| Triopen Water Limited | Education | 2020 |
| Triopenwater Swim LAB Ltd | Education | 2026 |
| Triple J Housing Ltd | Real estate | 2025 |
| Triple P & E Insulation Services Ltd | Manufacturing | 2018 |
| Triple S Limited | Administrative & support | 2025 |
| Triple Tree Limited | Health & social care | 2025 |
| Triplebell Entertainment Ltd | Information & communication | 2023 |
| Tripod Electrical Ltd | Extraterritorial | 2025 |
| TRM Tax & Bookkeeping Services Ltd | Professional & scientific | 2019 |
| Tru-Line (Suspended Ceilings) Limited | Construction | 1990 |
| Tru:Vai Limited | Hospitality | 2017 |
| Truce Education Limited | Education | 2026 |
| Truck & Spares Ltd | Wholesale & retail | 2025 |
| Truck & Van Limited | Wholesale & retail | 2020 |
| Truck Tech (NE) Limited | Wholesale & retail | 2006 |
| Truckfix (N E) Limited | Wholesale & retail | 2012 |
| True North Cleaning Services Ltd | Administrative & support | 2026 |
| Trunk Road Budget Cars Ltd | Wholesale & retail | 2020 |
| Trusflo Design Ltd | Professional & scientific | 2019 |
| TS Auto Repair (NE) Ltd | Wholesale & retail | 2023 |
| TS Commercial Solutions Ltd | Wholesale & retail | 2024 |
| TS Communications Ltd | Construction | 2024 |
| TS Plumbing & Bathrooms Ltd | Construction | 2025 |
| TS Plumbing & Heating (NE) Ltd | Construction | 2023 |
| TS1 Salon Ltd | Other services | 2026 |
| TS3 Barbers Limited | Other services | 2025 |
| TS3 Sports Limited | Wholesale & retail | 2017 |
| TS3 Storage Ltd | Administrative & support | 2026 |
| TS3 Tandoori Ltd | Hospitality | 2020 |
| TS5 Barber Ltd | Other services | 2024 |
| TS5 Travel Ltd | Transport & logistics | 2025 |
| TS88 Engineering Services Ltd | Construction | 2018 |
| TSA Solutions Ltd | Construction | 2023 |
| TSG Technical Limited | Professional & scientific | 2018 |
| TSL Energy Ltd | Wholesale & retail | 2020 |
| TT Firesafe Ltd | Other services | 2019 |
| TT Firesafe Solutions Ltd | Construction | 2024 |
| TT Industrial Hire Ltd | Construction | 2019 |
| TT Industrial Ltd | Construction | 2003 |
| TT Luxury Ltd | Wholesale & retail | 2020 |
| TT2SOLUTIONS Limited | Information & communication | 2025 |
| Ttagz Ltd | Information & communication | 2021 |
| TTE Apprenticeships Limited | Education | 2009 |
| TTE International Limited | Education | 2001 |
| TTE Technical (UK) Ltd. | Education | 2010 |
| TTI Trading Limited | Wholesale & retail | 2025 |
| TTS Engineering Ltd | Manufacturing | 2005 |
| TU Enterprise and Innovation Limited | Information & communication | 2021 |
| TU London Limited | Education | 2022 |
| TU Online Limited | Education | 2019 |
| Tukkhana Ltd | Hospitality | 2025 |
| Tulip's 2000 Ltd | Hospitality | 2026 |
| Tupudha Builds Ltd | Construction | 2026 |
| Turkish Barber Marton Ltd | Other services | 2024 |
| Turkish Food Hub Ltd | Hospitality | 2025 |
| Turner Commercial Services Limited | Professional & scientific | 2023 |
| Tutorworks Ltd | Education | 2019 |
| TVR (UK) Ltd | Administrative & support | 2011 |
| TVR Radio Limited | Information & communication | 2024 |
| TVS Services Limited | Other services | 2018 |
| Tvvg Ltd | Real estate | 2020 |
| TVW Streaming Ltd | Wholesale & retail | 2025 |
| TW Property Group Ltd | Financial services | 2022 |
| TW PUB Management Ltd | Professional & scientific | 2010 |
| TW Search Solutions Limited | Water & waste | 2024 |
| Twana NE Limited | Real estate | 2024 |
| Twelve Yards Management Group Ltd | Professional & scientific | 2023 |
| Twelvesides Technologies Ltd | Information & communication | 2025 |
| Twenty Eleven Limited | Real estate | 2018 |
| Twenty Seven Live Ltd | Arts & recreation | 2015 |
| TWENTY9 Cycling Limited | Arts & recreation | 2026 |
| Twiggy's Childcare Ltd | Health & social care | 2026 |
| Twin Moore Ltd | Wholesale & retail | 2025 |
| Twin Pearl Consulting Ltd | Information & communication | 2026 |
| Twin Treats Ltd | Hospitality | 2025 |
| TWM Motorsport Ltd | Transport & logistics | 2018 |
| TWM Safety Ltd | Professional & scientific | 2026 |
| Twndt Ltd | Professional & scientific | 2024 |
| Two Little Pigs PUB Co Limited | Hospitality | 2016 |
| Two Moons Nunthorpe Ltd | Other services | 2025 |
| Twos Corporation Ltd | Professional & scientific | 2023 |
| Typg Ltd | Real estate | 2025 |
| Tyre Club Glasgow Ltd | Wholesale & retail | 2026 |
| Tyrus Limited | Information & communication | 2010 |
| Tytler Rigging Ltd | Construction | 2025 |
| U C S (NE) Ltd | Wholesale & retail | 2014 |
| U Choose U Lease Catering Equipment Limited | Wholesale & retail | 2017 |
| U Hire Limited | Administrative & support | 2008 |
| U Save Wholesalers Ltd | Wholesale & retail | 2023 |
| U&H Mens Haircut Ltd | Other services | 2024 |
| U.T.I. (UK) Limited | | 1978 |
| UAG Trend Hub Ltd | Wholesale & retail | 2026 |
| UB66 Ltd | Wholesale & retail | 2024 |
| Ubuntu Multicultural Centre CIC | Professional & scientific | 2020 |
| UCS Renewables Limited | Construction | 2010 |
| UDP (NE) Ltd | Manufacturing | 2024 |
| Ufologix Digital Solutions Ltd | Wholesale & retail | 2025 |
| Uggo Ltd | Transport & logistics | 2026 |
| UH Consultancy Ltd | Health & social care | 2023 |
| UK Autos & Cars Ltd | Wholesale & retail | 2025 |