| Tide Resources Limited | Information & communication | 2021 |
| Tiffany’S Home Ltd | Real estate | 2022 |
| Tikka Xpress Ltd | Hospitality | 2024 |
| Tiles of Wisdom Limited | Wholesale & retail | 2015 |
| TIM Cassidy Holdings Limited | Financial services | 2025 |
| Timberline Partners LLP | | 2012 |
| Timberstore Preservation Ltd | Manufacturing | 2008 |
| Time for YOU South Bucks Ltd | Other services | 2026 |
| Tintern Property Services Limited | Other services | 2007 |
| Tiny Wealth Limited | Real estate | 2013 |
| Titan Tippers Ltd | Transport & logistics | 2020 |
| Titanic 2020 Ltd | Public administration | 2020 |
| Titanium Roots Limited | Health & social care | 2026 |
| Tixel UK Limited | Administrative & support | 2021 |
| TJP Surgical Limited | Health & social care | 2026 |
| TLG Group Holdings Limited | Administrative & support | 2025 |
| TLG Infrastructure Limited | Administrative & support | 2011 |
| TLG PAY Limited | Administrative & support | 2023 |
| TMT Investments Limited | Administrative & support | 2017 |
| Tnovations Limited | Wholesale & retail | 2023 |
| Tockington Properties Limited | Real estate | 1978 |
| TOM Jones Marina Limited | Extraterritorial | 1964 |
| Tomato Drainage Limited | Extraterritorial | 2016 |
| Tomato Plant Limited | Transport & logistics | 2017 |
| Tomato Plant Properties Limited | Real estate | 2011 |
| Tomato Plumbing Limited | Extraterritorial | 2016 |
| Tomato Towing Limited | Extraterritorial | 2016 |
| Tomato Tyres Limited | Wholesale & retail | 2014 |
| Toni Events Ltd | Professional & scientific | 2020 |
| Tony Cowling Foundation CIC | Education | 2020 |
| Topstitles Limited | Information & communication | 2019 |
| Topstorm Limited | Hospitality | 2019 |
| Torbes Limited | Professional & scientific | 2019 |
| Torix Managed Services Limited | Information & communication | 2009 |
| TOS Bars (Beaconsfield) Ltd | Hospitality | 2024 |
| Total Drain Care Investments Limited | Construction | 2012 |
| Total Pest Control Ltd | Administrative & support | 2018 |
| Totternhoe Holdings Limited | Professional & scientific | 2011 |
| Totternhoe Metal Recycling Limited | Water & waste | 2011 |
| Toucanterra Ltd | Wholesale & retail | 2025 |
| Towards Meaning Ltd | Health & social care | 2023 |
| Tpet Associates Ltd | Professional & scientific | 2025 |
| Tracemount Properties Limited | Real estate | 1987 |
| Trade Carpet Company Limited | Administrative & support | 2007 |
| Trade Mark Projects Limited | Professional & scientific | 2016 |
| Trading and Beyond Ltd | Financial services | 2021 |
| Trafalgar Vehicle Services Limited | Administrative & support | 2010 |
| Transformability Limited | Professional & scientific | 2010 |
| Treble Property Management Limited | Real estate | 2024 |
| Trendstar (LB) Limited | Financial services | 2020 |
| Treslan Limited | Real estate | 2001 |
| TRI Overseas Limited | Administrative & support | 2011 |
| Triad Care Limited | Administrative & support | 2024 |
| Tribe Culture Change Holdings Limited | Professional & scientific | 2024 |
| Tribe Culture Change Limited | Professional & scientific | 2016 |
| Trinity (Slough) Management Company Limited | Households | 2017 |
| Trinity Heights Ltd | Professional & scientific | 2025 |
| Trinity Property Solutions Ltd | Administrative & support | 2016 |
| True Scale Carbon Limited | Professional & scientific | 2024 |
| Trusty Central Limited | Professional & scientific | 2013 |
| Truth and Dare Group Ltd | Administrative & support | 2024 |
| Tscl Investments Limited | Financial services | 2022 |
| TSL Data Centre Solutions Ltd | Information & communication | 2019 |
| Tuggen Holdings Ltd | Financial services | 2023 |
| Turftonics Ltd | Administrative & support | 2017 |
| Turney Brothers (Builders) and Company Limited | Construction | 1956 |
| Tusk Cleaning Ltd | Professional & scientific | 2016 |
| Tweedpark Limited | Professional & scientific | 2010 |
| TWINSTAR4HIRE Ltd | Transport & logistics | 2019 |
| Twsolutionsltd Ltd | Wholesale & retail | 2026 |
| Twyford Van Hire Limited | Administrative & support | 2005 |
| Txtv Limited | Information & communication | 2006 |
| Tyche Leadership Consulting Limited | Administrative & support | 2011 |
| Tyfoon Restaurants Limited | Professional & scientific | 2016 |
| Tyrion Construction and Development Company Limited | Construction | 2022 |
| U Energy Ltd | Energy | 2021 |
| U Micro Grid Ltd | Manufacturing | 2021 |
| Ubuk Limited | Wholesale & retail | 2025 |
| Ugames Software Limited | Information & communication | 2021 |
| UK Roofing Group Ltd | Construction | 2026 |
| UK Time's UP | Other services | 2018 |
| Ukidc Group Limited | Construction | 2025 |
| Ultralight UK Limited | Administrative & support | 2009 |
| Unaterra Consult Limited | Professional & scientific | 2014 |
| Unicorn Ventures (London) Limited | Professional & scientific | 2014 |
| Unicrop Holdings Limited | Real estate | 1950 |
| Unitcastle Limited | Extraterritorial | 1984 |
| United Open MRI Limited | Health & social care | 2002 |
| Unlocking Your Potential Ltd | Information & communication | 2023 |
| Unsworth Consulting Group Ltd | Professional & scientific | 2021 |
| Upside Down World Limited | Professional & scientific | 2022 |
| Upton Investments Ltd | Construction | 2019 |
| Urban Fine Art Limited | Hospitality | 2015 |
| Urban Front Ltd. | Manufacturing | 2002 |
| Useful Ventures Limited | Professional & scientific | 2009 |
| USF International Limited | Administrative & support | 2015 |
| V1000 Limited | Information & communication | 2016 |
| V3 Property Developers Limited | Construction | 2025 |
| Valde Consulting Limited | Professional & scientific | 2007 |
| Valet Parking Limited | Real estate | 1988 |