| Transdanubia UK Ltd | Transport & logistics | 2008 |
| Transport Industry Driver Education Services Ltd | Transport & logistics | 2004 |
| Transport PG Ltd | Transport & logistics | 2012 |
| Travel Hounds Limited | Administrative & support | 2023 |
| Treatment Abroad Group Ltd | Professional & scientific | 2025 |
| Treaty Drains Ltd | Water & waste | 2021 |
| Treaty Groundwork Ltd | Construction | 2023 |
| Tree Perfect Ltd | Agriculture & fishing | 2025 |
| Treebrick Limited | Households | 2004 |
| Trellis Technology Solutions Ltd | Administrative & support | 2024 |
| Trend Creations Ltd | Manufacturing | 2009 |
| Trent Systems Limited | Administrative & support | 2018 |
| Trevera Property Management Limited | Households | 1994 |
| TRG Construction Management Ltd | Construction | 2018 |
| TRG Waste Ltd | Transport & logistics | 2023 |
| Triangle Family Assessment Ltd | Health & social care | 2023 |
| Triashous Limited | Health & social care | 2012 |
| Trinity SIX Capital Limited | Financial services | 2018 |
| Trinity Swift UK Limited | Wholesale & retail | 2017 |
| Triple H Maintenance Ltd | Construction | 2021 |
| Triple H Property Investment Ltd | Real estate | 2026 |
| Triquetra Trust Limited | Other services | 2011 |
| Trishul Global PVT Ltd | Wholesale & retail | 2025 |
| Triton Property Maintenance Ltd | Real estate | 2020 |
| TRS Advice Limited | Professional & scientific | 2012 |
| Truck Buyer Limited | Wholesale & retail | 2026 |
| Tstb Ltd | Professional & scientific | 2023 |
| TTS Metal Work Ltd | Manufacturing | 2026 |
| TTT Properties LLP | | 2016 |
| Tuck Inn Style Ltd | Other services | 2025 |
| Tudor Cross PRE School CIC | Education | 2009 |
| Tugcem Limited | Hospitality | 2025 |
| Tunc Properties YY Ltd | Real estate | 2025 |
| Turkcell Ltd | Extraterritorial | 2025 |
| Turkish Household (UK) Limited | Other services | 2013 |
| Turnbull Flooring Agency Ltd | Wholesale & retail | 2016 |
| Turnkey Building Contractors Ltd | Construction | 2019 |
| Turquoise London Ltd | Wholesale & retail | 2019 |
| Twenty Eight Properties & Management Ltd | Real estate | 2025 |
| Twisted Silver Creative Ltd | Information & communication | 2020 |
| TX BS1 Ltd | Hospitality | 2024 |
| TX CR01 Ltd | Hospitality | 2021 |
| TX EH1 Ltd | Hospitality | 2020 |
| TX G1 Ltd | Hospitality | 2024 |
| TX Hub Ltd | Hospitality | 2020 |
| TX LE19 Ltd | Real estate | 2021 |
| U Fit Sash Windows Ltd | Administrative & support | 2016 |
| UB Boutique Ltd | Wholesale & retail | 2017 |
| UB Spicy Chicken Ltd | Hospitality | 2025 |
| UC Electrics Ltd | Construction | 2021 |
| UCA Rail Limited | Construction | 2023 |
| Udigitalise Ltd | Information & communication | 2022 |
| UFS London Ltd | Arts & recreation | 2023 |
| UHM Investments Ltd | Other services | 2025 |
| UK Black Taxi Limited | Transport & logistics | 2017 |
| UK Fleet Care Ltd | Wholesale & retail | 2024 |
| UK Global Auto Exports Ltd | Wholesale & retail | 2017 |
| UK Italians Limited | Hospitality | 2018 |
| UK Market Management Limited | Professional & scientific | 2020 |
| UK Martial Arts and Fitness Academy Limited | Other services | 2014 |
| UK Overseas Investments Ltd | Wholesale & retail | 2014 |
| UK Power Skills Training Limited | Professional & scientific | 2026 |
| UK Sash Windows Limited | Construction | 2024 |
| Ukmaafa Professional Development Limited | Education | 2026 |
| UKR Roofing Ltd | Construction | 2022 |
| Ulker Limited | Wholesale & retail | 2024 |
| ULTIM8 Sports Limited | Other services | 2014 |
| Ultima Security Ltd | Wholesale & retail | 2020 |
| Ultimate Family Support Service Ltd | Education | 2024 |
| Ultra Football Club Limited | Arts & recreation | 2022 |
| Unboxppc Ltd | Professional & scientific | 2025 |
| Unfiltrd Ltd | Professional & scientific | 2026 |
| Unicaf Ltd | Education | 2019 |
| Unicorn Automotive Limited | Manufacturing | 2010 |
| Unified Boxing Ltd | Wholesale & retail | 2020 |
| Unite Care Agency Ltd | Administrative & support | 2016 |
| Unite Creative Limited | Professional & scientific | 2012 |
| United Mindz C.I.C. | Health & social care | 2025 |
| Unity Group Enterprise Limited | Wholesale & retail | 2016 |
| Upcycled Corporate & Commercial Wear Limited | Wholesale & retail | 2021 |
| Upcycled Medical Limited | Manufacturing | 2021 |
| Upcycled Plastics Limited | Manufacturing | 2020 |
| Upper Clapton Supermarket Limited | Wholesale & retail | 2007 |
| Upshire Hall Barns LLP | | 2024 |
| Upshire Hall Ltd | Construction | 2021 |
| Upshire Skips Limited | Transport & logistics | 2014 |
| Upshire Trade Centre Ltd | Real estate | 2023 |
| Upshire Wealth Management Ltd | Real estate | 2019 |
| Upton Bar Ltd | Hospitality | 2024 |
| Urbnsocial Ltd | Professional & scientific | 2021 |
| Uruci Holdings Limited | Financial services | 2024 |
| Uruci Investments Limited | Real estate | 2024 |
| Usindustout Ltd | Administrative & support | 2024 |
| UT Tutoring Limited | Education | 2024 |
| Utilities for Properties Rented OUT Ltd | Administrative & support | 2024 |
| Utilities Training Centre Limited | Education | 2016 |
| Uygar Ltd | Hospitality | 2015 |
| V Circle Limited | Financial services | 2025 |
| V V Investment & Management Services Ltd | Construction | 2018 |
| V&B Properties Limited | Real estate | 2021 |