| Third Ancells (Fleet) Management Company Limited | Households | 1991 |
| Third Weybrook Residents Association (Guildford) Limited | Households | 1989 |
| THJ Investments Limited | Real estate | 2020 |
| THL Media Ltd | Administrative & support | 2019 |
| Thomas Sopwith Aviation Company Limited | Extraterritorial | 1996 |
| Thomoli Holdings Limited | Households | 2020 |
| Thorgills Property Group Limited | Extraterritorial | 2008 |
| Thornfield Hawley Management Company Limited | Households | 1985 |
| Thornton Developments Limited | Construction | 1986 |
| Thornton Homes Limited | Construction | 1976 |
| Three Counties Property Services Limited | Real estate | 2012 |
| Three Sixty Cleaning Services Limited | Administrative & support | 2022 |
| Three Sixty Maintenance Limited | Extraterritorial | 2019 |
| Threshold Infrastructure Ltd | Construction | 2020 |
| Throne Innovation Ltd | Manufacturing | 2025 |
| Through the Blue Ltd | Arts & recreation | 2025 |
| Thru Europe Limited | Professional & scientific | 2007 |
| Tiami Limited | Professional & scientific | 2016 |
| Tida O Limited | Professional & scientific | 2016 |
| Tilney Land Holdings Ltd | Households | 2019 |
| Tilney Property Limited | Real estate | 2015 |
| TIM Sherston Property Search Limited | Real estate | 2019 |
| TIM Woodward Publishing Limited | Information & communication | 1984 |
| Timeframe Clocks Limited | Manufacturing | 2024 |
| Tina's Minimarket Limited | Other services | 2021 |
| Tipsy Knight Ltd | Hospitality | 2026 |
| Tiptop Building & Design Ltd | Construction | 2014 |
| Tirien Partners Ltd | Information & communication | 2021 |
| Titan Firework Displays Ltd | Arts & recreation | 2025 |
| TJW Contract Solutions Limited | Administrative & support | 2011 |
| TJW Corporate Services Limited | Professional & scientific | 2015 |
| TJW Property Holdings Limited | Real estate | 2023 |
| Tjwph Limited | Real estate | 2017 |
| Tkar Ltd | Professional & scientific | 2009 |
| TL Corporate Limited | Other services | 2013 |
| TLC Entertainment Ltd | Hospitality | 2019 |
| Tlsk Solicitors Limited | Professional & scientific | 2015 |
| TM Joint Solutions Ltd | Health & social care | 2013 |
| TM Roofing & Building Limited | Construction | 2023 |
| TM Stop N Shop Express GB Ltd | Wholesale & retail | 2021 |
| TMB International Logistics Limited | Transport & logistics | 2023 |
| TMH Partners Simply Savings LLP | | 2023 |
| TMS Solutions Ltd | Transport & logistics | 2025 |
| Toast & EGG Ltd | Real estate | 2025 |
| Toffee Dating Ltd | Information & communication | 2017 |
| Together in Sport Limited | Education | 2022 |
| TOM Commerce Limited | Wholesale & retail | 2021 |
| TOM Hampton Recruitment Limited | Administrative & support | 2023 |
| Tomo Transport Ltd | Transport & logistics | 2021 |
| Tonik Building Ltd | Construction | 2019 |
| Tony Peacock Homes Limited | Real estate | 1984 |
| Top Banana Consulting Ltd | Professional & scientific | 2024 |
| Top Banana Holdings Ltd | Financial services | 2024 |
| Top Banana Property Ltd | Real estate | 2024 |
| Top Business Group Limited | Professional & scientific | 2023 |
| Top FD Ltd | Professional & scientific | 2019 |
| Top Marks Cleaning Ltd | Administrative & support | 2023 |
| Top Notch Kitchen and Bedrooms Ltd | Construction | 2023 |
| Top Performance Services 2011 Limited | Wholesale & retail | 2011 |
| Top Story Ltd | Education | 2022 |
| Topflight Innovations Ltd | Professional & scientific | 2026 |
| Topform Scaffolding Limited | Construction | 2026 |
| Tordoff Associates Ltd | Professional & scientific | 2012 |
| Toropro Ltd | Wholesale & retail | 2014 |
| Tortue Limited | Wholesale & retail | 2022 |
| Tortuga Tattoo Company Ltd | Other services | 2018 |
| Total Business Support Ltd | Administrative & support | 2025 |
| Total Digital Entertainment Ltd | Professional & scientific | 2023 |
| Totally Land Limited | Real estate | 2010 |
| Totally Welsh (Holdings) Limited | Financial services | 2024 |
| Totally Welsh Limited | Manufacturing | 1999 |
| Totem Marketing Ltd | Professional & scientific | 2012 |
| Touchtap Ltd | Information & communication | 2022 |
| Tower Farm Developments Ltd | Construction | 2023 |
| Tower Farm Homes Limited | Construction | 2022 |
| Town & Country (Holdings) Limited | Extraterritorial | 1997 |
| Town Barbers Limited | Other services | 2013 |
| Townends (Financial Services) Limited | Financial services | 1996 |
| Townends (Residential Sales) Limited | Real estate | 1995 |
| Townside Real Estate Ltd | Construction | 2018 |
| Towry Thompson Limited | Administrative & support | 2011 |
| TP Primier Ltd | Wholesale & retail | 2025 |
| TR Black TIE Transport Ltd | Transport & logistics | 2019 |
| Tradec Supplies Limited | Wholesale & retail | 2010 |
| Traditionally Modern Limited | Manufacturing | 2022 |
| Training and Security Resources Ltd. | Administrative & support | 2016 |
| Training Enhancing Performing Ltd | Education | 2021 |
| Trans 3000 Limited | Transport & logistics | 2022 |
| Trans 4000 Limited | Transport & logistics | 2022 |
| Trans 5000 Limited | Transport & logistics | 2022 |
| Trans Universal Logistics Limited | Transport & logistics | 2011 |
| Transform Consultancy Solutions Ltd | Information & communication | 2006 |
| Transformable Limited | Professional & scientific | 2021 |
| Transformation Consulting Limited | Information & communication | 2014 |
| Transrkb Haulage Ltd | Transport & logistics | 2016 |
| Travel Specialist Consultancy Limited | Professional & scientific | 2014 |
| Travers Corn Barns Limited | Construction | 2020 |
| Travers Corn Barns Management Company Limited | Households | 2022 |
| Travis Paving Ltd | Administrative & support | 2023 |
| Traynor Building Services Limited | Construction | 1988 |