| Thwaites Construction Ltd | Construction | 2025 |
| Tiberos Limited | Information & communication | 2020 |
| TIC Hodge Limited | Other services | 2013 |
| Ticks Haulage Limited | Transport & logistics | 2003 |
| Tiffin Kitchen Ltd | Hospitality | 2024 |
| Tigerus Garden Design Ltd | Professional & scientific | 2023 |
| Tikadi Limited | Other services | 2007 |
| Tingles by Victoria Ltd | Hospitality | 2020 |
| TJ Turner Automotive Limited | Professional & scientific | 2014 |
| TJC Communications Limited | Wholesale & retail | 2018 |
| Tknm Ltd | Health & social care | 2018 |
| TKS Protech Limited | Wholesale & retail | 2003 |
| TL Mobile Thread Repairs Ltd | Wholesale & retail | 2020 |
| TL Property Solutions Ltd | Construction | 2021 |
| TMB Group Ltd | Financial services | 2025 |
| Tmbcoin.Gold Ltd | Financial services | 2025 |
| TMC Flooring Limited | Construction | 2009 |
| TMM Contracts Ltd | Construction | 2017 |
| Tobsoft Ltd | Information & communication | 2026 |
| Tobynat Limited | Real estate | 2018 |
| Tobynat Properties Limited | Real estate | 2025 |
| Toddle Town Ltd | Arts & recreation | 2024 |
| Toffee Vodka Tours (TVT) Limited | Hospitality | 2017 |
| Tofts Property Company Ltd | Real estate | 2025 |
| Together WE Excel Limited | Professional & scientific | 2026 |
| Tokay Property Limited | Real estate | 2012 |
| Tolstac Holdings Limited | Financial services | 2025 |
| TOM & Tandy Transport Limited | Transport & logistics | 2005 |
| Tomas Ltd | Construction | 2014 |
| Tomos Tavern Limited | Hospitality | 2013 |
| Top Physio Healthcare Limited | Health & social care | 2010 |
| Top-Tier Services Limited | Professional & scientific | 2018 |
| Total Lockout (Safety) Limited | Wholesale & retail | 2010 |
| Total Plastering Limited | Construction | 2024 |
| Total Service Group Limited | Financial services | 2025 |
| Total Supplies Direct Ltd | Wholesale & retail | 2025 |
| Toucan Events Ltd | Arts & recreation | 2023 |
| Tourang Limited | Professional & scientific | 2021 |
| Tower Upholstery Limited | Other services | 2006 |
| Towerlands Estate Management Company Limited | Real estate | 2022 |
| TP Aesthetics Limited | Health & social care | 2015 |
| TP Carpentry and Construction Ltd | Manufacturing | 2024 |
| TPC Essex Ltd | Arts & recreation | 2025 |
| TPM Medical Training & Events Services Ltd | Transport & logistics | 2013 |
| TPS Site Logistics Ltd | Professional & scientific | 2013 |
| Track Engineering Construction Services Limited | Construction | 2015 |
| Tran-Quili Ltd | Wholesale & retail | 2025 |
| Transcom Engineering Services Limited | Professional & scientific | 2012 |
| Trials Equipment (UK) Ltd | Administrative & support | 2001 |
| Triangle INK Limited | Manufacturing | 2009 |
| Tribesmen Consulting Limited | Professional & scientific | 2024 |
| Tribeworks Limited | Construction | 2009 |
| Tricad Ltd. | Professional & scientific | 1996 |
| Trickster Ltd | Information & communication | 1997 |
| Triconnex Ltd | Construction | 2010 |
| Trident Truck and Equipment Ltd | Wholesale & retail | 2024 |
| Trim Tech (London) Ltd | Wholesale & retail | 2017 |
| Trimco Group (UK) Limited | Manufacturing | 1985 |
| Trimco Group Holdings (UK) Limited | Manufacturing | 2004 |
| Triplex Distribution Limited | Wholesale & retail | 2011 |
| Triplezee Consulting Ltd | Professional & scientific | 2021 |
| Tripple V Limited | Professional & scientific | 2021 |
| Triunity.Movie Ltd | Information & communication | 2025 |
| Trizz Ltd | Professional & scientific | 2024 |
| Tropical Market Ltd | Wholesale & retail | 2025 |
| Troubleshooter Limited | Professional & scientific | 2007 |
| Trudstar Limited | Health & social care | 2019 |
| Trugo Freight Services Ltd | Transport & logistics | 2021 |
| Tsang Investments Limited | Real estate | 2017 |
| TTA Enterprises Limited | Construction | 2018 |
| Ttje Limited | Information & communication | 2024 |
| TTM Partnership LLP | | 2008 |
| Tu-Be-Ze-Me Ltd | Real estate | 2024 |
| Tudor 1550 Ltd | Real estate | 2019 |
| Tudor Summer Ltd | Hospitality | 2022 |
| Tudor Two Ltd | Hospitality | 2023 |
| Tunfield Flats Residents Association Limited | Households | 1973 |
| Turbopool Limited | Construction | 1983 |
| Turner & Lambert Limited | Other services | 2014 |
| Turner Rise Investments Limited | Real estate | 2025 |
| Turners Plumbing & Heating Solutions Limited | Construction | 2013 |
| Tutoring Solutions Tailormade Limited | Education | 2023 |
| Twelve Braintree Management Company Limited | Administrative & support | 2009 |
| Twentyone Performance Limited | Arts & recreation | 2019 |
| Twisted Envy Ltd | Other services | 2022 |
| Two and the Swan Ltd | Hospitality | 2025 |
| TXE Africa Ltd | Information & communication | 2024 |
| TY OG Ventures Limited | Wholesale & retail | 2025 |
| Tyce Limited | Extraterritorial | 2017 |
| Typhon Enterprises Ltd | Professional & scientific | 2016 |
| U.K. Mobile Installations Ltd | Wholesale & retail | 2019 |
| U.K. Tapes Ltd | Manufacturing | 1996 |
| UB Corporation Limited | Transport & logistics | 2020 |
| Uber Holdings Limited | Financial services | 2015 |
| Uber-Skor Limited | Administrative & support | 2023 |
| UK Brick Slips Ltd | Wholesale & retail | 2026 |
| UK PC Limited | Professional & scientific | 2000 |
| UK Staging and Access Solutions Ltd | Manufacturing | 2019 |
| UK Watercourse & Fisheries Ltd | Agriculture & fishing | 2026 |
| Ukdatasecure Ltd | Professional & scientific | 2009 |