| Total Services Building Ltd | Professional & scientific | 2020 |
| Total Value Consultancy Limited | Professional & scientific | 2002 |
| Tots Crops Franchise Limited | Administrative & support | 2012 |
| Touchstone Geological Services Limited | Mining & quarrying | 2018 |
| Touchwood Crafts Limited | Manufacturing | 2015 |
| Tourtop Travel Limited | Administrative & support | 2023 |
| Tovalco Ltd | Professional & scientific | 2007 |
| TOW2GO Ltd | Transport & logistics | 2024 |
| Town & Country Windows (Swindon) Limited | Manufacturing | 1989 |
| Town Hall Catering Limited | Hospitality | 2025 |
| Towpath Gardens RTM Company Ltd | Households | 2020 |
| Toybox Day Nursery (Bristol) Limited | Education | 2010 |
| TP Tiling Ltd | Construction | 2022 |
| Tpec Ltd | Hospitality | 2026 |
| TQ Music Limited | Information & communication | 2011 |
| TQ Structix Limited | Construction | 2025 |
| TR Automotive Limited | Wholesale & retail | 2021 |
| Traalk Logistics Ltd | Transport & logistics | 2024 |
| Traction Automotive Ltd | Information & communication | 2026 |
| Trade Smart Building Plastics Ltd | Wholesale & retail | 2022 |
| Tradecarco Limited | Wholesale & retail | 2026 |
| Trademarket Management M.K Ltd | Wholesale & retail | 2021 |
| Traderoute Limited | Professional & scientific | 2016 |
| Trades Smart Ltd | Wholesale & retail | 2012 |
| Tradewisenet Academy PVT. Ltd | Other services | 2025 |
| Tradsol Limited | Wholesale & retail | 2002 |
| Trailer Commercial Services Ltd | Wholesale & retail | 2026 |
| Trailer Stage Services Limited | Wholesale & retail | 2016 |
| Trainerpool Limited | Professional & scientific | 2005 |
| Training Intelligence (TIQ) Ltd | Information & communication | 2023 |
| Trak Employment Solutions (Gloucester) Ltd | Administrative & support | 2022 |
| Trak Employment Solutions Ltd | Administrative & support | 2007 |
| Trak Investments Ltd | Real estate | 2018 |
| Trak Professional & Executive Ltd | Administrative & support | 2023 |
| Trak Property Services Ltd | Administrative & support | 2018 |
| Trak Solutions Group Limited | Financial services | 2018 |
| Tram Southwest Ltd | Real estate | 2021 |
| Trans FB Ltd | Transport & logistics | 2019 |
| Trans XL International Limited | Wholesale & retail | 1974 |
| Transcd Limited | Hospitality | 2025 |
| Transenemi Ltd | Transport & logistics | 2024 |
| Transforming Training Teams Ltd | Professional & scientific | 2025 |
| Transin Logistics Ltd | Wholesale & retail | 2026 |
| Transition Trees Limited | Administrative & support | 2016 |
| Transport.Rone Ltd | Transport & logistics | 2015 |
| Transported Ltd | Hospitality | 2018 |
| Transxl Holdings Limited | Financial services | 2018 |
| Transylvania Land Surveying Limited | Construction | 2021 |
| Tratos Cavi UK Ltd. | Manufacturing | 2000 |
| Trauma Informed Ltd | Health & social care | 2017 |
| Travax Limited | Information & communication | 2026 |
| Travellers Nest Estates Ltd | Real estate | 2023 |
| Travellers Nest Ltd | Real estate | 2021 |
| Trbarrett Consulting Ltd | Professional & scientific | 2025 |
| TRC (Swindon) Limited | Transport & logistics | 2009 |
| TRC Building Services Ltd | Construction | 2025 |
| Treasure Mine Collections, UK Ltd | Wholesale & retail | 2014 |
| Treasuree Limited | Financial services | 2026 |
| Treatment Rooms (South) Ltd | Other services | 2022 |
| Tree Keeper Books Ltd | Information & communication | 2024 |
| Tree Meta Systems Limited | Extraterritorial | 2013 |
| Tree Tents International Limited | Construction | 2016 |
| Treetops Communications Limited | Information & communication | 2001 |
| Tremaine Studio Limited | Professional & scientific | 2021 |
| Trend Technologies Limited | Information & communication | 2020 |
| Trenic TKD and Fitness Centre (Casc) | Arts & recreation | 2012 |
| Trent Road RTM Company Ltd | Households | 2015 |
| Trevelyn Limited | Information & communication | 2012 |
| Trevor Hunt Accountancy Limited | Professional & scientific | 2002 |
| Tri-Ed and Tested Limited | Professional & scientific | 2020 |
| Tribe Hair Studio Ltd | Other services | 2020 |
| TRICORN4 International Ltd | Wholesale & retail | 2013 |
| Trident South West Limited | Administrative & support | 2015 |
| Trifare Limited | Hospitality | 2020 |
| Trigon Consulting Limited | Information & communication | 2022 |
| Trilogic Recruitment Ltd | Administrative & support | 2020 |
| Trimac Investments Limited | Real estate | 1984 |
| Trimac Properties Limited | Real estate | 1987 |
| Tring Martial Arts Academy LLP | | 2013 |
| Trinity House SPV Ltd | Real estate | 2024 |
| Trinity Kind Cares Ltd | Health & social care | 2018 |
| TRINKETS3D Ltd | Wholesale & retail | 2025 |
| Trio Advisory & Accountancy Ltd | Professional & scientific | 2026 |
| Triple Jump Limited | Real estate | 2026 |
| Trishaan 3D Prints Limited | Wholesale & retail | 2026 |
| Tristat Office Supplies Limited | | 1989 |
| Triton Knoll Holdco Limited | Financial services | 2018 |
| Triton Knoll Offshore Wind Farm Limited | Energy | 1999 |
| Triton Motors Ltd | Wholesale & retail | 2025 |
| Triumph International Limited | Wholesale & retail | 1954 |
| Triumphant Covenant Care Ltd | Health & social care | 2023 |
| Triumphant Covenant Security Ltd | Administrative & support | 2023 |
| Trojan Stonework Limited | Construction | 2013 |
| Troka Group Limited | Financial services | 2022 |
| Trolley Maintenance Services Limited | Other services | 2002 |
| Trolley Sales and Service Limited | Other services | 2010 |
| Tropi Bites Ltd | Wholesale & retail | 2025 |
| Trowbridge Town Car Wash Ltd | Administrative & support | 2026 |
| Troy Computer Software Limited | Information & communication | 1992 |
| Troysoft Limited | Information & communication | 2005 |