| Tracsapp Limited | Information & communication | 2020 |
| Tractland Property Management Limited | Real estate | 1983 |
| Trade MAX UK Limited | Administrative & support | 2000 |
| Trade Metals Recycling (London) Limited | Administrative & support | 2018 |
| Trade to the Crowd Ltd | Hospitality | 2019 |
| Tradeedge One Ltd | Financial services | 2025 |
| Tradelux Holdings Limited | Extraterritorial | 2017 |
| Trading Sites Limited | Administrative & support | 2003 |
| Tradingdale Limited | Real estate | 1977 |
| Trafalgar Yachts Limited | Manufacturing | 2026 |
| Trafford Securities Limited | Construction | 1953 |
| Trailblazing Ltd | Information & communication | 2006 |
| Trailblazing Properties LLP | | 2022 |
| Trailertek Limited | Wholesale & retail | 1989 |
| Train Equus Limited | Administrative & support | 2005 |
| Train Your Mind Ltd | Other services | 2017 |
| Traknova Ltd | Information & communication | 2025 |
| Transform and Perform Ltd | Professional & scientific | 2010 |
| Transforming Solutions Ltd | Information & communication | 2024 |
| Trantham and SON Ltd | Households | 2018 |
| Trashy Bags Africa Limited | Manufacturing | 2021 |
| Travel Saas Limited | Information & communication | 2021 |
| Trax International Ltd | Professional & scientific | 2015 |
| TRC Plumbing & Heating Ltd | Construction | 2014 |
| Treadmark Tyres Limited | Extraterritorial | 2008 |
| Treasury Court Freehold Limited | Households | 2025 |
| Tree Creative Ltd | Hospitality | 2025 |
| Tree Style (UK) Limited | Administrative & support | 2014 |
| Tree Style Ltd | Administrative & support | 2020 |
| Treverva Limited | Hospitality | 2016 |
| Tri-Style Investments Limited | Real estate | 1973 |
| Tribal Elders Limited | Professional & scientific | 1993 |
| Trigenit Holdings Limited | Professional & scientific | 2016 |
| Trinarysecure Limited | Information & communication | 2008 |
| Trine Miller Limited | Professional & scientific | 2018 |
| Trinity Air Charter Limited | Transport & logistics | 2017 |
| Trinity Grain Marketing Limited | Wholesale & retail | 2024 |
| Trinity Grain Transport Limited | Transport & logistics | 2011 |
| Trinity Lifts Ltd | Manufacturing | 2016 |
| Trinity Winchester | Hospitality | 1999 |
| Trinity Winchester Supported Housing Limited | Construction | 2018 |
| TRINITY3 Limited | Information & communication | 2024 |
| Trinley Farming Limited | Professional & scientific | 2005 |
| Trioss Limited | Professional & scientific | 2012 |
| Triptold Ltd | Information & communication | 2025 |
| Trolls and Tribulations Ltd | Manufacturing | 2009 |
| Trooper Leisure Limited | Hospitality | 2020 |
| Trosemaryn Ltd | Hospitality | 2025 |
| True Group Agency Ltd | Professional & scientific | 2020 |
| Trueswift Limited | Information & communication | 2010 |
| Trustgate Limited | Construction | 2020 |
| Trustjennings Limited | Other services | 2024 |
| Trustnoted International Limited | Information & communication | 2026 |
| TS Orangery Ltd | Hospitality | 2023 |
| TS Plumbing and Heating Services Ltd | Construction | 2019 |
| TSC (the Sameday Company) Limited | Transport & logistics | 2003 |
| TSM Projects Limited | Construction | 2020 |
| TSU Professional Services Ltd | Professional & scientific | 2024 |
| Tube MAP Limited | Wholesale & retail | 2013 |
| Tuff Tents Ltd | Professional & scientific | 2025 |
| Turbo-K Limited | Wholesale & retail | 1998 |
| Turkish Style Barber One Ltd | Other services | 2019 |
| Turn the Slate Productions Limited | Information & communication | 2011 |
| Turn UP Your Volume Ltd | Information & communication | 1998 |
| Turning Leaves Limited | Administrative & support | 2002 |
| Turomar Limited | Transport & logistics | 2020 |
| Turopot Limited | Transport & logistics | 1978 |
| Turquoise Water Limited | Extraterritorial | 2025 |
| Turrall Group Ltd | Financial services | 2025 |
| Tutors on Global Ltd | Education | 2026 |
| Tutt-Leppard Property Management Limited | Real estate | 2016 |
| TV Associates Limited | Administrative & support | 2015 |
| TVD Driveways Ltd | Construction | 2026 |
| TW Ocean Ltd | Professional & scientific | 2026 |
| TW Studio Ltd | Professional & scientific | 2020 |
| TW Tyres Autocentre Limited | Extraterritorial | 2011 |
| TWC Digital Ltd | Extraterritorial | 2022 |
| Twenty SIX and Eight Limited | Hospitality | 2025 |
| Twilight Trees Ltd | Wholesale & retail | 2014 |
| Twilik Ltd | Information & communication | 2020 |
| Twisted Rentals Limited | Real estate | 2021 |
| Two Hands Winchester Limited | Hospitality | 2024 |
| Twyford Community Centre CIC | Arts & recreation | 2021 |
| Twyford Heritage Limited | Professional & scientific | 2011 |
| Twyford Itchen Watermeadow Limited | Agriculture & fishing | 2004 |
| Twyford Playgroup | Education | 2012 |
| Twyford Valley Conservation C.I.C. | Arts & recreation | 2022 |
| Ty-Tanium Piercings Ltd | Other services | 2025 |
| Tyne Land Profits Ltd | Real estate | 2024 |
| Tyremark Limited | Extraterritorial | 1996 |
| Tytherington Down LLP | | 2011 |
| U Developments Ltd | Construction | 2017 |
| UD Invest Limited | Construction | 2019 |
| UDN Redevelopments Ltd | Real estate | 2016 |
| UK Country Estates Limited | Agriculture & fishing | 2012 |
| UK Film Trustee Company Limited | Information & communication | 2010 |
| UK Health Insourcing Ltd | Health & social care | 2020 |
| UK Sanitising Solutions Ltd | Administrative & support | 2020 |
| Ukie Education Ltd | Education | 2025 |
| Ultimate Building Services Ltd | Construction | 2008 |