| TRTC23 Limited | Administrative & support | 1997 |
| Truckcare (NW) Limited | Wholesale & retail | 2007 |
| True Care 247 UK Limited | Administrative & support | 2023 |
| True Path Group Ltd | Information & communication | 2025 |
| True Property Holdings Ltd | Real estate | 2018 |
| Truestep Fitting Ltd | Construction | 2025 |
| Truestone Africa Limited | Administrative & support | 2015 |
| Truestone ARK Limited | Administrative & support | 2015 |
| Truestone Glenapp Castle Limited | Administrative & support | 2015 |
| Truestone Impact Consulting Limited | Administrative & support | 2015 |
| Truestone Impact Fund LP | | 2013 |
| Truestone Impact Investment Management Limited | Administrative & support | 2010 |
| Truestone Kemin Limited | Administrative & support | 2018 |
| Truestone KGS Limited | Administrative & support | 2014 |
| Trusted Computing Ltd | Information & communication | 2016 |
| Trusted Home Eyecare Ltd | Health & social care | 2022 |
| Trusttech Services Limited | Information & communication | 2024 |
| Trutfield Properties Limited | Real estate | 2000 |
| Truvi Holdings Limited | Information & communication | 2017 |
| Truvi Technologies Limited | Information & communication | 2019 |
| TRW Catering Ltd | Hospitality | 2025 |
| TS Cleveleys Ltd | Real estate | 2020 |
| TS Grainger Street Ltd | Construction | 2024 |
| TS Property Limited | Real estate | 2017 |
| TS R1 Ltd | Construction | 2024 |
| TSE168 Limited | Hospitality | 2026 |
| Tsim Tsum Ltd | Professional & scientific | 2014 |
| TSL Fire Safety Engineering Limited | Construction | 2014 |
| TSL Group Northwest Limited | Professional & scientific | 2002 |
| Tsompani Legal Limited | Professional & scientific | 2026 |
| Tsunami Limited | Financial services | 2019 |
| TSZ Content Ltd | Administrative & support | 2019 |
| TSZ Data Services Ltd | Professional & scientific | 2015 |
| TSZ Holdings Ltd | Financial services | 2019 |
| TT Landlord Limited | Real estate | 2020 |
| Ttdo Ltd | Professional & scientific | 2025 |
| TTH Football Consultancy Ltd | Professional & scientific | 2024 |
| TU Auditing Limited | Administrative & support | 2018 |
| Tucker Gardner Residential Limited | Professional & scientific | 2005 |
| Tudor Sourcing Limited | Wholesale & retail | 2025 |
| Tudorknight Limited | Wholesale & retail | 2013 |
| Tudorwin Ltd | Real estate | 2007 |
| Tuhee Ltd | Financial services | 2019 |
| Tuition Edge Limited | Education | 2025 |
| Tuktuk (UK) Limited | Wholesale & retail | 2014 |
| Tumbleriver Limited | Administrative & support | 2005 |
| Tunesoftware Limited | Administrative & support | 2014 |
| Tuple Cloud Limited | Professional & scientific | 2022 |
| Turbotech Precision Products Limited | Manufacturing | 1987 |
| Turinghub Limited | Information & communication | 2024 |
| Turner Performance Engineering Limited | Professional & scientific | 2025 |
| Turtle Consulting Limited | Professional & scientific | 2023 |
| Tusk Dental Ltd | Health & social care | 2025 |
| Tussock Limited | Professional & scientific | 2025 |
| Tutbury Castle Trading Limited | Arts & recreation | 2017 |
| Tvlc 15 Limited | Professional & scientific | 2022 |
| TW Integration Limited | Professional & scientific | 2023 |
| Twelve Misls Worldwide Oilfield Services Limited | Professional & scientific | 2001 |
| Twenty 15 Capital Limited | Wholesale & retail | 2022 |
| Twenty 15 Properties Ltd | Real estate | 2025 |
| Twentytwo Talent Ltd | Administrative & support | 2025 |
| Twice SHY LLP | | 2026 |
| Twig UK Holdco Limited | Financial services | 2021 |
| Twinfin Limited | Wholesale & retail | 2006 |
| Twinmind Limited | Information & communication | 2025 |
| Twique Ltd | Health & social care | 2022 |
| Twist Property (Spain) Limited | Real estate | 2014 |
| Two Bears Bakery Ltd | Wholesale & retail | 2021 |
| Two Bears Property Ltd | Real estate | 2021 |
| Two Flamingos Ltd | Information & communication | 2018 |
| Two Trees Management Company (Ambleside) Limited | Hospitality | 2016 |
| Two Wolves Properties Ltd | Real estate | 2014 |
| Twokai Limited | Professional & scientific | 2020 |
| Twpc Holdco Limited | Energy | 2010 |
| TY Glyn Residents Association Limited | Professional & scientific | 2009 |
| Typhoon Aircraft Management Limited | Transport & logistics | 2011 |
| Tyrell Corporation Limited | Professional & scientific | 2017 |
| U Drain Limited | Health & social care | 2009 |
| U-Chem Private Limited | Wholesale & retail | 2012 |
| U-Train Ltd | Education | 2021 |
| U-Train.Online Ltd | Wholesale & retail | 2023 |
| U.Mansur Ltd | Health & social care | 2021 |
| U2 Systems Limited | Professional & scientific | 2019 |
| U3 Consulting Limited | Professional & scientific | 2023 |
| UA Consultancy Services Limited | Administrative & support | 2021 |
| UA Property SPV Ltd | Real estate | 2025 |
| UBA Siddiqui Limited | Health & social care | 2020 |
| Ubara Limited | Professional & scientific | 2024 |
| UCS Corporate Solutions Ltd | Professional & scientific | 2006 |
| Uctal Ltd | Professional & scientific | 2000 |
| UFP Life Limited | Arts & recreation | 2018 |
| Uiym TEK Ltd | Information & communication | 2016 |
| UK & Ireland Risk Management Limited | Financial services | 2024 |
| UK a M Tech Ltd | Other services | 2021 |
| UK Air Management Limited | Professional & scientific | 1999 |
| UK Bandwidth Limited | Information & communication | 2018 |
| UK Boxer Midco 2 Limited | Professional & scientific | 2008 |
| UK Business Brands Limited | Professional & scientific | 2025 |
| UK Car Charge Ltd | Wholesale & retail | 2020 |
| UK Care Group Limited | Health & social care | 2026 |