| Transit Holdco Limited | Financial services | 2023 |
| Transit Midco Limited | Financial services | 2023 |
| Transit Topco Limited | Financial services | 2023 |
| Translation Network Limited | Professional & scientific | 2017 |
| Transmagic Limited | Transport & logistics | 2015 |
| Transparent Recruitment Ltd | Transport & logistics | 2023 |
| Transport 05 Limited | Transport & logistics | 2024 |
| Transport 22 Limited | Transport & logistics | 2024 |
| Transport 247 Ltd | Transport & logistics | 2018 |
| Transport 44 Ltd | Transport & logistics | 2015 |
| Transraf Limited | Transport & logistics | 2012 |
| Tranzit Executive Ltd | Transport & logistics | 2026 |
| Travel A2B Limited | Transport & logistics | 2021 |
| Travel Base Limited | Administrative & support | 2010 |
| Travel Style (UK) Limited | Administrative & support | 2003 |
| Travelline Transfers Ltd | Transport & logistics | 2025 |
| Travelong Hospitality Limited | Wholesale & retail | 2019 |
| Travelopedia Ltd | Administrative & support | 2012 |
| Travelport Corporate Finance Ltd | Financial services | 2018 |
| Travelport International Investments Ltd. | Financial services | 2023 |
| Travelsoft PAY UK Limited | Financial services | 2025 |
| Travelsoft UK Holding Limited | Financial services | 2024 |
| Travolution Limited | Administrative & support | 2025 |
| Traynor Rail Services Limited | Other services | 2019 |
| TRB Effects Ltd | Health & social care | 2016 |
| Treadstone Solutions Ltd | Professional & scientific | 2018 |
| Treats and Tales Limited | Wholesale & retail | 2025 |
| Treatz Franchising Ltd | Hospitality | 2013 |
| Treatz Watford Ltd | Wholesale & retail | 2025 |
| Treatz WD Ltd | Hospitality | 2025 |
| Treatz West Ltd | Hospitality | 2025 |
| Trebor Packaging Systems Limited | | 1987 |
| Trecity Ltd | Information & communication | 2026 |
| Tredeurs Limited | Real estate | 2024 |
| Treelin Property Limited | Real estate | 2016 |
| Trees a Crowd Tree Services Limited | Other services | 2024 |
| Treetop Landscape (Berkshire) Ltd | Administrative & support | 2022 |
| Treetops Landscapes Limited | Administrative & support | 1995 |
| Trelawney Parade Limited | Real estate | 2025 |
| Trelica Limited | Information & communication | 2017 |
| Trenac Estates Limited | Construction | 2006 |
| Trend BI Ltd | Information & communication | 2018 |
| Trend Full Ltd | Wholesale & retail | 2022 |
| Trend Holding UK Ltd | Real estate | 2022 |
| Trendbuild Innovations Ltd | Real estate | 2024 |
| Trender Social Ltd | Professional & scientific | 2022 |
| Trendocart Limited | Wholesale & retail | 2024 |
| Trendora E-Commerce Ltd | Construction | 2025 |
| Trendsetters 360 Ltd | Wholesale & retail | 2024 |
| Trendy Goods Emporium Ltd | Wholesale & retail | 2024 |
| Trendycatportraits Ltd | Arts & recreation | 2018 |
| Trendzi Ltd | Wholesale & retail | 2025 |
| Trent Motors Ltd | Wholesale & retail | 2025 |
| Trent Villas Limited | Households | 2018 |
| Trevion Service Ltd | Construction | 2026 |
| Trexa Construction Ltd | Construction | 2026 |
| TRI Management Limited | Construction | 2000 |
| Triad Enterprises Limited | Professional & scientific | 2013 |
| Triark Pumps Limited | Manufacturing | 1984 |
| Tribe Platforms Ltd | Information & communication | 2025 |
| Trident Equities Ltd | Financial services | 2024 |
| Trident Healthcare Ltd | Health & social care | 2017 |
| Trident Sarl Limited | Real estate | 2023 |
| Trident Stunts Limited | Arts & recreation | 2019 |
| Trident Transport Ltd | Transport & logistics | 2025 |
| Trident Wealth Management Ltd | Financial services | 2013 |
| Tridiva IT Solutions Limited | Information & communication | 2014 |
| Triforce Ventures Limited | Financial services | 2025 |
| Trigen Software Solutions Ltd | Information & communication | 2013 |
| Trigun Ltd | Construction | 2026 |
| Trijal Real Estate Limited | Real estate | 2024 |
| Trik Engineering Ltd | Professional & scientific | 2010 |
| Trillion Air Limited | Transport & logistics | 2023 |
| Trilogy Care Ltd | Education | 2019 |
| Trilye Shop Ltd | Wholesale & retail | 2024 |
| Trimount Residential Isle of Wight Limited | Real estate | 2006 |
| Trinetra Tech Ltd | Information & communication | 2025 |
| Trinidad Services Limited | Administrative & support | 2020 |
| Trinity Investment Group Limited | Wholesale & retail | 2021 |
| Trio Building Solutions Limited | Administrative & support | 2010 |
| Trio City Limited | Hospitality | 2024 |
| Trio Engineering UK Ltd | Construction | 2015 |
| Triple "a" Developments (Slough) Limited | Construction | 1988 |
| Triple a Developments (Trading) Limited | Wholesale & retail | 2005 |
| Triple a Developments Management Limited | Real estate | 1996 |
| Triple a Holdings Limited | Professional & scientific | 1999 |
| Triple Ace Executive Cars Ltd | Transport & logistics | 2018 |
| Triple Ace Group Ltd | Wholesale & retail | 2024 |
| Triple SR C.I.C. | Other services | 2022 |
| Triple-S Construction Ltd | Construction | 2016 |
| Tripple AAA Catering Ltd | Hospitality | 2025 |
| Tripple Sea Limited | Other services | 2024 |
| Triquant Investments Ltd | Financial services | 2018 |
| Trisec HO Limited | Professional & scientific | 2025 |
| Trisec PAY Limited | Professional & scientific | 2025 |
| Trishula Ltd | Professional & scientific | 2024 |
| Tristar Logistics Ltd | Transport & logistics | 2020 |
| Tristar Support Services Ltd | Administrative & support | 2023 |
| Triunity Properties Limited | Real estate | 2024 |
| Trivedi Corporation Ltd | Wholesale & retail | 2021 |