| TRC Collectibles Ltd | Wholesale & retail | 2025 |
| Treetop REC Ltd | Administrative & support | 2021 |
| Treglos Residents Association Limited | Administrative & support | 1967 |
| Trenvale Limited | Construction | 1988 |
| Trevlin Landscapes Limited | Administrative & support | 2003 |
| Tribal Energy Ltd | Administrative & support | 2010 |
| Trident Voice and Data Limited | Information & communication | 2003 |
| Triff Consulting Limited | Professional & scientific | 2025 |
| Trigger Design Limited | Professional & scientific | 2007 |
| Trilby Limited | Real estate | 2005 |
| Trinity Close Chilworth Limited | Households | 2025 |
| Trinity Escapes Ltd | Hospitality | 2026 |
| Triple 8 Transport & Trade Ltd | Transport & logistics | 2025 |
| Triple H Design & Construction Limited | Construction | 2023 |
| Tripleaaa International Limited | Professional & scientific | 2024 |
| Triplex Capital Limited | Extraterritorial | 2008 |
| Tristmire Limited | Construction | 1995 |
| Tristmire SUB Limited | Construction | 2017 |
| Trojan Information Security Ltd | Information & communication | 2011 |
| Trojan Mining Ltd | Financial services | 2021 |
| Troy Digital UK Limited | Other services | 2017 |
| Trubrics Limited | Information & communication | 2022 |
| Trugym Ltd | Professional & scientific | 2013 |
| Trust Electronics Ltd | Wholesale & retail | 2020 |
| Ts-Movers Ltd | Transport & logistics | 2025 |
| TSM Copiers Limited | Administrative & support | 1997 |
| TTG Electronics Limited | Professional & scientific | 1936 |
| Tubbeo Ltd | Information & communication | 2013 |
| Tudor House Residents Association Limited | Households | 2004 |
| Tundra International Limited | Arts & recreation | 2019 |
| Tungsten Limited | Professional & scientific | 2016 |
| Turbo Acquisitions 10 Midco Limited | Financial services | 2019 |
| Turnaco Ltd | Professional & scientific | 2020 |
| Turner (London) Limited | Other services | 2006 |
| Turquoise Associates Limited | Extraterritorial | 2004 |
| Turquoise Capital LLP | | 2005 |
| Turquoise International Limited | Financial services | 2002 |
| Tutabase Ltd | Education | 2025 |
| TVM Management Co Ltd | Arts & recreation | 2017 |
| TVT 1978 Ltd | Transport & logistics | 2021 |
| Twenty Twenty Solutions Ltd | Professional & scientific | 2016 |
| Twenty Two Lifestyle Ltd | Administrative & support | 2025 |
| TWENTY3 Club Limited | Administrative & support | 2021 |
| Twinstacks Limited | Construction | 2006 |
| Two MAN Removals Limited | Transport & logistics | 2022 |
| Twobeds Limited | Hospitality | 2013 |
| Twotenofour Investments Limited | Health & social care | 2005 |
| TWP Accountants Limited | Professional & scientific | 2024 |
| TWP Accounting LLP | | 2007 |
| TWP Audit & Assurance Services Limited | Extraterritorial | 2008 |
| TWP Business Services Limited | Extraterritorial | 2008 |
| TWP Corporate Finance Limited | Extraterritorial | 2008 |
| TWP Insight Limited | Professional & scientific | 2019 |
| TWP Payroll Services Limited | Extraterritorial | 2008 |
| TWP Probate Limited | Extraterritorial | 2020 |
| TWP Profit Improvement Consultancy Limited | Extraterritorial | 2012 |
| TWP Tax Consulting Limited | Extraterritorial | 2008 |
| TWX Limited | Other services | 2017 |
| Tyburn Partners Limited | Professional & scientific | 2022 |
| Tylt Limited | Administrative & support | 2021 |
| Tyres 4 Less Limited | Wholesale & retail | 2003 |
| U.S Direct E-Commerce U.K. Limited | Wholesale & retail | 2018 |
| Uirtus Marine Services Limited | Administrative & support | 2018 |
| UK Flood Defence Systems Ltd | Water & waste | 2012 |
| UK Foam Away & Roofing Ltd | Construction | 2026 |
| UK Home Investments Limited | Real estate | 2017 |
| UK National Tech Ltd | Wholesale & retail | 2026 |
| UK Responsible Person Association | Other services | 2021 |
| Ukatco Ltd | Professional & scientific | 2009 |
| Ukiot Ltd | Wholesale & retail | 2018 |
| UMU Technology Services Limited | Construction | 2018 |
| Underground Graphics Ltd. | Professional & scientific | 2024 |
| Unending Work Ltd | Manufacturing | 2024 |
| Unibox Motorsport LLP | | 2013 |
| Uniclip Limited | Manufacturing | 1947 |
| Uniform Technology Limited | Information & communication | 2025 |
| Unigate Dairies Limited | Professional & scientific | 1941 |
| Unit Seven Fitness Ltd | Arts & recreation | 2025 |
| United Command International Ltd | Information & communication | 2009 |
| Unity Cloud Ltd | Information & communication | 2014 |
| University Vandals Limited | Arts & recreation | 2010 |
| UP Market Solutions Ltd | Professional & scientific | 2007 |
| Upex EOT Limited | Administrative & support | 2023 |
| Upex Group Ltd | Administrative & support | 2016 |
| Ups-Mikos Limited | Construction | 2021 |
| Urban Connextions Limited | Real estate | 2017 |
| Urban Design Studio Ltd | Professional & scientific | 2006 |
| Urban LDN Limited | Construction | 2018 |
| Urban Xchange Limited | Real estate | 2017 |
| Urrw Limited | Construction | 2013 |
| US Productions Ltd | Information & communication | 2022 |
| Usave Digital Ltd | Professional & scientific | 2017 |
| Uxgrid Limited | Information & communication | 2019 |
| V W Co. Limited | Extraterritorial | 1985 |
| V W Pressings Limited | Professional & scientific | 1980 |
| V&B Manufacturing Ltd | Professional & scientific | 2022 |
| Vaishaly Beauty Limited | Other services | 2020 |
| Valescourt Ltd | Information & communication | 1980 |
| Validscope Limited | Real estate | 1997 |
| Valkostar Limited | Administrative & support | 2023 |