| TMC (Northants) Limited | Financial services | 2003 |
| TMT Property Renovations and Lettings Ltd | Real estate | 2024 |
| Tndl Logistics Limited | Transport & logistics | 2020 |
| Tobi Repairs Ltd | Wholesale & retail | 2017 |
| Tokssan Limited | Administrative & support | 2015 |
| Tola Foods Ltd | Wholesale & retail | 2025 |
| Tola-Voss Limited | Hospitality | 2019 |
| Tom-Tec Engineering Ltd | Professional & scientific | 2018 |
| Tomas Driver Ltd | Transport & logistics | 2013 |
| Tomasz Green Ltd | Wholesale & retail | 2025 |
| Tomatoes Group Limited | Professional & scientific | 2021 |
| Tomix Ltd | Wholesale & retail | 2025 |
| Tomlej Ltd | Manufacturing | 2016 |
| Tong Hing UK Ltd | Wholesale & retail | 2025 |
| Tony Dibbin Limited | Administrative & support | 2013 |
| Toop Transport Ltd | Transport & logistics | 2025 |
| Top Fadez Limited | Other services | 2022 |
| Top G Care Limited | Health & social care | 2023 |
| Top Lodge Leisure Limited | Professional & scientific | 2003 |
| Top Tier Learning Limited | Education | 2025 |
| TOR21 Limited | Administrative & support | 2020 |
| Torchwood UK Limited | Professional & scientific | 2007 |
| Torney Limited | Administrative & support | 1997 |
| Torrevie Limited | Real estate | 2025 |
| Total Commercial Ltd | Real estate | 2025 |
| Total Plant Limited | Administrative & support | 2001 |
| Total Tower Cranes Limited | Administrative & support | 2014 |
| Total Ventilation Solutions Limited | Professional & scientific | 2022 |
| Totalclean Mastery Ltd | Wholesale & retail | 2025 |
| Totol Ltd | Wholesale & retail | 2014 |
| Towa Ltd | Wholesale & retail | 2026 |
| TP Rockwealth Properties Ltd | Real estate | 2025 |
| TPC Ukco Limited | Professional & scientific | 2021 |
| TPF Capital Ltd | Real estate | 2026 |
| TR Scaffold Limited | Construction | 2020 |
| TR Scaffold Services and Hire Limited | Financial services | 2025 |
| Track BHR Limited | Other services | 2020 |
| Track Dynamics Ltd | Wholesale & retail | 2020 |
| Trade Lazer Ltd | Administrative & support | 2024 |
| Tradeforce International Limited | Wholesale & retail | 1999 |
| Traffco Limited | Wholesale & retail | 2004 |
| Traffy Flute Engineers Ltd | Construction | 2026 |
| Trail to Sail Adventures Ltd | Administrative & support | 2026 |
| Trainingpro Ltd | Education | 2022 |
| Trams Alavesa 1 Ltd | Transport & logistics | 2019 |
| Tranquillo Cyber Limited | Information & communication | 2026 |
| Trans MIB Ltd | Transport & logistics | 2024 |
| Trans SIM Ltd | Transport & logistics | 2024 |
| Trans&Go Ltd | Construction | 2024 |
| Translita Ltd | Transport & logistics | 2015 |
| Transport Hardy Ltd | Transport & logistics | 2024 |
| Transporter Holdings Limited | Financial services | 2019 |
| Transporter Solutions Limited | Wholesale & retail | 2012 |
| Traybe Ltd | Professional & scientific | 2026 |
| Treasure Chocolates Limited | Manufacturing | 2001 |
| Treble F Limited | Health & social care | 2022 |
| Trelectrom Limited | Construction | 2025 |
| Tremblemax Ltd | Real estate | 2014 |
| Trenchant Systems Ltd | Information & communication | 2007 |
| Trent END Holdings Limited | Professional & scientific | 2011 |
| Trent Property Ltd | Real estate | 2016 |
| Tri-Point Talent Management Ltd | Information & communication | 2025 |
| Tribal Consulting Ltd | Professional & scientific | 2023 |
| Trifanline Ltd | Transport & logistics | 2019 |
| Triline Ltd | Water & waste | 2026 |
| Trinity Accountancy Ltd | Professional & scientific | 2026 |
| Trintus Care Ltd | Health & social care | 2022 |
| Triplar Limited | Manufacturing | 1983 |
| Triple a Specialist Cleaning Services Ltd | Administrative & support | 2023 |
| Tripple J Care Services Ltd | Health & social care | 2022 |
| Trradek Ltd | Transport & logistics | 2021 |
| True Nigerian Worldwide Organisation | Other services | 2013 |
| Trueedge Talent Ltd | Administrative & support | 2025 |
| Truestar Talent Limited | Administrative & support | 2015 |
| Trusted Steps Ltd | Health & social care | 2024 |
| TSA Motors Ltd | Manufacturing | 2017 |
| TSR in Corby Ltd | Hospitality | 2019 |
| TSS Construct Ltd | Construction | 2021 |
| TTM Smart Ltd | Wholesale & retail | 2025 |
| Tudor Smart Repair Ltd | Wholesale & retail | 2018 |
| Tudor Street Opco Limited | Real estate | 2017 |
| Tumbale Consultancy Limited | Administrative & support | 2024 |
| Tupcy Healthcare Limited | Health & social care | 2014 |
| Turbinka Express Limited | Transport & logistics | 2025 |
| Turmacher Ltd | Manufacturing | 2018 |
| Turner Parris Properties Ltd | Real estate | 2025 |
| Turnright Consultancy Limited | Administrative & support | 2018 |
| Turpe Ltd | Professional & scientific | 2022 |
| Tutuscuisine Ltd | Hospitality | 2026 |
| Tvtm Ltd | Public administration | 2019 |
| Twin Finance One Limited | Financial services | 2016 |
| TWM Digital Limited | Information & communication | 2016 |
| Twor Services Ltd | Professional & scientific | 2026 |
| Twyco Global Ltd | Manufacturing | 2023 |
| Twywell Land LLP | | 2008 |
| Tyby Trans Ltd | Transport & logistics | 2022 |
| Tygen Investiments Limited | Health & social care | 2011 |
| Tymkad Driver Ltd | Administrative & support | 2018 |
| Tynutrans Ltd | Transport & logistics | 2022 |
| Typhoon Solutions Ltd | Information & communication | 2024 |