| Tradexa Ltd | Wholesale & retail | 2026 |
| Trading Post (the Galleria) Limited | Hospitality | 1991 |
| Trading Seven Limited | Hospitality | 2022 |
| Trading Signals Direct Ltd | Information & communication | 2015 |
| Traffco Accounting Ltd | Professional & scientific | 2017 |
| Traffco Construction Services Limited | Construction | 2024 |
| Trail Reverie Limited | Information & communication | 2023 |
| Trailer World Ltd | Wholesale & retail | 2016 |
| Trails and Tales Limited | Administrative & support | 2025 |
| Train Door Solutions Ltd | Manufacturing | 2019 |
| Traineasy Ltd | Information & communication | 2000 |
| Trainer Space Ltd | Arts & recreation | 2025 |
| Traintrack Solutions Limited | Information & communication | 2024 |
| Trajan Scientific Europe Ltd | Wholesale & retail | 1968 |
| Tralys Ltd | Financial services | 2021 |
| Tran's Property Investment Limited | Real estate | 2018 |
| Tranquille Care Limited | Health & social care | 2024 |
| Trans Assist Limited | Information & communication | 2015 |
| Trans Demha Limited | Transport & logistics | 2018 |
| Trans MS Ltd | Construction | 2021 |
| Trans-Siberian Gold Limited | Mining & quarrying | 1972 |
| Transatlantica Partners (UK) Limited | Professional & scientific | 2019 |
| Transcend Awards Holdings Limited | Financial services | 2022 |
| Transcend Awards Limited | Administrative & support | 2017 |
| Transcend Movement Limited | Other services | 2016 |
| Transcendere Ltd | Professional & scientific | 2011 |
| Transcim Limited | Information & communication | 2025 |
| Transcosmos Information Systems Group Limited | Professional & scientific | 1991 |
| Transcosmos Information Systems Limited | Information & communication | 2000 |
| Transdac Limited | Transport & logistics | 2024 |
| Transeb Limited | Transport & logistics | 2013 |
| Transfer of Malice Ltd | Wholesale & retail | 2025 |
| Transform Trade Ltd | Extraterritorial | 2019 |
| Transform With Venus Ltd | Wholesale & retail | 2025 |
| Transformation Business Mentoring Ltd | Professional & scientific | 2026 |
| Transformational Accounting Ltd | Professional & scientific | 2024 |
| Transglobe Solution Limited | Information & communication | 2014 |
| Transines Ltd | Transport & logistics | 2026 |
| Transit Ease Ltd | Administrative & support | 2025 |
| Transit Networks Ltd | Information & communication | 2011 |
| Transition UK Limited | Education | 2003 |
| Translators' Guild (1986) Limited(The) | Other services | 1986 |
| Transmirea Ltd | Transport & logistics | 2018 |
| Transnet Fast Ltd | Other services | 2019 |
| Transpluse Ltd | Transport & logistics | 2024 |
| Transport & Asset Rentals Limited | Transport & logistics | 2025 |
| Transport Eric.Ro Limited | Transport & logistics | 2025 |
| Transport for Milton Keynes Ltd | Transport & logistics | 2025 |
| Transport LMA Ltd | Transport & logistics | 2024 |
| Transport Parcel Ltd | Transport & logistics | 2024 |
| Transport Solutions Consultancy Ltd | Real estate | 2000 |
| Transport Technical Innovation Ltd | Manufacturing | 2023 |
| Transport@Future Ltd | Transport & logistics | 2022 |
| Transporter MK Limited | Transport & logistics | 2020 |
| Transrobert Limited | Transport & logistics | 2019 |
| Transted Limited | Professional & scientific | 1995 |
| Transvend Limited | Manufacturing | 2003 |
| Trappin Tracksuits Ltd | Wholesale & retail | 2025 |
| Travailers Adullam CIC | Education | 2025 |
| Travel Frontiers Limited | Administrative & support | 2016 |
| Travel Portals Ltd | Wholesale & retail | 2019 |
| Travel With Esther Ltd | Administrative & support | 2024 |
| Travelling Light Productions Limited | Information & communication | 2018 |
| Traydee Limited | Wholesale & retail | 2024 |
| TRB Solutions Group Ltd | Other services | 2024 |
| TRC Limited | Professional & scientific | 2004 |
| Trdr Limited | Financial services | 2020 |
| Tread Right MK 24/7 Ltd | Wholesale & retail | 2025 |
| Treat ST Limited | Hospitality | 2019 |
| Treat Street Ltd | Hospitality | 2013 |
| Treatsbygigi Ltd | Wholesale & retail | 2024 |
| Trebla Civils Ltd | Construction | 2014 |
| Trebo Resources Limited | Information & communication | 2025 |
| Trec Digital Ltd | Professional & scientific | 2022 |
| Trecek Ltd | Transport & logistics | 2021 |
| Treeple M Realty Ltd | Real estate | 2025 |
| Trek Bicycle Corporation Limited | Wholesale & retail | 1989 |
| Trembath Ltd | Professional & scientific | 2023 |
| Trend Consulting and Advisory Services Ltd | Information & communication | 2025 |
| Trend Estates Ltd | Real estate | 2025 |
| Trend Property & Maintenance Ltd | Construction | 2024 |
| Trend Residential Ltd | Real estate | 2026 |
| Trendcraft Investment Ltd | Financial services | 2019 |
| Trendicart Ltd | Wholesale & retail | 2025 |
| Trendrevel Services Limited | Professional & scientific | 1993 |
| Trends Trading Ltd | Wholesale & retail | 2025 |
| Trendsignal Limited | Information & communication | 2003 |
| Trendy Services Limited | Health & social care | 2015 |
| Trent Restaurants Ltd | Hospitality | 2024 |
| Trenzco Mercator Ltd | Wholesale & retail | 2026 |
| Trescuda Recruitment Group Ltd | Administrative & support | 2017 |
| Tresleigh, Mevigissy Limited | Hospitality | 2019 |
| Trevor J. Stimpson Limited | Extraterritorial | 1984 |
| Trew Fire and Secuity Ltd | Administrative & support | 2022 |
| Trexso Ltd | Wholesale & retail | 2026 |
| TRI Retail Limited | Hospitality | 2022 |
| Tria Coffee Ltd | Hospitality | 2025 |
| Triadic Consultancy Limited | Information & communication | 2017 |
| Triadic Groups Ltd | Real estate | 2021 |
| Triark Protective Ltd | Wholesale & retail | 2025 |