | 2025 |
| Trust an Advisor Limited | Financial services | 2021 |
| Trust Dental Group Ltd | Health & social care | 2016 |
| Trust Property Holdings Ltd | Real estate | 2023 |
| Trust Worthy Wills Limited | Professional & scientific | 2012 |
| Trustbridge Properties Ltd | Real estate | 2025 |
| Truu-U Ltd | Financial services | 2026 |
| TRV Investments Ltd | Real estate | 2016 |
| TRW Enterprises Limited | Financial services | 2021 |
| Trysnet Solutions Ltd | Professional & scientific | 2019 |
| Trywe Limited | Professional & scientific | 2010 |
| TS Building Ltd | Construction | 2019 |
| TS Property Group Ltd | Real estate | 2022 |
| TS Realtor Ltd | Real estate | 2025 |
| TS Taylor Limited | Construction | 2015 |
| TS Trademax Limited | Wholesale & retail | 2021 |
| TSA Network Ltd | Professional & scientific | 2023 |
| TSI Housing Limited | Real estate | 2022 |
| Tslondonn Limited | Professional & scientific | 2021 |
| Tsnc Advisory Ltd | Professional & scientific | 2026 |
| TSP Developments Ltd | Real estate | 2025 |
| TSQ Building Service Ltd | Construction | 2024 |
| Tssvape Ltd | Other services | 2018 |
| Tsuji Kenki Lanka Limited | Wholesale & retail | 2025 |
| Tsukai Studios Ltd | Professional & scientific | 2020 |
| TTA Business Management Ltd | Real estate | 2020 |
| Ttassellab Collection Ltd | Manufacturing | 2020 |
| Tthump Ltd | Wholesale & retail | 2020 |
| TTP Commercial Services Limited | Professional & scientific | 2021 |
| Ttxx Watford Limited | Wholesale & retail | 2024 |
| Tuatara Cypcn Training Limited | Health & social care | 2018 |
| Tubb Limited | Construction | 2014 |
| Tubs Taps & Tiling Ltd | Construction | 2016 |
| Tudar Wine Connect Ltd | Wholesale & retail | 2025 |
| Tudic Ltd | Construction | 2022 |
| Tudor Lettings and Estates (GB) Limited | Real estate | 2025 |
| Tudor Lodge (Freeholds) Limited | Real estate | 1997 |
| Tudor Property Maintenance Limited | Administrative & support | 2006 |
| Tudorken Limited | Real estate | 1977 |
| Tudorpark Holdings Limited | Real estate | 2020 |
| Tuition Junction Limited | Education | 2020 |
| Tulip Propco Ltd | Real estate | 2021 |
| Tulla Projects Limited | Construction | 2014 |
| Tullus Enterprises Limited | Information & communication | 2014 |
| Tulsi Foods Limited | Manufacturing | 2025 |
| Tumble Tots (UK) Limited | Arts & recreation | 1983 |
| TUN Holdings Limited | Real estate | 2020 |
| Tungsten Associates Ltd | Professional & scientific | 2015 |
| TUNGSTEN74 Ltd | Information & communication | 2012 |
| Tuniq Limited | Wholesale & retail | 2019 |
| Tunisiana Ltd | Wholesale & retail | 2026 |
| Tuntex Medical Ltd | Health & social care | 2014 |
| TUR Homes Ltd | Construction | 2025 |
| Turbillon IT Services Ltd. | Information & communication | 2013 |
| Turbine Properties Limited | Real estate | 2017 |
| Turiya Solutions Ltd | Information & communication | 2022 |
| Turnbull Associates Limited | Extraterritorial | 2001 |
| Turnkey Plumbing and Heating LLP | | 2008 |
| Turris Holdings Limited | Financial services | 2020 |
| Turul Trade Ltd | Wholesale & retail | 2023 |
| Tuskerdirect Limited | Administrative & support | 1999 |
| Tutors Services Limited | Education | 2025 |
| Tvastr Ltd | Information & communication | 2011 |
| Tvisha Limited | Real estate | 2017 |
| TVT Cleaning Ltd | Administrative & support | 2023 |
| TWB Property Ltd | Construction | 2022 |
| TWC Contracts Limited | Construction | 2013 |
| TWC Pro Ltd | Education | 2025 |
| Twelve Delta Limited | Information & communication | 2013 |
| Twenty Fifth Signature Limited | Wholesale & retail | 2023 |
| Twenty Three a Ltd | Real estate | 2025 |
| TWENTY20 Development Managers LLP | | 2023 |
| TWF Air Conditioning Services Ltd | Energy | 2015 |
| TWG Investment Manager LLP | | 2012 |
| Twickenham Pizza Enterprises Limited | Hospitality | 2025 |
| Twin Forks Ltd | Wholesale & retail | 2026 |
| Twin Technology Limited | Wholesale & retail | 2006 |