| TRI Consulting Inc Limited | Professional & scientific | 2013 |
| TRI Flames Kitchen Limited | Hospitality | 2026 |
| TRI Leisure Limited | Professional & scientific | 2015 |
| TRI Nine Ltd | Administrative & support | 2023 |
| Tri-Squared Ltd | Health & social care | 2018 |
| Triangle Pensions Limited | Administrative & support | 2010 |
| Tribe Contemporary Rugs Limited | Wholesale & retail | 2004 |
| TRIBE7 (UK) Limited | Professional & scientific | 2024 |
| Tricel Ltd | Information & communication | 2025 |
| Tricom Properties Ltd | Real estate | 2020 |
| Trident Cranes Ltd | Administrative & support | 2022 |
| Trident Holdings London Limited | Professional & scientific | 2023 |
| Trident House RTM Company Limited | Households | 2026 |
| Trident Kitchen Limited | Hospitality | 2020 |
| Trident Lifting Solutions Ltd | Administrative & support | 2016 |
| Trident Luxury Ltd | Wholesale & retail | 2024 |
| Trident Transformation Limited | Information & communication | 2018 |
| Triedent Properties CIC | Hospitality | 2023 |
| Trifan Civils Limited | Construction | 2022 |
| Trifolium Property LLP | | 2024 |
| Trigonometry Ltd. | Administrative & support | 2020 |
| Trigot Limited | Administrative & support | 2004 |
| Triilok Limited | Wholesale & retail | 2024 |
| Trikona Consultants Limited | Professional & scientific | 2006 |
| Trimdon Northwest Ltd | Real estate | 2024 |
| Trimrose (LDN) Limited | Construction | 2015 |
| Trina Software Limited | Information & communication | 2014 |
| Trinetr Limited | Information & communication | 2026 |
| Trinfinity Ltd | Administrative & support | 2023 |
| Tring Limited | Real estate | 2014 |
| Trinity (Grays) Limited | Real estate | 2007 |
| Trinity Alliance Ltd | Other services | 2020 |
| Trinity AZ Ltd | Real estate | 2024 |
| Trinity Company (LON) Limited | Financial services | 2012 |
| Trinity Crabwall Limited | Hospitality | 2017 |
| Trinity Food Limited | Other services | 2012 |
| Trinity Global Advisors Ltd | Financial services | 2024 |
| Trinity Maintenance Ltd | Wholesale & retail | 2025 |
| Trinity Services Group Limited | Administrative & support | 2014 |
| Trinity Spray Plasterer and Drylining Ltd | Construction | 2018 |
| Trinity Square RTM Company Ltd | Households | 2025 |
| Trinity Supported Living Ltd | Health & social care | 2023 |
| Trinity Wood Limited | Real estate | 2017 |
| Trinnitech U.K. PVT. Ltd. | Mining & quarrying | 2017 |
| Trio Pharm Ltd | Health & social care | 2022 |
| Trio Reloaded Ltd | Wholesale & retail | 2022 |
| Triogue Limited | Professional & scientific | 2018 |
| Trioport Limited | Professional & scientific | 1987 |
| Tripacirfa Ltd | Administrative & support | 2026 |
| Triple GEM Limited | Other services | 2019 |
| Triple I Ltd | Transport & logistics | 2024 |
| Triple Loop Development Ltd | Professional & scientific | 2022 |
| Triple Moon Properties Limited | Real estate | 2023 |
| Triple One SIX Ltd | Other services | 2023 |
| Triple S Caterers Limited | Hospitality | 2015 |
| Triple S Foods Limited | Manufacturing | 2017 |
| Triple Seven Real Estate Investments Ltd | Real estate | 2020 |
| Triplealuxuryessentials Ltd | Wholesale & retail | 2026 |
| Tripleforce Security Limited | Administrative & support | 2008 |
| Tripmart International Limited | Administrative & support | 2009 |
| Tripod Survey Limited | Construction | 2017 |
| Tripple R and R Team Limited | Real estate | 2024 |
| Triptonic Limited | Administrative & support | 2025 |
| Triptych Productions Limited | Information & communication | 2007 |
| Trisara Limited | Wholesale & retail | 2025 |
| Trisha C. Design Limited | Manufacturing | 2019 |
| Trisk Associates Ltd | Real estate | 2011 |
| Tristar 2 Wealth Limited | Real estate | 2016 |
| Tristar Wealth Limited | Real estate | 2015 |
| Tristone Property Group Ltd | Real estate | 2025 |
| Trisul Ltd | Wholesale & retail | 2026 |
| Tritone Technology Limited | Wholesale & retail | 2023 |
| Triumph UK Limited | Professional & scientific | 2021 |
| Triumph Waterfield Ltd. | Extraterritorial | 1998 |
| Triveda Limited | Health & social care | 2009 |
| Trivedi Business Solutions Limited | Hospitality | 2007 |
| Trivedi Enterprise Ltd | Wholesale & retail | 2021 |
| Trivedi Estates Ltd | Real estate | 2025 |
| Triven Capital Ltd | Professional & scientific | 2025 |
| Trivexa Consulting Ltd | Information & communication | 2025 |
| Trizinga Ltd | Wholesale & retail | 2015 |
| TRK Commercial Ltd | Financial services | 2024 |
| Trogal Griffin Associates Limited | Professional & scientific | 2011 |
| Troika Technologies Limited | Information & communication | 2009 |
| Trois Invest Limited | Professional & scientific | 2020 |
| Troochek Apps Limited | Information & communication | 2021 |
| Trop Fruit & VEG Limited | Wholesale & retail | 2025 |
| Tropix Limited | Hospitality | 2018 |
| Trostify Ltd | Financial services | 2016 |
| Trovenafoods Ltd | Wholesale & retail | 2026 |
| Trowsa Plant (2014) Limited | Administrative & support | 2010 |
| Troy Assets Ltd | Real estate | 2022 |
| TRP Builders Ltd | Construction | 2023 |
| TRP Training Limited | Education | 2011 |
| TRP23 Limited | Hospitality | 2023 |
| Trsi K Ltd | Wholesale & retail | 2013 |
| Truckfoodlondon Ltd | Hospitality | 2023 |
| True Finish Ltd | Construction | 2025 |
| True Mind Consulting Limited | Health & social care | 2023 |
| True North Accounting Ltd | Professional & scientific | 2024 |