| Towersit Limited | Professional & scientific | 2019 |
| Towmove Ltd | Transport & logistics | 2024 |
| Town & Country Drainage Limited | Water & waste | 2014 |
| Towne Constructions Specialists Ltd | Construction | 2025 |
| Townjoin Property Management Limited | Households | 1987 |
| Towns & Tadman Limited | Administrative & support | 2015 |
| Towntake Property Management Limited | Households | 1991 |
| Toybox Pre-School Limited | Education | 2018 |
| Toye Services Ltd | Administrative & support | 2021 |
| Toyola Ltd | Wholesale & retail | 2019 |
| TP Assets Ltd | Construction | 2020 |
| TPH Group Limited | Administrative & support | 2020 |
| TPH Solutions Ltd | Administrative & support | 2024 |
| Tplm Holdings Limited | Households | 2025 |
| TPR Electrical Services Limited | Construction | 2014 |
| TR Consultancy Ltd | Wholesale & retail | 2018 |
| Tracey Court (Stanmore) Residents Association Limited | Households | 1999 |
| Tracos Ltd | Construction | 2018 |
| Trade ALL in Limited | Wholesale & retail | 2022 |
| Trade Autos Ltd | Wholesale & retail | 2022 |
| Trade Global Ventures Ltd | Wholesale & retail | 2025 |
| Trade Safe Products Limited | Construction | 2008 |
| Trade Smart Motors Ltd | Wholesale & retail | 2021 |
| Trade United Limited | Wholesale & retail | 2018 |
| Tradehq Ltd | Other services | 2025 |
| Trademark Design Limited | Professional & scientific | 2003 |
| Tradeo Limited | Wholesale & retail | 2024 |
| Traderdiaz Limited | Professional & scientific | 2026 |
| Trades Direct (London) Ltd | Construction | 2015 |
| Trades YOU Like Ltd | Construction | 2024 |
| Traditionally Broom'D Ltd | Administrative & support | 2022 |
| Traffi-Co Limited | Construction | 1998 |
| Traffic Management London Limited | Information & communication | 2005 |
| Trailon Business Solutions (TBS) Limited | Wholesale & retail | 2009 |
| Train I.T Limited | Professional & scientific | 2018 |
| TRAIN4FITNESS.ORG Limited | Education | 2023 |
| Trainer Revival Hub Ltd | Wholesale & retail | 2026 |
| Training Experiences and Masterclasses Ltd | Education | 2019 |
| Training KIT Outside Ltd | Manufacturing | 2023 |
| Traintogetherlondon CIC | Education | 2022 |
| Tram Operations Limited | Transport & logistics | 1995 |
| Tran-Support Limited | Transport & logistics | 2014 |
| Tranche Technologies Limited | Information & communication | 2025 |
| Tranconstructions Limited | Construction | 2021 |
| Tranquil House Limited | Real estate | 2020 |
| Trans-Delta Capital UK Ltd | Financial services | 2023 |
| Transac International Holding Ltd | Administrative & support | 1976 |
| Transac International Limited | Administrative & support | 1979 |
| Transform ME Academy Ltd | Other services | 2020 |
| Transformative AI Limited | Information & communication | 2016 |
| Transglobe Online Limited | Transport & logistics | 2024 |
| Transit Management Limited | Administrative & support | 1952 |
| Transpackprofessional Ltd | Transport & logistics | 2023 |
| Transparent Elements Limited | Manufacturing | 2009 |
| Transversale Ltd | Information & communication | 2011 |
| Transworld INT Ltd | Financial services | 2019 |
| Tratom Limited | Real estate | 2018 |
| Travel Brake Ltd | Administrative & support | 2017 |
| Travel by Victoria and West Ltd | Administrative & support | 2017 |
| Travel Lodge Ltd | Administrative & support | 2024 |
| Travel Monk Europe Ltd | Administrative & support | 2013 |
| Travel the Unknown Ltd | Administrative & support | 2007 |
| Travel Your Way Ltd | Administrative & support | 2025 |
| Travelanalytics.Ai Ltd | Administrative & support | 2023 |
| Travellata Ltd | Administrative & support | 2024 |
| Travelon Services Limited | Administrative & support | 2025 |
| Travgo Services Ltd | Transport & logistics | 2012 |
| Trayam Energy & Automation Limited | Manufacturing | 2025 |
| TRD Liquor Stores Limited | Wholesale & retail | 2021 |
| Treasures and Homes Limited | Manufacturing | 2023 |
| Treats DE LA VIE Ltd | Manufacturing | 2020 |
| Trebor Works Management RTM Company Limited | Households | 2009 |
| Tree One Limited | Real estate | 2018 |
| Tree Tea Ltd | Wholesale & retail | 2019 |
| Tree Three Limited | Real estate | 2019 |
| Tree Two Limited | Real estate | 2019 |
| Tree Wise MEN (S.E.) Ltd | Agriculture & fishing | 2011 |
| Treebird Ltd | Wholesale & retail | 2022 |
| Treehammer Limited | Financial services | 2021 |
| Treelogy FL Ltd | Wholesale & retail | 2025 |
| Treelogy HK Ltd | Wholesale & retail | 2025 |
| Trefusis Court Management Limited | Households | 1981 |
| Trelawney Court Management Company Limited | Households | 1988 |
| Trelawny Homecare Limited | Health & social care | 2026 |
| Trend Setters Enterprises Limited | Wholesale & retail | 2014 |
| Trend Trunk Ltd | Wholesale & retail | 2026 |
| Trendgazers Limited | Wholesale & retail | 2010 |
| Trendsnare Limited | Wholesale & retail | 2017 |
| Trentham Lofts Ltd | Construction | 2015 |
| Trenton Richard Donaldson Limited | Extraterritorial | 2022 |
| Tresid Design & Build Limited | Construction | 2015 |
| Treverrow Farm Ltd | Construction | 2025 |
| Trevi Tiramisu Ltd | Administrative & support | 2019 |
| Trevor Mitchell Building Consultancy Services Limited | Professional & scientific | 2026 |
| TRF Marian Ltd | Transport & logistics | 2026 |
| Triada Capital Limited | Professional & scientific | 2012 |
| Tribal Entertainment Limited | Professional & scientific | 2019 |
| Tribe Urban Limited | Administrative & support | 2018 |
| Tribrosis Limited | Financial services | 2018 |
| Trident Engineering Training Ltd | Education | 2026 |