| Thirteen App Ltd | Information & communication | 2026 |
| Thirty-Three (WKD) Limited | Hospitality | 2023 |
| This IS: Interiors Limited | Professional & scientific | 2010 |
| Thistle Property Holdings Group Ltd | Real estate | 2019 |
| Thomas George Contractors Ltd | Construction | 2022 |
| Thomas Jemmeson Engineering Ltd | Professional & scientific | 2021 |
| Thomas Moore Associates Ltd | Water & waste | 2025 |
| Thomas Niamh Contracting Ltd | Construction | 2015 |
| Thomas Simms Limited | Construction | 1957 |
| Thompson Electrical Contracting Limited | Construction | 2006 |
| Thomson Garden Services Limited | Administrative & support | 2021 |
| Thorneline Productions Ltd | Professional & scientific | 2026 |
| Thorner Limited | Extraterritorial | 2015 |
| Thornes Engineering Services Limited | Construction | 2019 |
| Thornes House Care Limited | Health & social care | 2025 |
| Thornes Lane Cafe Limited | Hospitality | 2022 |
| Thornes Lettings and Property Management Ltd | Real estate | 2024 |
| Thornes OFF License Ltd | Wholesale & retail | 2021 |
| Thornes Property Holdings Limited | Households | 2022 |
| Thorneycroft & Co Property Ltd | Real estate | 2015 |
| Thornton Jones Solicitors Limited | Professional & scientific | 2020 |
| Thornton Mead Limited | Professional & scientific | 2009 |
| Thornton Road (Management Company NO.1) Limited | Real estate | 2018 |
| Thorntons Lollies Limited | Manufacturing | 1973 |
| Thothaal Ltd | Hospitality | 2023 |
| Thothaal Property Ltd | Real estate | 2025 |
| Thouvis Software Limited | Administrative & support | 2004 |
| Threadneedle Company Image Limited | Manufacturing | 1940 |
| Threadneedle House Securities Ltd | Financial services | 2019 |
| Three Bears Entertainment Limited | Information & communication | 2016 |
| Three Champs UK Logistics Ltd | Information & communication | 2025 |
| Three Houses Sandal Ltd | Hospitality | 2019 |
| Three PIG Properties Limited | Real estate | 2022 |
| Threemo Legal Services Limited | Professional & scientific | 2018 |
| Thresher Records Ltd | Arts & recreation | 2014 |
| Threshold Mortgages Limited | Financial services | 2003 |
| Thrive Economics Limited | Professional & scientific | 2010 |
| Through Different Eyes Limited | Professional & scientific | 2021 |
| Thsecurity Ltd | Administrative & support | 2017 |
| Thsupportsolutions Limited | Administrative & support | 2025 |
| Thulagasela Health Limited | Health & social care | 2023 |
| Thurston Group Estates 2025 Limited | Financial services | 2025 |
| Thurston Group Limited | Manufacturing | 2025 |
| Tiarcl Limited | Professional & scientific | 2024 |
| Tic-Tac International Limited | Arts & recreation | 2025 |
| Tictac Property Investment Limited | Real estate | 2023 |
| Tidy Limited | Information & communication | 2022 |
| Tier One IT Ltd | Information & communication | 2020 |
| Tiger Enterprises Limited | Administrative & support | 1997 |
| Tigerbloodmuzik Entertainment Limited | Arts & recreation | 2016 |
| Tigerseye.Io Limited | Professional & scientific | 2023 |
| TIH Group Ltd | Real estate | 2025 |
| Tilda Bear Beauty Ltd | Other services | 2023 |
| Tile Central UK Limited | Wholesale & retail | 2014 |
| Tillotson Damp Solutions Limited | Construction | 2019 |
| Tilsatec Limited | Wholesale & retail | 2000 |
| TIM Anelay Associates Limited | Professional & scientific | 2001 |
| TIM Bates Driving Services Ltd | Transport & logistics | 2013 |
| TIM Howe Consultancy Ltd | Professional & scientific | 2001 |
| Tim&Dan Ltd | Wholesale & retail | 2024 |
| Timber Bros Ltd | Construction | 2019 |
| Timber Decking & Cladding Association Ltd. | Professional & scientific | 1998 |
| Timberhaus Ltd | Construction | 2025 |
| Timberstruc Limited | Manufacturing | 2019 |
| Time 2 Shine Valeting Ltd | Wholesale & retail | 2026 |
| Time Communication Solutions Limited | Information & communication | 2001 |
| Time for Solar Ltd | Construction | 2023 |
| Timeless Heart Limited | Wholesale & retail | 2025 |
| Timeless Original Properties Limited | Households | 2023 |
| Tina Store Ltd | Wholesale & retail | 2026 |
| Tingeys Airports Ltd | Transport & logistics | 2025 |
| Tingeys Hemsworth Ltd | Transport & logistics | 2020 |
| Tingley 1 Stop Stores Ltd | Wholesale & retail | 2024 |
| Tingley Athletic FC Limited | Arts & recreation | 2015 |
| Tingley Motor Group Ltd | Wholesale & retail | 2022 |
| Tingley Store Ltd | Wholesale & retail | 2014 |
| Tinico Limited | Wholesale & retail | 2026 |
| Tinisi Limited | Professional & scientific | 2021 |
| Tinkerbell Cavern Ltd | Wholesale & retail | 2024 |
| Tinkermed Ltd | Health & social care | 2024 |
| Tiny Forrest Consulting Limited | Administrative & support | 2025 |
| Tiny Tribe Play Cafe Ltd | Hospitality | 2025 |
| Tipsy FOX Limited | Manufacturing | 2021 |
| Tirumala Limited | Health & social care | 2022 |
| Tisomi (UK) Ltd | Manufacturing | 2005 |
| Titan Motorcycles Ltd | Wholesale & retail | 2023 |
| Titan Pest Control Ltd | Construction | 2026 |
| Titancore Technologies Limited | Information & communication | 2025 |
| Titles - on Limited | Professional & scientific | 2018 |
| TIU Joinery & Framing Ltd | Construction | 2025 |
| Tizar Site Services Ltd | Construction | 2023 |
| TJ Express Limited | Transport & logistics | 2025 |
| TJ Fire Compliance Ltd | Construction | 2026 |
| TJC Designs Ltd | Professional & scientific | 2022 |
| TJC Enterprises Limited | Manufacturing | 2024 |
| TK Fabrications (UK) Limited | Manufacturing | 2011 |
| TK Traders Limited | Wholesale & retail | 2025 |
| TKJ Global Media Ltd | Information & communication | 2012 |
| TKN Teesside Limited | Professional & scientific | 2020 |
| Tktelite Ltd | Administrative & support | 2026 |