| Thremhall Estates Limited | Real estate | 2011 |
| THS Consultants Limited | Professional & scientific | 2024 |
| Tian Cheng Beauty Limited | Other services | 2022 |
| Tidepost Limited | Other services | 2007 |
| Tietek Ltd | Information & communication | 2022 |
| Tillbrook Group Limited | Manufacturing | 2006 |
| TIM Crowdy Ltd | Professional & scientific | 2020 |
| TIM Moya Tree Services Limited | Professional & scientific | 1995 |
| Tim's Minibus and Private Hire Ltd | Transport & logistics | 2016 |
| Timart LLP | | 2021 |
| Timber and Stone Properties Ltd | Construction | 2019 |
| Timeharvest Limited | Information & communication | 2003 |
| Times Like These Therapy Ltd | Health & social care | 2024 |
| Tipu Ltd | Education | 2023 |
| Tisserand English Gardens Ltd | Administrative & support | 2015 |
| Titan Taxis Bishops Stortford Ltd | Transport & logistics | 2020 |
| Titan Wealth Management Limited | Professional & scientific | 2020 |
| Tittensor and Co. Limited | Professional & scientific | 2019 |
| TJ Higgs Dragonfly Academy Ltd | Education | 2025 |
| TJ Hudson Building Services Ltd | Water & waste | 2025 |
| TJB Roofing Limited | Construction | 2007 |
| TJC Consult Limited | Professional & scientific | 2026 |
| TK Energy Group Ltd | Construction | 2025 |
| TK Properties Maintenance Ltd | Construction | 2025 |
| TKH Estates Limited | Real estate | 2026 |
| Tlalli Limited | Professional & scientific | 2020 |
| TMF Consultants (PVT) Limited | Financial services | 2008 |
| TOD Education Limited | Education | 2017 |
| Toffee AI Limited | Information & communication | 2026 |
| TOG Construction Limited | Construction | 2019 |
| Together Design and Build Ltd | Construction | 2025 |
| Tolley’S Garden Services Limited | Administrative & support | 2025 |
| TOM Pinchard Coaching Ltd | Professional & scientific | 2022 |
| Tomcharles Limited | Professional & scientific | 2021 |
| Tomei to YOU Limited | Real estate | 2022 |
| Tommy Honda Limited | Professional & scientific | 2026 |
| Tonghao Limited | Professional & scientific | 2016 |
| Toni Dicks Ltd | Education | 2015 |
| Top Brand Workwear Ltd | Administrative & support | 2005 |
| Top Tier Electrical Services Ltd | Construction | 2021 |
| Topgrade Electrical and Plastering Limited | Construction | 2006 |
| Topsoil and Aggregates Ltd | Construction | 2025 |
| Totally Hooked Ltd | Wholesale & retail | 2020 |
| Toucan Internet LLP | | 2005 |
| Touch Think Limited | Professional & scientific | 2011 |
| Touchwood Online Enterprises Limited | Wholesale & retail | 2013 |
| Tower Packaging Ltd | Administrative & support | 2025 |
| Tower Property Management Ltd | Construction | 2016 |
| Tower View Estate Management Limited | Households | 2016 |
| Town and Country Real Estate Investments Ltd | Real estate | 2021 |
| Town of Tickets Ltd | Administrative & support | 2026 |
| Townhouse Ceramics Ltd | Other services | 2025 |
| TPI Interiors Ltd | Wholesale & retail | 2018 |
| Tpio Ltd | Financial services | 2018 |
| Track 90 Ltd | Information & communication | 2025 |
| Trade AS DDS Couriers Ltd | Transport & logistics | 2024 |
| Trade BOS Ltd | Administrative & support | 2024 |
| Trame Fabric Ltd | Construction | 2026 |
| Transfast Services Ltd | Wholesale & retail | 2023 |
| Transinnovate Consulting Ltd | Professional & scientific | 2026 |
| Transition 2 Limited | Professional & scientific | 2011 |
| Trav Savvy Claims Ltd | Administrative & support | 2025 |
| Travelling Natural History Ltd | Education | 2024 |
| Travelstylers Ltd | Administrative & support | 2020 |
| Traye Ltd | Real estate | 2023 |
| Treadstone Developments Ltd | Construction | 2024 |
| Treaty Developments Limited | Construction | 2014 |
| Treble Recruitment Ltd | Professional & scientific | 2025 |
| Treevolution Tree and Hedge Services Ltd | Agriculture & fishing | 2021 |
| Trendceilings Limited | Construction | 2015 |
| Trenoweth Holdings Ltd | Financial services | 2024 |
| Trevor Arms Glynde Ltd | Manufacturing | 2025 |
| Trevor James Roofing Ltd | Construction | 2026 |
| Trew Quantity Surveying Limited | Professional & scientific | 2023 |
| Tria Tributum Limited | Professional & scientific | 2026 |
| Trilad Accountants London Ltd | Professional & scientific | 2021 |
| Trim LOW Risk Ltd | Wholesale & retail | 2026 |
| Trinergy Integrated Energy Solutions Limited | Administrative & support | 1992 |
| Trinite Property Solutions Ltd | Construction | 2021 |
| Trinity Ductwork Services Limited | Construction | 2022 |
| Tripmemo Ltd | Information & communication | 2025 |
| Troise & Sons Barber Shop Ltd | Other services | 2018 |
| True ELK Limited | Administrative & support | 2021 |
| True Heading Ltd | Professional & scientific | 2021 |
| True Tone Media Ltd | Information & communication | 2025 |
| Truebeat Ltd | Extraterritorial | 2022 |
| Trueset Construction Limited | Construction | 2024 |
| Truly Eventful Limited | Professional & scientific | 2005 |
| Trusted Energy Limited | Energy | 2017 |
| Truview Electrics Ltd | Construction | 2017 |
| Ts&D Solutions Limited | Administrative & support | 2009 |
| Tsma IT Services Limited | Information & communication | 2021 |
| Tsma Property Investment Ltd | Real estate | 2025 |
| TST Customs Ltd | Wholesale & retail | 2023 |
| Tsuistalk Production Limited | Information & communication | 2021 |
| Tt&J Limited | Wholesale & retail | 2020 |
| TU Internet Marketing LLP | | 2007 |
| TU Marketing Ltd | Other services | 2025 |
| Tullig Surveying Ltd | Professional & scientific | 2021 |
| Turk Finans Limited | Financial services | 2009 |