| Thegenco Ltd | Wholesale & retail | 2021 |
| Thegoldexchange Ltd | Wholesale & retail | 2024 |
| Themis Planning & Project Management Limited | Construction | 2014 |
| Theos Food Company PEO Limited | Administrative & support | 2025 |
| Thephonecompany Limited | Energy | 2018 |
| Theppfco Ltd | Wholesale & retail | 2025 |
| Therapy With Eliza Ltd | Health & social care | 2026 |
| Therion Investment Holdings Limited | Financial services | 2025 |
| Thermalweld Global Ltd | Extraterritorial | 2025 |
| Thetis Bidco Limited | Financial services | 2021 |
| Thetis Midco Limited | Financial services | 2021 |
| Thetis Parentco Limited | Financial services | 2021 |
| THH Medics Ltd | Health & social care | 2023 |
| Thik Healthcare Ltd | Health & social care | 2017 |
| Think Differently Dyslexia Support Limited | Education | 2026 |
| Think Wills & Probate Ltd | Other services | 2002 |
| Thinkbig IT Solutions Limited | Information & communication | 2018 |
| Thinking Search Limited | Administrative & support | 2014 |
| Third Wave Investments Limited | Financial services | 2023 |
| Thirteen Firs Ltd | Households | 2026 |
| This Wild Isle Limited | Wholesale & retail | 2025 |
| Thjh Limited | Education | 2021 |
| Thomas & Young Limited | Professional & scientific | 2000 |
| Thomas and Ebrey Limited | Arts & recreation | 2005 |
| Thomas Walker Enterprises Ltd | Administrative & support | 2018 |
| Thomason Solutions Ltd | Wholesale & retail | 2020 |
| Thomson Grace Wealth Ltd | Financial services | 2022 |
| Thornbridge Consultancy Ltd | Professional & scientific | 2025 |
| Thornbury Court (Isleworth) RTM Company Limited | Real estate | 2014 |
| Thorne Homes Limited | Real estate | 2016 |
| Thorneloe Developments Ltd | Real estate | 2016 |
| Thornescroft Properties Ltd | Real estate | 2021 |
| Thornton MOT Ltd | Wholesale & retail | 2020 |
| Thornton Property Solutions Ltd | Construction | 2022 |
| Thoroughbred Jewellery Limited | Extraterritorial | 2012 |
| Those WHO Wander Salon Ltd | Other services | 2023 |
| Thotts & Co Ltd | Real estate | 2025 |
| Three Acres Consultancy Ltd | Professional & scientific | 2015 |
| Three Cocks Lane (Offenham) Limited | Construction | 2023 |
| Three Minute Silence Limited | Professional & scientific | 2004 |
| Thrive Promo Ltd | Arts & recreation | 2025 |
| Thrivewell Properties Limited | Real estate | 2024 |
| Thriving Connections C.I.C. | Education | 2024 |
| Thunder Cargo Ltd | Transport & logistics | 2025 |
| Thylacine Consulting Ltd | Professional & scientific | 2025 |
| Tibbatts & Co Holdings Limited | Financial services | 1979 |
| Tice Tech Community Interest Company | Administrative & support | 2025 |
| Tichal Holdings Ltd | Administrative & support | 2026 |
| Tigatech Ltd. | Wholesale & retail | 2021 |
| Tiger BAM Communications Limited | Professional & scientific | 2015 |
| Tiger Catering Limited | Manufacturing | 2024 |
| Tiger Coatings UK Ltd | Wholesale & retail | 2003 |
| Tiger Fibre Limited | Information & communication | 2020 |
| Tiger Truck & Plant Sales Limited | Wholesale & retail | 2021 |
| Tigersreal Ltd | Real estate | 2022 |
| Tile Demand Ltd | Wholesale & retail | 2024 |
| Tilia Community Living Holdco 1 LLP | | 2018 |
| Tilia Community Living Holdco 2 LLP | | 2018 |
| Tilia Community Living LLP | | 2018 |
| Tilia Community Living Topco 1 LLP | | 2018 |
| Tilia Community Living Topco 2 LLP | | 2018 |
| Tilia Cross Keys DEV LLP | | 2017 |
| Tilia Cross Keys Holdco 1 LLP | | 2017 |
| Tilia Cross Keys Holdco 2 LLP | | 2017 |
| Tilia Homes Caledonia Limited | Construction | 1988 |
| Tilia Homes Developments 1 Limited | Financial services | 2023 |
| Tilia Homes Limited | Construction | 1963 |
| Tilia Homes Northern Limited | Extraterritorial | 2006 |
| Tilia Land Limited | Extraterritorial | 1988 |
| Tilia Living Developments Limited | Construction | 2020 |
| Tilia Partnership Homes Limited | Construction | 2001 |
| Tilia Sovereign LLP | | 2017 |
| Tiling Logistics Limited | Wholesale & retail | 2013 |
| Tillman Medicolegal Limited | Health & social care | 2021 |
| Tilser & SON Construction Ltd | Construction | 2021 |
| Tilton Strada Ltd | Professional & scientific | 2026 |
| TIM Bailey Engineering Services Limited | Manufacturing | 2019 |
| TIM Bailey Offshore and EU Services Limited | Professional & scientific | 2024 |
| TIM Drohan Trading Investments Limited | Real estate | 1993 |
| Timber Frame Services Limited | Manufacturing | 1982 |
| Timberdel Consulting Services Limited | Professional & scientific | 2019 |
| Timberhonger Lane Bespoke Property Ltd | Construction | 2025 |
| Timboard Limited | Professional & scientific | 1970 |
| Time 2 Shine Warwick Ltd | Administrative & support | 2024 |
| Time Saving Experts Limited | Administrative & support | 2009 |
| Time to PAY Limited | Professional & scientific | 2010 |
| Timeguard Health & Beauty Limited | Extraterritorial | 2018 |
| Timeless Composites Ltd | Construction | 2020 |
| Timeless Consultancy's Ltd | Other services | 2022 |
| Timeless Energy Ltd | Construction | 2011 |
| Timeless Housing Ltd | Hospitality | 2025 |
| Timglobal Ltd | Information & communication | 2025 |
| Timmins Investments Limited | Financial services | 2022 |
| Tiny Book of Clothes Limited | Wholesale & retail | 2024 |
| Tiny Giant Group Limited | Financial services | 2021 |
| Tiny Idols Ltd | Wholesale & retail | 2026 |
| Tiny Tots Cafe Ltd | Hospitality | 2024 |
| Tiobo Limited | Information & communication | 2008 |
| Tipple TAP Ltd | Hospitality | 2018 |
| Tirebuck Recruitment Ltd | Administrative & support | 2009 |