| Thompson Hughes Ltd | Professional & scientific | 2015 |
| Thompson Safety Services Ltd | Professional & scientific | 2026 |
| Thomson Electrical Solutions Ltd | Construction | 2019 |
| Thor Telecommunications Limited | Professional & scientific | 2019 |
| Thorburn HR Consulting Limited | Administrative & support | 2023 |
| Thornbury Spice Ltd | Hospitality | 2025 |
| Thorpe Close (Biddenham) Management Company Limited | Real estate | 1996 |
| Thoughtclay Consulting Limited | Information & communication | 2014 |
| Thoughts to Form Limited | Professional & scientific | 2025 |
| Thread and Bloom Limited | Professional & scientific | 2018 |
| Threads (LDN) Ltd | Wholesale & retail | 2025 |
| Three Angels Woodland Farmacy Ltd | Agriculture & fishing | 2020 |
| Three Colours Limited | Administrative & support | 2008 |
| Three Counties Landscapes Ltd | Administrative & support | 2018 |
| Three Counties Moves Ltd | Transport & logistics | 2017 |
| Three Counties Storage Ltd | Transport & logistics | 2021 |
| Three J3W3LS Ltd | Health & social care | 2022 |
| Three Shires Property Services Ltd | Construction | 2012 |
| Three Singhs Limited | Wholesale & retail | 2013 |
| Threelink Global Ltd | Real estate | 2023 |
| Thrivawell Ltd | Health & social care | 2024 |
| Thrive Online Design Ltd | Professional & scientific | 2024 |
| Thrive Outside Outdoor Learning Centre Limited | Education | 2022 |
| Thrive Play Therapy CIC | Health & social care | 2024 |
| Thrive Sport and Wellbeing CIC | Arts & recreation | 2026 |
| Thrive Together Solutions Limited | Health & social care | 2016 |
| Throughput Focus Ltd | Information & communication | 2013 |
| Thunder Run Limited | Extraterritorial | 2024 |
| Thunderbolt Scaffolding Solutions Ltd | Construction | 2010 |
| Thundervolt Ltd | Wholesale & retail | 2017 |
| Thurlyn Limited | Extraterritorial | 2010 |
| Thurstons Attractions Ltd | Arts & recreation | 2015 |
| Thurstons Attractions Token Events Ltd | Arts & recreation | 2021 |
| THX Group Ltd | Financial services | 2025 |
| THX Holdings Ltd | Financial services | 2019 |
| Tian Tian Hospitality Limited | Hospitality | 2023 |
| Tibbs Dementia Foundation | Health & social care | 2015 |
| Tiber Equity Holdings Ltd | Real estate | 2026 |
| TIC Engineering Consultancy Limited | Professional & scientific | 2016 |
| Ticau Cristina Ltd | Other services | 2024 |
| Ticau Daniel Ltd | Other services | 2026 |
| Tick Education Ltd | Education | 2020 |
| Tiddlywinks Day Nursery (Kempston Rural) Ltd | Education | 2014 |
| Tier One Developments Ltd | Construction | 2006 |
| Tiger CNC Ltd | Professional & scientific | 2025 |
| Tigercub Limited | Professional & scientific | 2007 |
| Tiggi London Limited | Wholesale & retail | 2022 |
| Tigi Laundry Limited | Other services | 2022 |
| Tiho Heating Limited | Construction | 2012 |
| Tilehall Limited | Administrative & support | 2005 |
| Tilera Limited | Manufacturing | 2025 |
| Tilsley Meridian Ltd | Real estate | 2025 |
| TIM Anderson Property Ltd | Real estate | 2018 |
| TIM Cole Consultancy Limited | Professional & scientific | 2014 |
| TIM Corry Investments Limited | Professional & scientific | 2024 |
| TIM Kemp Accountancy Services Limited | Professional & scientific | 2007 |
| TIM Woolley Consulting Limited | Information & communication | 1996 |
| Timber Constructions Limited | Construction | 1980 |
| Time & Attendance (UK) Limited | Manufacturing | 2002 |
| Timecare Limited | Financial services | 2021 |
| Timeless Care Ltd | Administrative & support | 2014 |
| Timeless Event Consulting Ltd | Administrative & support | 2023 |
| Timeless Moments by Reena Limited | Other services | 2025 |
| Times Tables Rock Stars Limited | Extraterritorial | 2022 |
| Timev M & S Ltd | Wholesale & retail | 2024 |
| Tindall Property (1) Limited | Real estate | 2025 |
| Tindall Property Management Ltd | Real estate | 2021 |
| Tinvan Investments Limited | Wholesale & retail | 2011 |
| Tinware Direct Limited | Administrative & support | 2001 |
| Tiny Body Loud Mind Limited | Information & communication | 2025 |
| Tiny's Properties Ltd | Real estate | 2025 |
| Tiosh Ltd | Education | 2023 |
| Tipi Luxe Events Ltd | Other services | 2025 |
| Tipsy Dragon Holdings Ltd | Wholesale & retail | 2025 |
| Tiro Partners Limited | Professional & scientific | 2012 |
| Tiska Karate Limited | Arts & recreation | 2012 |
| Tiska Limited | Arts & recreation | 1999 |
| Tiska Promotions Ltd | Arts & recreation | 1997 |
| Tiska Publishing Limited | Information & communication | 1997 |
| Tisoart Ltd | Manufacturing | 2019 |
| Titan Accounting Services Ltd. | Construction | 2023 |
| Titan Figures Limited | Professional & scientific | 2025 |
| Titan Sky Ltd | Water & waste | 2021 |
| Titan Stories Ltd | Information & communication | 2023 |
| Titanium Dent Ltd | Health & social care | 2019 |
| Titansteel Work Ltd Limited | Construction | 2026 |
| Titch TV Ltd | Information & communication | 2014 |
| Titus Royce Asset Management Ltd | Real estate | 2019 |
| Tivana &Co Limited | Health & social care | 2023 |
| TJ Freestyle Academy Ltd | Education | 2025 |
| TJD Estates Ltd | Real estate | 2023 |
| TJD Land Ltd | Administrative & support | 2013 |
| TJD Limited | Extraterritorial | 2008 |
| TJD North Ltd | Construction | 2023 |
| TJD South Limited | Construction | 2023 |
| TJF Projects Ltd | Construction | 2026 |
| Tjsa Ltd | Wholesale & retail | 2024 |
| TKR Consultancy Ltd | Construction | 2011 |
| Tkuk Limited | Manufacturing | 2017 |
| TLB Heating Ltd | Construction | 2025 |