| T-Scape Nominees Limited | Administrative & support | 2025 |
| T. J. Cottis Transport Limited | Water & waste | 2000 |
| T.A.B. Sheet Fabrications Limited | Manufacturing | 1990 |
| T.M. Walden Limited | Construction | 1998 |
| T.P. Flat Services (2) Limited | Households | 1977 |
| T.W. Pallets (Thurrock) Limited | Other services | 2007 |
| T4 Build Limited | Real estate | 2026 |
| T8 Invest Limited | Real estate | 2022 |
| TAB IT Ltd | Information & communication | 2025 |
| Tabet Buildings Limited | Real estate | 1966 |
| TAC (APA) Ltd | Construction | 2024 |
| TAG Productions Limited | Information & communication | 2020 |
| Take Two London Limited | Professional & scientific | 2014 |
| TAL Services Limited | Professional & scientific | 2021 |
| Tales by Lunar Light Ltd | Information & communication | 2023 |
| Talisman Training Limited | Education | 2024 |
| Tally HO Experiences Ltd | Wholesale & retail | 2015 |
| Talstone Property Ltd | Real estate | 2023 |
| Tames Healthcare Limited | Wholesale & retail | 2021 |
| Tammy Thomas Ltd | Other services | 2025 |
| Tangerine Leigh Limited | Wholesale & retail | 2016 |
| Tapp'D Cocktails Ltd | Manufacturing | 2019 |
| Tappd Group Ltd | Manufacturing | 2023 |
| Tarko Limited | Construction | 2011 |
| Taskpower Ltd | Professional & scientific | 2017 |
| Taste of Madeira Ltd | Hospitality | 2025 |
| Tawny OWL Properties Limited | Construction | 2017 |
| Tax Help Direct Limited | Professional & scientific | 2003 |
| Tax Made Simple T/A Innovation 4 Business Limited | Professional & scientific | 2014 |
| Taylor & Partners Consulting Limited | Professional & scientific | 2018 |
| Taylor Perry Heating Ltd | Construction | 2015 |
| TB Function Limited | Hospitality | 2026 |
| TBM Aviation LLP | | 2017 |
| Tcalm Solutions Ltd | Information & communication | 2014 |
| TCC Mechanical Services Limited | Professional & scientific | 2025 |
| Tccw Electrical Limited | Construction | 2023 |
| Td&H Restaurants Limited | Hospitality | 2017 |
| Tea Desire Ltd | Wholesale & retail | 2025 |
| Teaktree Construction Ltd | Construction | 2022 |
| Team Jase Limited | Other services | 2023 |
| Techers Ltd | Manufacturing | 2019 |
| Techniques (London) Ltd | Other services | 2014 |
| Tecme Group Ltd | Households | 2021 |
| Tecme Services Ltd | Construction | 2024 |
| Tectrading UK Limited | Wholesale & retail | 2008 |
| TED Walker Consultancy Ltd | Construction | 2021 |
| Tediam Consulting Limited | Professional & scientific | 2022 |
| TEG Developments (Essex) Ltd | Construction | 2023 |
| Tek-Match Limited | Administrative & support | 2024 |
| Tekmeld Limited | Information & communication | 2011 |
| Tekton Management London Limited | Administrative & support | 2021 |
| Tel-Med UK Limited | Professional & scientific | 2021 |
| Telenetic Systems Limited | Information & communication | 2019 |
| Telltale Locations Ltd | Information & communication | 2015 |
| Temperature Management Limited | Construction | 2014 |
| Templeton Flagg Limited | Real estate | 2012 |
| Temporary Vision Limited | Professional & scientific | 2020 |
| Tender Shoots (Essex) Limited | Education | 2016 |
| Tendring Express Services Limited | Transport & logistics | 2010 |
| Terrence James Construction Limited | Construction | 2021 |
| Terry Paul Jewellery Limited | Wholesale & retail | 2016 |
| Terryco Limited | Real estate | 2023 |
| TES Vehicles LLP | | 2025 |
| Tessaclark Ltd | Real estate | 2024 |
| Tessari & Sollazzi Studio Ltd | Professional & scientific | 2015 |
| Test-Based Nutrition + Performance Ltd | Information & communication | 2024 |
| Testcom Management Ltd | Construction | 2020 |
| Tetra Energies Ltd | Mining & quarrying | 2022 |
| Tetra Energy Alpha Ltd | Mining & quarrying | 2022 |
| Tetra Energy Beta Ltd | Mining & quarrying | 2022 |
| Tetra Energy Gamma Ltd | Mining & quarrying | 2015 |
| Tetra Energy UK Onshore Ltd | Mining & quarrying | 2006 |
| Tetters Limited | Financial services | 2023 |
| Teucer Healthcare Enterprises Limited | Wholesale & retail | 2020 |
| Textile Trader Limited | Professional & scientific | 2009 |
| Teybrook Project Management Ltd | Professional & scientific | 2024 |
| Tffg Holdings Limited | Financial services | 2025 |
| Tffg Limited | Administrative & support | 2009 |
| TFT Consultancy Limited | Administrative & support | 2010 |
| TG & Co Roofing and Building Limited | Construction | 2019 |
| TG Aviation Services Limited | Manufacturing | 2026 |
| TGC Home Improvements Limited | Construction | 2012 |
| TGC Limited | Extraterritorial | 2008 |
| TGM Fire Protection Limited | Public administration | 2015 |
| Thai Enterprises (Essex) Limited | Real estate | 2015 |
| Thai Jasmin Ltd | Other services | 2025 |
| Thames Gateway Electrical Contractors Ltd | Construction | 2009 |
| Thames Gateway Roadways Limited | Transport & logistics | 2007 |
| Thames Shipping Limited | Transport & logistics | 2008 |
| Thames Steel (Services) Limited | Manufacturing | 2013 |
| Thamescraft Limited | Transport & logistics | 2016 |
| Thameside Fire Stopping Limited | Construction | 2013 |
| Thameside Pathways Limited | Health & social care | 2025 |
| Thanet Court Limited | Administrative & support | 2001 |
| Thassit Limited | Construction | 2025 |
| That's Bizarre Ltd | Wholesale & retail | 2018 |
| THD Maintenance Group Limited | Construction | 2020 |
| THE Ackley Trading Company Ltd | Wholesale & retail | 2020 |
| THE ACT STD. Limited | Wholesale & retail | 2023 |
| THE Admiral's ARM Limited | Hospitality | 2018 |