| TRILOK46 Company Limited | Health & social care | 2018 |
| Trimex Auto Ltd | Wholesale & retail | 2020 |
| Trimex Homes Ltd | Real estate | 2021 |
| Trimex UK Limited | Wholesale & retail | 2002 |
| Trinity & - Co Limited | Wholesale & retail | 2024 |
| Triple Glazing Windows Ltd | Other services | 2023 |
| Triple O Homes Limited | Real estate | 2021 |
| Triple SIX International Ltd | Wholesale & retail | 2017 |
| Trivauras Limited | Education | 2026 |
| TRS Contract Services Ltd | Real estate | 2022 |
| Truck-Tsl Ltd | Transport & logistics | 2018 |
| Truckster Haulage Limited | Transport & logistics | 2025 |
| Truckster Haulage Services Ltd | Transport & logistics | 2019 |
| True Sterling Properties Ltd | Construction | 2024 |
| Trunking EB Ltd | Transport & logistics | 2026 |
| Trust Motorcars Ltd | Wholesale & retail | 2020 |
| Trustools Ltd | Wholesale & retail | 2019 |
| Trustus Limited | Health & social care | 2019 |
| Trustus Property Limited | Real estate | 2020 |
| Trythemarket Ltd | Real estate | 2023 |
| Tsai Ltd | Information & communication | 2020 |
| TSF Electric Ltd | Construction | 2017 |
| Tsigkos Ltd | Transport & logistics | 2018 |
| TSM Consultants UK Ltd | Information & communication | 2008 |
| TSM Medics Ltd | Health & social care | 2021 |
| TSO Properties Limited | Real estate | 2022 |
| Ttmanagementcorp Ltd | Construction | 2026 |
| TTS Management Solutions Limited | Professional & scientific | 2023 |
| Tudor Court (Hanworth) Management Co. Limited | Households | 1970 |
| Tudor Park Education Trust | Education | 2011 |
| Tulip Media Ltd | Professional & scientific | 2020 |
| Tulis Consulting Ltd | Information & communication | 2016 |
| TUN Engineering Ltd | Construction | 2018 |
| Tuned Performance UK Ltd | Wholesale & retail | 2026 |
| Turbowood WB Limited | Construction | 2026 |
| TV Productions Limited | Information & communication | 2021 |
| TW 25 Limited | Real estate | 2015 |
| TW Bathrooms Plumbing & Heating Ltd | Wholesale & retail | 2019 |
| TW Construction Group Ltd | Construction | 2026 |
| TW Driving School Ltd | Education | 2023 |
| TW Maintenance & Gardening Ltd | Administrative & support | 2026 |
| TW13 Ltd | Real estate | 2026 |
| TW14 Hide Away Cafe Ltd | Hospitality | 2020 |
| TW18 Company Ltd | Information & communication | 2009 |
| Twickenham Construction Limited | Construction | 2018 |
| Twinkle Trove Ltd | Wholesale & retail | 2025 |
| Twisty Weekend Limited | Wholesale & retail | 2023 |
| Two Brown Bears Limited | Real estate | 2026 |
| TYA Gurung Limited | Real estate | 2025 |
| Tyre Bay Group Ltd | Wholesale & retail | 2016 |
| Tyres Express Limited | Wholesale & retail | 2023 |
| TYRES2ROAD Limited | Wholesale & retail | 2025 |
| U-Works Services Ltd | Manufacturing | 2017 |
| U-Works Solutions Ltd | Manufacturing | 2018 |
| Ubaego Services Limited | Health & social care | 2026 |
| Ucutz Unisex Ltd | Other services | 2024 |
| UGS Media Limited | Arts & recreation | 2018 |
| UK Aerospace Industry Limited | Transport & logistics | 2009 |
| UK China Northeast Entrepreneur Association | Other services | 2023 |
| UK Inner Mongolia Business Association | Other services | 2012 |
| UK Motor Sales Limited | Wholesale & retail | 2023 |
| UK Pumping Ltd | Manufacturing | 2022 |
| UK Safety Standard Limited | Construction | 2019 |
| UK Shutter Repair Ltd | Manufacturing | 2023 |
| UK Smartplan Limited | Professional & scientific | 2016 |
| UK Tamil Penngal Limited | Other services | 2020 |
| Ultra FIX Ltd | Construction | 2019 |
| Ultra Property Management Limited | Real estate | 2022 |
| Ultra Software Limited | Information & communication | 2009 |
| Umair Sajid Ltd | Wholesale & retail | 2024 |
| Umut Bulut 68 Ltd | Hospitality | 2018 |
| UNA Fresh and Co Ltd | Administrative & support | 2026 |
| Uncle SAM Security Services Ltd | Administrative & support | 2024 |
| Undo Records Limited | Manufacturing | 2015 |
| Uneek Wholesale Ltd | Administrative & support | 2017 |
| Unicorn Shipping Limited | Transport & logistics | 2008 |
| Unicup.Vending Ltd | Wholesale & retail | 2025 |
| Unified Haulier Ltd | Transport & logistics | 2019 |
| Union Building Contractor Ltd | Construction | 2024 |
| Unipartner Global Ltd | Information & communication | 2024 |
| Unique Air Express Limited | Transport & logistics | 2018 |
| Unique Vapes Limited | Wholesale & retail | 2019 |
| Unissen Services Ltd | Construction | 2025 |
| United Parts & Service Limited | Manufacturing | 2025 |
| United Repairs Limited | Manufacturing | 2014 |
| Unitedlondonoverseas Ltd | Information & communication | 2025 |
| Unity Creatorz Ltd | Arts & recreation | 2026 |
| Univ Global Ltd | Education | 2020 |
| Universal Business Solution Limited | Wholesale & retail | 2020 |
| Universal College London Ltd | Education | 2025 |
| Universal Food Distributor Ltd | Wholesale & retail | 2025 |
| Universe Logistics Ltd | Transport & logistics | 2017 |
| Unpopular Favour Limited | Health & social care | 2018 |
| Untiedvision Ltd | Wholesale & retail | 2021 |
| UP Skill Digital Tech Ltd | Wholesale & retail | 2022 |
| Upper Berkeley Care Ltd | Health & social care | 2021 |
| UR Kitchen & Bath Ltd | Wholesale & retail | 2016 |
| UR Stone Tools Ltd | Wholesale & retail | 2023 |
| Urban Building Limited | Construction | 2025 |
| Urban Define Ltd | Real estate | 2025 |