| Triangle Group Limited | Construction | 2018 |
| Trident London Limited | Professional & scientific | 2011 |
| Triland (Chiltern Street) Limited | Construction | 2009 |
| Trilogie Ltd | Information & communication | 2023 |
| Trinity London Holdings Limited | Financial services | 2018 |
| Tripbuddy Group Ltd | Hospitality | 2024 |
| Tripura Ltd | Financial services | 2022 |
| Trishool Convenience Ltd | Wholesale & retail | 2021 |
| Tristan Real Estate Limited | Financial services | 2020 |
| Triumph Travel Limited | Administrative & support | 2008 |
| Trivantis Services Ltd | Transport & logistics | 2022 |
| Tropical Asset Group Ltd | Real estate | 2025 |
| Trotman Consultancy Ltd | Administrative & support | 2021 |
| Truck & Plant Site Services Ltd | Transport & logistics | 2016 |
| True Flow Solutions Ltd | Construction | 2026 |
| True Projects Limited | Administrative & support | 2021 |
| Truffle Bikinis Limited | Wholesale & retail | 2020 |
| Truss Developments Essex Ltd | Real estate | 2024 |
| Trust Scaffolding (UK) Limited | Construction | 1999 |
| Trust Talented Recruitment Ltd | Administrative & support | 2024 |
| Trusted Care Homes Limited | Health & social care | 2025 |
| Tsso Ltd | Wholesale & retail | 2015 |
| TTM Healthcare Recruitment UK Limited | Administrative & support | 2015 |
| Tucker Group Investments Limited | Construction | 2015 |
| Turavia Ltd | Wholesale & retail | 2018 |
| Turbo Accessory and Parts Ltd | Wholesale & retail | 2021 |
| Turn on the Bright Lights Limited | Professional & scientific | 2025 |
| Turner & Co Group Limited | Financial services | 2025 |
| Turnstone Construction Services Limited | Construction | 2019 |
| Turtledove Creative Ltd | Professional & scientific | 2023 |
| Twelve Castle Management Limited | Real estate | 1981 |
| Twickenham Green Bars Limited | Hospitality | 2023 |
| Twickenham Green Taverns Limited | Hospitality | 2016 |
| Two Acre Homes Ltd | Real estate | 2025 |
| Twpc Ltd | Administrative & support | 2012 |
| Tyers Book Sales Limited | Wholesale & retail | 2002 |
| Tylasys Limited | Information & communication | 2010 |
| Tysl Ltd | Construction | 2026 |
| Tyson Enforcement Limited | Administrative & support | 2026 |
| Uaworkers Carpentery&Joinery Ltd | Manufacturing | 2025 |
| UCT Limited | Information & communication | 1997 |
| UHD Construction Ltd | Construction | 2019 |
| UK Chiken Services Limited | Professional & scientific | 2009 |
| UK Identification Solutions Limited | Information & communication | 2024 |
| UK Nollywood Producers Guild Ltd | Other services | 2014 |
| UK Security & Facilities Ltd | Administrative & support | 2023 |
| UK VAT Advice Limited | Professional & scientific | 2012 |
| UK Water Softeners Limited | Other services | 2022 |
| Ukitb | Information & communication | 2008 |
| Ukws Holdings Limited | Financial services | 2026 |
| UMA Touch Limited | Health & social care | 2022 |
| Umbrella Land and Properties Ltd | Real estate | 2009 |
| Ungra Ltd | Administrative & support | 2017 |
| UNI Applicant Ltd | Education | 2024 |
| Unicorn Legal Consulting Limited | Professional & scientific | 2018 |
| Unidoor Finance Limited | Administrative & support | 2016 |
| Unify Office Solutions Limited | Information & communication | 2017 |
| Union Groceries Limited | Wholesale & retail | 2014 |
| Union IV Group Ltd | Professional & scientific | 2018 |
| Union IV Holdings LLP | | 2017 |
| Union IV Ltd | Administrative & support | 2017 |
| Unique Cosmetics Limited | Wholesale & retail | 1997 |
| Unique London Consultancy Ltd | Real estate | 2020 |
| Unique London Property Management Ltd | Real estate | 2025 |
| Unique Trade Property Limited | Real estate | 2024 |
| United Group 2023 Limited | Financial services | 2023 |
| Universal Car Services Limited | Water & waste | 1991 |
| Universal Integrated Maintenance Limited | Real estate | 1992 |
| Universal Print Management Limited | Other services | 2014 |
| Universal Waste Limited | Water & waste | 2011 |
| Universe Property Ltd | Real estate | 2021 |
| Unscripted Academy Ltd | Education | 2023 |
| Unverco Ltd | Information & communication | 2017 |
| UP 4 Design Ltd | Other services | 2021 |
| Up.Rise Ventures (UK) Ltd | Wholesale & retail | 2018 |
| Uplift Outreach Ltd | Professional & scientific | 2025 |
| Uprise Management Ltd | Households | 2010 |
| Upstage Theatre Company Ltd | Arts & recreation | 2020 |
| Upton Lane Real Estates Ltd | Real estate | 2023 |
| Urantia LLP | | 2008 |
| Urantia Press Limited | Manufacturing | 1999 |
| Urban High Street Limited | Real estate | 2024 |
| Urban Services Property Investments Limited | Real estate | 2022 |
| Urban Structures Construction Limited | Construction | 2019 |
| Urgent Delivery Couriers Limited | Transport & logistics | 2000 |
| Urgent Staffing Recruitment Limited | Administrative & support | 2018 |
| Urology for YOU Ltd | Health & social care | 2012 |
| V & B Property Limited | Real estate | 2014 |
| V & S (NO 8) Limited | Households | 1989 |
| V L H Minibus Ltd | Transport & logistics | 2020 |
| V&A Cleaning Service Ltd | Administrative & support | 2018 |
| V&A Construction Development Ltd | Construction | 2019 |
| V-Styling Ltd | Professional & scientific | 2016 |
| V12 Sterling Limited | Administrative & support | 2026 |
| Valentine Jones Investment Ltd | Real estate | 2023 |
| Valicious Limited | Hospitality | 2025 |
| Valley Hill Builders Merchant Ltd | Wholesale & retail | 2024 |
| Van Wyngaardt Global Limited | Administrative & support | 2023 |
| Vanesa Maza Limited | Information & communication | 2019 |
| Varden Street Limited | Real estate | 2008 |