| Thermodynamics Ltd. | Construction | 2018 |
| THG Property Ltd | Real estate | 2019 |
| Thomas Capital Finance Limited | Financial services | 2014 |
| Thomas Process and Digital Twin Services Limited | Professional & scientific | 2024 |
| Thoroughdata AI Ltd | Wholesale & retail | 2025 |
| Thorpes Physiotherapy Limited | Health & social care | 2012 |
| Thought MAP Ltd | Professional & scientific | 2010 |
| Three Counties Roofing Limited | Construction | 2013 |
| Thrive Studios Limited | Professional & scientific | 2014 |
| Ticino-Desinex Limited | Manufacturing | 1974 |
| Tidal Analytics Limited | Manufacturing | 2023 |
| Tiger Homes Ltd | Real estate | 2020 |
| Tigra Solutions Limited | Professional & scientific | 1996 |
| Tilliot Limited | Real estate | 2024 |
| TIM Carr Consulting Limited | Professional & scientific | 2014 |
| Timber Technology Limited | Construction | 2015 |
| Time Back Solutions Limited | Administrative & support | 2020 |
| Timeless Expeditions Limited | Administrative & support | 2025 |
| Timon Solutions Limited | Professional & scientific | 2017 |
| Timothy Janes Ltd | Professional & scientific | 2019 |
| Tindoh Ltd | Health & social care | 2023 |
| Tinley Property Management Limited | Real estate | 2006 |
| Tinson Construction Limited | Construction | 2019 |
| TJ Milne Solutions Limited | Administrative & support | 2014 |
| Tjbam Limited | Professional & scientific | 2024 |
| Tlcf Investments Limited | Financial services | 2014 |
| Tlsm Solutions Ltd | Information & communication | 2017 |
| Toby Wright Ltd. | Information & communication | 2011 |
| Tokenizescore Ltd | Information & communication | 2026 |
| TOM GT Transport Limited | Transport & logistics | 2018 |
| TOM Marks Heating and Bathroom Specialists Ltd | Administrative & support | 2012 |
| Topaz Bathrooms Limited | Construction | 2016 |
| Tora Couture Limited | Wholesale & retail | 2014 |
| Toro Sports Cars Ltd | Wholesale & retail | 2016 |
| Torre UK Limited | Wholesale & retail | 1994 |
| Toshiva Ltd | Wholesale & retail | 2025 |
| Total Business Solutions UK Limited | Professional & scientific | 1995 |
| Total Cost Consultancy Ltd | Professional & scientific | 2021 |
| Total Cover Plus (USA) Limited | Other services | 2014 |
| Touch of Thai 345 Ltd | Hospitality | 2025 |
| Tour-Ist Travel Ltd | Administrative & support | 2020 |
| Tower Growth Management LLP | | 2016 |
| TPA Sports Ltd | Arts & recreation | 2024 |
| Trac-Blu Ltd | Information & communication | 2024 |
| Tradepilotsolutions Ltd | Information & communication | 2026 |
| Traffic Control South West Limited | Construction | 2019 |
| Train EAT Gain Ltd. | Wholesale & retail | 2014 |
| Train to Win.Tv Limited | Professional & scientific | 2019 |
| Transac Sport Limited | Administrative & support | 2024 |
| Transmin Limited | Information & communication | 2021 |
| Traverse Media Ltd | Information & communication | 2018 |
| Trinity Construction Limited | Construction | 2015 |
| Trinity Transformation Ltd | Professional & scientific | 2023 |
| Trowbridge Advisory 21 Limited | Extraterritorial | 2021 |
| TRP7 Limited | Wholesale & retail | 2012 |
| TRU Rust Protection Limited | Wholesale & retail | 2025 |
| TRU Screed Limited | Construction | 2025 |
| Truecraft Construction Ltd | Construction | 2023 |
| Trupower Solutions Ltd | Construction | 2022 |
| Trustee Secretarial Services Limited | Professional & scientific | 2009 |
| TS Fruits & Vegetables Ltd | Wholesale & retail | 2026 |
| TSP Design and Build Ltd | Real estate | 2015 |
| TTL Networking Limited | Real estate | 2016 |
| Ttwcx.Com Limited | Professional & scientific | 2025 |
| Tudgey and Co Limited | Other services | 1943 |
| Turner Matthews Partnership Limited | Professional & scientific | 2000 |
| Turner Renovations Limited | Construction | 2017 |
| Turtle Tots Surrey Ltd | Education | 2021 |
| TVB Loan Management Limited | Financial services | 2012 |
| TW Residential Ltd | Construction | 2024 |
| Two Birds Catering Ltd | Hospitality | 2023 |
| Tyndall & Smallman Law Ltd | Professional & scientific | 2025 |
| UK Decorative Antiques Ltd | Other services | 2017 |
| UK Green Energy Installations Ltd | Construction | 2021 |
| UK VAC Services Ltd | Other services | 2011 |
| Ukrimvox. Ltd | Wholesale & retail | 2025 |
| Uktubelaser Ltd | Manufacturing | 2022 |
| Ulax Investments Limited | Construction | 2020 |
| Underfoot Flooring Solutions Limited | Administrative & support | 2008 |
| Underwood Football Consultancy Limited | Education | 2023 |
| Uni-Truths Ltd | Information & communication | 2018 |
| Uniq Inventive Limited | Information & communication | 2017 |
| Unique Garden Services Ltd | Administrative & support | 2023 |
| Unique Technical Solutions Limited | Construction | 2014 |
| Units 1-7 Aldermaston Management Co Limited | Real estate | 2015 |
| Unity Osteopathy Ltd | Health & social care | 2021 |
| Unlimited Equestrian Ltd | Administrative & support | 2026 |
| Unmasked Studio UK Ltd | Administrative & support | 2026 |
| Updolli Ltd | Professional & scientific | 2021 |
| Upper Hound Limited | Other services | 2018 |
| Upper Hound Training Limited | Education | 2022 |
| Upside Down Aerial Fitness Limited | Arts & recreation | 2019 |
| Uptown Tiger Ltd | Real estate | 2017 |
| Urban Folklore Ltd | Information & communication | 2024 |
| Urban Upgrade Online Ltd | Wholesale & retail | 2025 |
| US5 Collective Ltd | Information & communication | 2025 |
| V&R 1 LLP | | 2021 |
| V&R Limited | Financial services | 2021 |
| V2D.AI Limited | Information & communication | 2025 |
| Valbro Scaffolding Ltd | Construction | 2011 |