| Tradeforce Facilities Management Limited | Construction | 2024 |
| Trades Cosmos Limited | Wholesale & retail | 2021 |
| Trades UK 247 Group Ltd | Construction | 2024 |
| Tradestech Limited | Financial services | 2015 |
| Trading Standards International Ltd | Administrative & support | 2009 |
| Trading-Ds Ltd | Construction | 2023 |
| Traditii Muntenesti Ltd | Wholesale & retail | 2019 |
| Traditional Castings (Fibrous) Plastering Limited | Construction | 2007 |
| Traffic Solutions Traffic Management Limited | Construction | 2019 |
| Tragab Ltd | Transport & logistics | 2021 |
| Train Maintenance Limited | Manufacturing | 2025 |
| Tranquil Therapy Ltd | Health & social care | 2024 |
| Tranquillity in Glass Ltd | Construction | 2009 |
| Trans AID UK Limited | Wholesale & retail | 2009 |
| Trans Metal Ltd | Water & waste | 2020 |
| Trans World Shipping (T.W.S.) Limited | Transport & logistics | 2002 |
| Transcendental Technology Limited | Information & communication | 2014 |
| TRANSFORM8 Ltd | Arts & recreation | 2019 |
| Transilvania Construct Ltd | Construction | 2013 |
| Transmits Hope Limited | Manufacturing | 2008 |
| Transport Alexa Ltd | Transport & logistics | 2020 |
| Transport Hoisa Logistic Ltd | Transport & logistics | 2025 |
| Transportes DO Valado UK Limited | Transport & logistics | 2021 |
| Transylvania Transport Ltd | Transport & logistics | 2022 |
| Traste Developments Limited | Real estate | 2004 |
| Travel Junky London Ltd | Administrative & support | 2025 |
| Trdg Carpentry Ltd | Construction | 2025 |
| Trdg Construction Ltd | Construction | 2019 |
| Treadcore Ltd | Construction | 2025 |
| Treasure Vince Limited | Health & social care | 2015 |
| Tredrock Ltd | Professional & scientific | 2024 |
| Trend City Ltd | Wholesale & retail | 2015 |
| Trending Essential Picks Ltd | Wholesale & retail | 2025 |
| Tres Energy Limited | Construction | 2019 |
| Trevor Oliver Production Services Ltd | Transport & logistics | 2020 |
| Trevor Ultimate Store Limited | Wholesale & retail | 2024 |
| Tribal Kingdom Construction Ltd | Construction | 2018 |
| Trident Ductwork Ltd | Construction | 2018 |
| Trident-Shipping Limited | Extraterritorial | 1988 |
| Tridev Logistics Ltd | Transport & logistics | 2025 |
| Triffick Trucking Ltd | Transport & logistics | 2019 |
| Trimmings Limited | Wholesale & retail | 2017 |
| Trinero Ltd | Manufacturing | 2023 |
| Trio Maintenance Ltd | Construction | 2017 |
| Triotech Recruitment Ltd | Administrative & support | 2017 |
| Triple Aces (Pugs & Bullys) Ltd | Agriculture & fishing | 2018 |
| Triple D Trader Limited | Administrative & support | 2019 |
| Triple Guard Scaffolding Limited | Construction | 2019 |
| Triple Horizons Limited | Real estate | 2016 |
| Triple J Holdings Ltd | Real estate | 2025 |
| Triple JO Ltd | Education | 2011 |
| Triple L Training & Medical Limited | Health & social care | 2015 |
| Tripleblue Developments Limited | Construction | 2001 |
| Triumph Thermal Services Ltd | Construction | 2023 |
| Trofi SD Limited | Transport & logistics | 2011 |
| Troperties Limited | Real estate | 2021 |
| Tropicool Climate Control Limited | Construction | 2008 |
| Truckstars Technology Ltd | Information & communication | 2022 |
| True Aspire Ltd | Wholesale & retail | 2026 |
| True Vehicle Sales Limited | Wholesale & retail | 2016 |
| Trueasset Insight Ltd | Information & communication | 2025 |
| Truebridge Solutions Ltd | Education | 2025 |
| Trust Design Studio Ltd | Professional & scientific | 2025 |
| Trust Sheq Solutions Ltd | Other services | 2025 |
| Truvue Exterior Cleaning Ltd | Administrative & support | 2026 |
| Trwc Leisure Ltd | Wholesale & retail | 2026 |
| TS Business Consulting Services Limited | Information & communication | 2012 |
| TS Plumbing (Essex) Limited | Construction | 2013 |
| TSC Construction Services Ltd | Construction | 2026 |
| TSE (IT) Services Limited | Information & communication | 2002 |
| Ttba Consulting Limited | Transport & logistics | 2016 |
| Ttdor Limited | Transport & logistics | 2024 |
| TTM Technology Limited | Information & communication | 2023 |
| Ttmp Ltd | Construction | 2007 |
| TTS Forwarding Limited | Transport & logistics | 2026 |
| TTT Transport & Logistics Ltd | Transport & logistics | 2024 |
| Tubular Tech Limited | Construction | 2015 |
| Tudor Court Residents Association (Noak Bridge) Limited | Households | 1984 |
| Tudor Crinu Limited | Wholesale & retail | 2025 |
| Tudor Ridge Electrical Services Ltd | Construction | 2019 |
| Tudor Surveying Limited | Construction | 2020 |
| Tudormay Facades Ltd | Construction | 2022 |
| Tudormay Fireproofing Ltd | Construction | 2019 |
| Tudormay Ltd | Construction | 2004 |
| Tugba Home Trade Limited | Wholesale & retail | 2024 |
| Tunjina Hajj and Umrah Expert UK Ltd | Administrative & support | 2023 |
| Tunnelcraft Holdings Limited | Construction | 2021 |
| Tunnelcraft Labour Services LLP | | 2018 |
| Tunnelcraft Limited | Construction | 1992 |
| Turner Whittman Digital Services Limited | Information & communication | 2006 |
| Turner-Whittman Logistics Ltd | Transport & logistics | 2021 |
| Turner-Whittman Properties Ltd | Real estate | 2020 |
| Turners Florists Ltd | Wholesale & retail | 2019 |
| Tusha Transport Ltd | Wholesale & retail | 2023 |
| Tuskite Property Management Ltd | Real estate | 2010 |
| Tutu's Kitchen Ltd | Hospitality | 2026 |
| TVP Property Ltd | Real estate | 2018 |
| TVR Pipefitting Limited | Construction | 2019 |
| TW Flooring Limited | Construction | 2018 |
| Twelve Jewels Limited | Construction | 2023 |