| TOM Mueck Foundation | Information & communication | 2021 |
| Tomlin Taylor Surveying Ltd | Construction | 2017 |
| Tondziel Consultancy Ltd | Professional & scientific | 2018 |
| Tono Products Limited | Professional & scientific | 1991 |
| Tony Burns Carpentry Limited | Construction | 2014 |
| Tony Express Services Ltd | Construction | 2017 |
| Tony Perry Property Services Ltd | Administrative & support | 2022 |
| Tony Sewell Motors Ltd | Wholesale & retail | 2026 |
| Tool Fuel Limited | Wholesale & retail | 2023 |
| Tooled UP Raccoons Ltd | Information & communication | 2020 |
| Toolrite Limited | Manufacturing | 2003 |
| Top Bots Limited | Administrative & support | 2020 |
| Top Dog Walking and Boarding Ltd | Other services | 2024 |
| Top Drylining Contractors Limited | Construction | 2020 |
| Top Grape Enterprises Limited | Administrative & support | 2006 |
| Top Lettings Limited | Real estate | 2022 |
| Top Spec Painting Services Ltd | Construction | 2016 |
| Top Steelfixing Ltd | Construction | 2022 |
| Top Tidy Home Ltd | Wholesale & retail | 2024 |
| Top-Ad IT Solutions Limited | Information & communication | 2014 |
| Topron Consulting Limited | Information & communication | 2021 |
| Tops Events Ltd | Wholesale & retail | 2018 |
| Topsails Maintenance Limited | Administrative & support | 2021 |
| Toptier Driving School Ltd | Transport & logistics | 2024 |
| TOR Bryan (Residence) Limited | Households | 1965 |
| Toru E-Commerce Ltd | Wholesale & retail | 2025 |
| Toshiko Limited | Health & social care | 2014 |
| Toshipad Ltd | Real estate | 2022 |
| Total Builders Ltd | Construction | 2019 |
| Total Concrete Direct Ltd | Manufacturing | 2021 |
| Total Landscapes & Groundworks Limited | Administrative & support | 2013 |
| Total Mental Game Ltd | Arts & recreation | 2026 |
| Total Thermal Limited | Construction | 2017 |
| Totalfix.It Limited | Construction | 2014 |
| Totus Financial Services Limited | Professional & scientific | 2015 |
| Toucan Tango Music Limited | Arts & recreation | 1988 |
| Tower of Light Motion Picture Company Ltd | Information & communication | 2010 |
| Town & Country Fumigation Services Ltd | Administrative & support | 2026 |
| Town & Country Marble Ltd | Construction | 2003 |
| Town & Country Pests Ltd | Administrative & support | 2025 |
| Town & Countryside Land Acquisition & Development UK Ltd | Real estate | 2002 |
| Towner & SON Electrical Ltd | Professional & scientific | 2023 |
| Towrite Limited | Wholesale & retail | 2016 |
| TP1 Consultancy Ltd | Information & communication | 2016 |
| TPS Installations Ltd | Construction | 2010 |
| Tpsc Ltd | Wholesale & retail | 2018 |
| TPW Building Maintenance Ltd | Construction | 2024 |
| Trackdays Limited | Extraterritorial | 2009 |
| Tracy ANN Brimelow Limited | Administrative & support | 2017 |
| Tracy Hunt Equestrian Ltd | Agriculture & fishing | 2013 |
| Trade Conservatories 2 U Limited | Construction | 2005 |
| Trade Direct Sales Ltd | Wholesale & retail | 2016 |
| Trade Flow Marketing Ltd | Professional & scientific | 2025 |
| Trade Motor Salvage Ltd | Wholesale & retail | 2025 |
| Trade Price Cars Limited | Wholesale & retail | 2015 |
| Trade Vehicle Locks (UK) Limited | Extraterritorial | 2013 |
| Trade Vehicle Locks Limited | Administrative & support | 2020 |
| Tradelink Global Ventures Limited | Wholesale & retail | 2025 |
| Tradewinds Offshore Environmental Limited | Professional & scientific | 2011 |
| Tradex Insurance Company PLC | Financial services | 1994 |
| Trading Plastics Ltd | Wholesale & retail | 2023 |
| Trafalgar Coins Limited | Wholesale & retail | 2021 |
| Trailhead Holdings Ltd | Information & communication | 2025 |
| Trailnet C.I.C | Arts & recreation | 2008 |
| Traki Solutions Ltd | Professional & scientific | 2025 |
| Tramore & Essex Property Management Ltd | Real estate | 2022 |
| Tranquility Print Ltd | Manufacturing | 2016 |
| Trans-Urban Limited | Administrative & support | 1997 |
| Trans-X ALS Ltd | Wholesale & retail | 2021 |
| Transactify Ltd | Construction | 2024 |
| Transform Your Property Ltd | Construction | 2021 |
| Transformer Managers International Ltd | Construction | 2026 |
| Transocean Property Ltd | Real estate | 2022 |
| Transpire Training Limited | Professional & scientific | 2018 |
| Trash UK (the Show) Limited | Administrative & support | 2024 |
| Travelling With Taste Ltd | Administrative & support | 2018 |
| TRD Construction Ltd | Construction | 2026 |
| Treasure Island Holdings Limited | Hospitality | 2018 |
| Treble-Twenty Cars and Couriers Limited | Transport & logistics | 1992 |
| Tree Hub Farms Ltd | Information & communication | 2024 |
| Tremain Holdings Limited | Financial services | 2024 |
| Trend Development Limited | Real estate | 2006 |
| Trend Properties Limited | Construction | 1994 |
| Triangle Consultants Ltd | Professional & scientific | 2023 |
| Triangulan Limited | Professional & scientific | 2009 |
| Trident Cleaning Services | | 1996 |
| Trident Data & Voice Ltd | Construction | 2022 |
| Triggs Garage Ltd | Wholesale & retail | 2014 |
| Trillestates Ltd | Construction | 2020 |
| Tring Care Limited | Health & social care | 2020 |
| Trinity College Dublin Association Cambridge Branch | Education | 2011 |
| Trinity Real Estate Ventures Ltd | Real estate | 2025 |
| Trio Tools Limited | Manufacturing | 1966 |
| Trip Holdings Ltd | Real estate | 2020 |
| Trip Property 1 Ltd | Real estate | 2020 |
| Trip Property Ltd | Real estate | 2019 |
| Triple B Nutrition Ltd | Manufacturing | 2025 |
| Triple B Solutions Ltd | Professional & scientific | 2009 |
| Triple Oaks Joinery Ltd | Manufacturing | 2026 |
| Triple R Wheel Systems Limited | Wholesale & retail | 2023 |