| TSJ Capital Limited | Financial services | 2023 |
| TSK London Limited | Real estate | 2018 |
| Tssr Properties Limited | Real estate | 2016 |
| TT Nursery Limited | Education | 2024 |
| TT Realty Ltd | Real estate | 2024 |
| Ttdsa Limited | Wholesale & retail | 2026 |
| Ttike Limited | Financial services | 2022 |
| Ttselwynco Ltd | Financial services | 2023 |
| TTT Management Ltd | Administrative & support | 2024 |
| TUC Plastering Ltd | Construction | 2021 |
| Tudor Consultants Limited | Professional & scientific | 2012 |
| Tudor Lodge Consultants Limited | Real estate | 2004 |
| Tudor Porcelain Limited | Wholesale & retail | 2015 |
| Tuffty P Limited | Real estate | 2015 |
| Tulse Hill Properties Limited | Real estate | 2025 |
| Tulsi Properties Limited | Real estate | 2012 |
| Tune in Limited | Professional & scientific | 2022 |
| Turaboglu Ltd | Wholesale & retail | 2024 |
| Turning Point Aesthetics Ltd | Other services | 2023 |
| Turnover Films Ltd | Information & communication | 2016 |
| Turnt Properties Ltd | Real estate | 2025 |
| TW Holdings & Investments Limited | Financial services | 2012 |
| Twenty First Century Solutions Ltd | Professional & scientific | 2022 |
| Twiga Property Services Limited | Administrative & support | 2021 |
| Twinforce Holdings Limited | Financial services | 2023 |
| Twink Media Limited | Professional & scientific | 2025 |
| Twisted Design & Print Limited | Manufacturing | 2010 |
| Twisty Tails Nursery (Grand Union Alperton) Ltd | Education | 2019 |
| Twisty Tails Nursery (Pinner) Ltd | Health & social care | 2016 |
| Twisty Tails Nursery (Stanmore) Ltd | Health & social care | 2021 |
| Twisty Tails Nursery Limited | Education | 2009 |
| Two Lion Ventures Ltd | Information & communication | 2021 |
| Two Matrix Ltd | Information & communication | 2026 |
| Two Parr Ltd | Financial services | 2023 |
| Two Tower Optics Limited | Administrative & support | 1998 |
| Two Tower Properties Limited | Real estate | 2009 |
| Twofiveone Ltd | Information & communication | 2010 |
| Twomey Farriers Limited | Agriculture & fishing | 2018 |
| Twomey Waste Management Limited | Water & waste | 2004 |
| Tyfame Limited | Extraterritorial | 2012 |
| Tyneside and Teeside Developments Ltd. | Construction | 1992 |
| Tyre Check UK Ltd | Wholesale & retail | 2018 |
| Tzolag Ltd | Construction | 2025 |
| U & V Construction Limited | Construction | 2024 |
| U G I LLP | | 2017 |
| U H Advisory Limited | Real estate | 2023 |
| U.D.C. Wholesale Ltd | Transport & logistics | 2018 |
| UB1 Construction Services Ltd | Construction | 2020 |
| Ubicom Limited | Information & communication | 2012 |
| Ubongo Ltd | Professional & scientific | 2016 |
| UGO Silicon Ltd | Construction | 2025 |
| UK 5 Star Ltd | Wholesale & retail | 2024 |
| UK Automotive Group Ltd | Wholesale & retail | 2026 |
| UK Business Resource Centre Limited | Administrative & support | 2021 |
| UK Cloud Accountants Limited | Professional & scientific | 2017 |
| UK Digital Media Consultants Limited | Wholesale & retail | 2017 |
| UK Express Claims Ltd | Other services | 2015 |
| UK Influence Limited | Real estate | 2005 |
| UK Kold Ltd | Construction | 2015 |
| UK Medisource Ltd | Information & communication | 2016 |
| UK Oyster Trading Limited | Wholesale & retail | 2013 |
| UK Savers Ltd | Wholesale & retail | 2025 |
| UK Specialist Care Ltd | Health & social care | 2019 |
| UK Steel Fabricators & Stock Holders Ltd | Construction | 2021 |
| UK Welltech Limited | Financial services | 2021 |
| UK WIN - Doors & Conservatories Ltd | Construction | 2026 |
| UKI Capital Investments Ltd | Other services | 2016 |
| UKI Invest Ltd | Extraterritorial | 2012 |
| UKI Limited | Other services | 1997 |
| UKI Pharma and Medical Devices Limited | Wholesale & retail | 2024 |
| UKI Systems Ltd | Administrative & support | 2007 |
| UKN International Ltd | Wholesale & retail | 2023 |
| UKS Buildings Limited | Real estate | 2024 |
| Ukthriftarena Ltd | Wholesale & retail | 2024 |
| Ultimate Insight Consultants Ltd | Information & communication | 2025 |
| Ultimate Insight Limited | Administrative & support | 2012 |
| Ultimate T Limited | Wholesale & retail | 2014 |
| Ulus Properties Limited | Real estate | 2012 |
| Umaar Developments Ltd | Construction | 2025 |
| Umai Sushi Surrito Ltd | Hospitality | 2025 |
| Umal ALI Ltd | Professional & scientific | 2022 |
| Umbra Marketing Ltd | Professional & scientific | 2026 |
| Umer & Rida LLP | | 2018 |
| Uneek Creative Group Ltd | Administrative & support | 2025 |
| UNI Halls Ltd | Real estate | 2025 |
| Unibanque SA Ltd | Financial services | 2019 |
| Unic-Uk Ltd | Wholesale & retail | 2017 |
| Unicon Pharma Ltd | Administrative & support | 2025 |
| Unicorn Pharmaceuticals Limited | Other services | 2023 |
| Unidosh Ltd. | Information & communication | 2015 |
| Unify Design & Build Limited | Construction | 2020 |
| Unimpossible Limited | Professional & scientific | 2010 |
| Unique Intervention Limited | Administrative & support | 2017 |
| Unit 44 (London) Ltd | Administrative & support | 2023 |
| United Ecom Solutions Ltd | Wholesale & retail | 2026 |
| Unity Crew Ltd | Hospitality | 2026 |
| Universal Finance Consulting Ltd | Financial services | 2023 |
| Universal Home & Healthcare Training Ltd | Transport & logistics | 2023 |
| Universal Investments & Developments Limited | Construction | 2014 |
| Universal Mastercrafts Limited | Wholesale & retail | 2014 |