| Tower Transit Asset Holdings Limited | Transport & logistics | 2017 |
| Tower Transit Limited | Transport & logistics | 2001 |
| Tower Transit Operations Ltd | Transport & logistics | 2012 |
| Towercomms Limited | Construction | 2004 |
| Town & Country Conservatories Limited | Construction | 2015 |
| Town Cars Northampton Limited | Transport & logistics | 2024 |
| Town Electrical Solutions Ltd | Construction | 2023 |
| Town Taxis Ltd | Transport & logistics | 2024 |
| Towns Tyres Northampton Limited | Wholesale & retail | 2026 |
| Townwide Property Services Limited | Construction | 2002 |
| Towpath Group Ltd | Administrative & support | 2018 |
| Toymaster Limited | Wholesale & retail | 1988 |
| Toyo Tyre (UK) Limited | Administrative & support | 2005 |
| Toytimate Ltd | Wholesale & retail | 2025 |
| TP Directors Ltd | Extraterritorial | 1997 |
| TP Property Company Limited | Construction | 2018 |
| TP Property Enterprises Limited | Real estate | 2018 |
| TPD Marketing Ltd | Professional & scientific | 2020 |
| TPG Management Services Limited | Extraterritorial | 2014 |
| TPL Truck and Trailer Ltd | Wholesale & retail | 2024 |
| TPN Ltd | Administrative & support | 1997 |
| TPP Collects Limited | Wholesale & retail | 2025 |
| TPP Consult and Serve Ltd | Information & communication | 2019 |
| TPP London Properties Ltd | Real estate | 2021 |
| Tpro Creative Media Ltd | Information & communication | 2023 |
| TR Bejat Ltd | Construction | 2025 |
| TR Lifting Services Limited | Professional & scientific | 2016 |
| TR Palecek Ltd | Real estate | 2026 |
| TR Probuild Ltd | Construction | 2026 |
| TR Transport Northampton Ltd | Transport & logistics | 2024 |
| Tr&Ac Limited | Transport & logistics | 2018 |
| Tracey Messinger Coaching Limited | Education | 2026 |
| Track NN C.I.C. | Education | 2017 |
| Track One Consulting Ltd | Professional & scientific | 2025 |
| Track Safe Tech Solutions Ltd | Professional & scientific | 2026 |
| Trackline Ltd | Manufacturing | 2012 |
| Tracys Care @Home Limited | Hospitality | 2021 |
| Trade Carpet Centre Limited | Wholesale & retail | 2014 |
| Trade Door Properties Limited | Real estate | 1990 |
| Trade Parts Direct Limited | Wholesale & retail | 2021 |
| Trade Pipes Limited | Wholesale & retail | 2018 |
| Trade Smart Limited | Transport & logistics | 2005 |
| Trade Start UK Ltd | Administrative & support | 2026 |
| Trade X Hub Ltd | Wholesale & retail | 2022 |
| Tradecars Direct Ltd | Wholesale & retail | 2003 |
| Tradeforce Air Conditioning Limited | Construction | 2015 |
| Tradel Ltd | Extraterritorial | 2023 |
| Tradella Ltd | Wholesale & retail | 2019 |
| Traders for Fair Trading Ltd | Information & communication | 2014 |
| Tradesman Competitions Limited | Professional & scientific | 2024 |
| Tradesman Tools Shop Limited | Wholesale & retail | 2020 |
| Tradestar International Limited | Information & communication | 2004 |
| Tradevana Ltd | Information & communication | 2025 |
| Tradewinds Enterprise Ltd | Wholesale & retail | 2007 |
| Tradistics Ltd | Wholesale & retail | 2025 |
| Traektoria Ltd | Transport & logistics | 2022 |
| Trafiq Limited | Extraterritorial | 2014 |
| Tragus Limited | Professional & scientific | 2016 |
| Train to Learn Ltd | Professional & scientific | 2017 |
| Training Event Safety Solutions Ltd | Public administration | 2009 |
| Tranquility Lounge Mind & Body Ltd | Health & social care | 2025 |
| Tranquillitas Therapy Ltd | Health & social care | 2023 |
| Trans Benek Ltd | Transport & logistics | 2025 |
| Trans Lord UK Ltd | Wholesale & retail | 2016 |
| Trans Prem Ltd | Transport & logistics | 2023 |
| Trans STO Ltd | Transport & logistics | 2023 |
| Trans Vali Ltd | Transport & logistics | 2023 |
| Transcop Ltd | Transport & logistics | 2023 |
| Transformationfot Ltd | Wholesale & retail | 2025 |
| Transglobal Cargo Shipping Ltd | Transport & logistics | 2023 |
| Transilvania Transport Limited | Transport & logistics | 2018 |
| Transitpro Logistics Ltd | Transport & logistics | 2025 |
| Transloader Services Limited | Manufacturing | 2003 |
| Transminerals (UK) Limited | Mining & quarrying | 2016 |
| Transnova Logistics Ltd | Transport & logistics | 2025 |
| Transport Arnasj Ltd | Transport & logistics | 2016 |
| Transport G&I Ltd | Transport & logistics | 2024 |
| Transport Rely UK Ltd | Transport & logistics | 2020 |
| Transport SB Ltd | Transport & logistics | 2015 |
| Transport V Limited | Transport & logistics | 2023 |
| Transportdal Ltd | Wholesale & retail | 2025 |
| Transrok Limited | Transport & logistics | 2017 |
| Transspeed Ltd | Wholesale & retail | 2014 |
| Transvalue Property LLP | | 2025 |
| Transworld Payment Solutions U.K. Limited | Professional & scientific | 1979 |
| Transylvanya (Northampton) Ltd | Wholesale & retail | 2012 |
| Tranzaura Technologies Limited | Information & communication | 2005 |
| Tranzaura UK Limited | Administrative & support | 2012 |
| Tranzr Group Limited | Wholesale & retail | 2020 |
| Trapasso Properties Ltd | Real estate | 2019 |
| Trappd (Billing) Ltd | Arts & recreation | 2018 |
| Trappd GE1 Ltd | Arts & recreation | 2018 |
| Trappd Ltd | Arts & recreation | 2016 |
| Trappd Peterborough Ltd | Arts & recreation | 2017 |
| Trasler Limited | Financial services | 2013 |
| Trasrail Services Limited | Professional & scientific | 2016 |
| Travcom UK Ltd | Wholesale & retail | 2020 |
| Travel Coolpass Ltd. | Administrative & support | 2019 |
| Travel Ease Cars Ltd | Transport & logistics | 2024 |
| Travel Links Solution Ltd | Wholesale & retail | 2025 |