| Therm Conservation Limited | Construction | 1977 |
| Thermal Plumbing Ltd | Construction | 2011 |
| THF Property Limited | Agriculture & fishing | 2017 |
| Thibaut Inc. | | 2007 |
| Thinking for Business Ltd | Professional & scientific | 2012 |
| Third Way Ventures Ltd | Real estate | 2024 |
| Thirteen Ways Limited | Professional & scientific | 2015 |
| Thistle Rose Property Services Limited | Construction | 2023 |
| Thistle Training and Consultancy Limited | Administrative & support | 2022 |
| Thomson Treasure Ltd | Wholesale & retail | 2024 |
| Thoresby Park Polo Club C.I.C. | Health & social care | 2021 |
| Thornhouse Holdings Limited | Professional & scientific | 2026 |
| Thornlea Developments (Oldham) Limited | Real estate | 1970 |
| Three Bears Productions Ltd | Arts & recreation | 2016 |
| Three CBD Ltd | Wholesale & retail | 2025 |
| Three Shires Caravan Storage Limited | Real estate | 2007 |
| Three SIX Nine Group Ltd | Administrative & support | 2020 |
| Three Supplements Limited | Wholesale & retail | 2025 |
| Thrsty Labs Ltd | Professional & scientific | 2025 |
| Thulshan Software Solutions Ltd | Information & communication | 2020 |
| Tiddlers Day Nursery and Preschool Limited | Education | 2025 |
| Tideline Services Limited | Information & communication | 2017 |
| Tigzz Limited | Manufacturing | 2021 |
| TIM Harries and Partners LLP | | 2010 |
| TIM Parkinson Limited | Information & communication | 2017 |
| Timetable Productions Limited | Information & communication | 2019 |
| Timico Partner Services Limited | Extraterritorial | 1995 |
| Timico Placeholder Limited | Professional & scientific | 2020 |
| Timico Technology Services Limited | Extraterritorial | 1998 |
| Tinderbox Sport Horses Limited | Other services | 2012 |
| Tinned Fish Reviews Ltd | Wholesale & retail | 2025 |
| Tinsley Tile Fixers Ltd | Administrative & support | 2016 |
| Tinto and Tea Ltd | Education | 2025 |
| Titan Business Growth Ltd | Professional & scientific | 2018 |
| TJ Cricket UK Limited | Manufacturing | 2025 |
| Tj's Retail Consultants Limited | Professional & scientific | 2014 |
| TJR Brickwork Specialist Limited | Construction | 2025 |
| TMH Ltd | Wholesale & retail | 2021 |
| TNC Enterprises Limited | Manufacturing | 2025 |
| TNT Nails Ltd | Other services | 2021 |
| Tocholach Properties Limited | Real estate | 2025 |
| Todd Property Holdings Limited | Real estate | 2025 |
| Together Works Bookkeeping Ltd | Professional & scientific | 2025 |
| Tojake Business Advisory Ltd | Professional & scientific | 2019 |
| Tolola Simbo Limited | Wholesale & retail | 2019 |
| Tolola Simbo SPV Ltd | Real estate | 2025 |
| TOM Bell Properties Ltd | Real estate | 2025 |
| TOM Cowling Ltd | Construction | 2019 |
| TOM Geraghty & Associates Limited | Professional & scientific | 2015 |
| TOM T Homes Limited | Construction | 2023 |
| Tomras Road Markings Ltd | Construction | 2023 |
| Tomvil Services Ltd | Construction | 2026 |
| Tony Muxlow Developments Ltd | Education | 2017 |
| Tooley Motorsport Ltd | Arts & recreation | 2021 |
| Top CUT Gents Barber 1 Ltd | Other services | 2026 |
| Top Deals 4 Wheels Ltd | Transport & logistics | 2024 |
| Total Care Security Limited | Administrative & support | 2007 |
| Total Device Solutions Limited | Wholesale & retail | 2020 |
| Total Water Systems Ltd | Wholesale & retail | 2018 |
| Tots and Tales U.K. Limited | Health & social care | 2025 |
| Touch One Solutions Limited | Information & communication | 2011 |
| Town & Country Grounds Limited | Administrative & support | 2017 |
| TOYOSUPRA01 Limited | Financial services | 2023 |
| TPM Compliance Training Solutions Ltd | Education | 2017 |
| TPM Digital Ltd | Information & communication | 2018 |
| TPM Trustee Services Limited | Extraterritorial | 2018 |
| TPM Trustees Limited | Extraterritorial | 2018 |
| TQ Services Ltd | Construction | 2022 |
| TR Enterprises (Trent) Ltd | Administrative & support | 2014 |
| Trade Airfreight Limited | Transport & logistics | 2026 |
| Trade Frames Newark Ltd | Professional & scientific | 2004 |
| Trade Freight International Limited | Transport & logistics | 2008 |
| Trade Gates Direct Ltd | Manufacturing | 2025 |
| Trade to Trade (UK) Limited | Information & communication | 2002 |
| Tradesmart Driveways and Landscaping Ltd | Administrative & support | 2025 |
| Training for Reality Ltd | Education | 2024 |
| Trajon Consultancy Limited | Information & communication | 2008 |
| Tramps (U.K.) Limited | Wholesale & retail | 1995 |
| Tranquility Beauty Newark Limited | Other services | 2024 |
| Transform Investments Limited | Real estate | 2025 |
| Transform Middlebeck Ltd | Arts & recreation | 2023 |
| Transformation NOW Limited | Professional & scientific | 2017 |
| Transport SS1012 Ltd | Transport & logistics | 2016 |
| Trendee Hair Ltd | Other services | 2015 |
| Trendtroop Ltd | Wholesale & retail | 2025 |
| Trent Bank House Consultants Ltd | Professional & scientific | 2013 |
| Trent Ceramics Limited | Construction | 1978 |
| Trent Electrical Ltd | Construction | 2023 |
| Trent Facilities Management Ltd | Administrative & support | 2026 |
| Trent Tractors & Mowers Ltd | Administrative & support | 2015 |
| Trentside Ventures Limited | Agriculture & fishing | 2025 |
| Trevor Waude & Company Limited | Professional & scientific | 2005 |
| Tri-Ag (Notts) Limited | Administrative & support | 1988 |
| Tribe Digital Futures Ltd | Information & communication | 2025 |
| Trickle NET Equine Innovations Limited | Manufacturing | 2016 |
| Tridyn Consulting LLP | | 2023 |
| Trimcliff Limited | Extraterritorial | 1979 |
| Trinco Solutions Limited | Real estate | 2020 |
| Trinity Property & Developments Limited | Real estate | 2023 |
| Triple Seven Holdings Limited | Professional & scientific | 2015 |