| Trafalgar Property Holdings Limited | Real estate | 2021 |
| TRAIN2FIGHT UK Limited | Arts & recreation | 2016 |
| Transformational Consulting Limited | Professional & scientific | 2014 |
| Transport 24 International Forwarding Ltd | Wholesale & retail | 2021 |
| Tread Networks Ltd | Information & communication | 2010 |
| Trend & Thomas Commercial Limited | Real estate | 2010 |
| Tria Nomina Limited | Administrative & support | 2007 |
| Trinity Education Group Limited | Education | 2023 |
| Triple Seven (UK) Limited | Wholesale & retail | 2008 |
| Tristar Consultancy Limited | Professional & scientific | 2024 |
| Trivedi Design LAB Ltd | Administrative & support | 2015 |
| TRK Technology Ltd | Information & communication | 2014 |
| TRM Holdco Limited | Financial services | 2026 |
| Tropiland Limited | Wholesale & retail | 2024 |
| Trout Rise Chesham Ltd | Construction | 2017 |
| Trout Rise Chorleywood Ltd | Real estate | 2017 |
| Trout Rise Developments Ltd | Construction | 2014 |
| Trout Rise Management Limited | Real estate | 2014 |
| Trout Rise Ruislip Ltd | Real estate | 2017 |
| Troy Property Management Limited | Real estate | 2019 |
| True Grain Carpentry Ltd | Manufacturing | 2025 |
| Trueflight Simulation Limited | Arts & recreation | 2020 |
| Trunk Lifestyle Boutique Ltd | Wholesale & retail | 2022 |
| Trurock Limited | Professional & scientific | 2025 |
| Trustworthy Childcare Ltd | Health & social care | 2025 |
| Trybeca Investments Limited | Information & communication | 2004 |
| Trytec 223 LLP | | 2025 |
| TS IT Consultancy Limited | Information & communication | 2017 |
| Tsfa Limited | Wholesale & retail | 2026 |
| TTB Construction Limited | Construction | 2015 |
| Tuci Coaching & Consulting Ltd | Administrative & support | 2025 |
| Tuitionworks Limited | Education | 2021 |
| Tuning Group Europe Limited | Information & communication | 2002 |
| Turfcare Maintenance Limited | Other services | 2001 |
| Turnham Green Newsagent Limited | Wholesale & retail | 2014 |
| Turnpike END Management Limited | Households | 1996 |
| Turnround Directors Limited | Professional & scientific | 2006 |
| Turret Group Limited | Information & communication | 1988 |
| Turret Media Limited | Information & communication | 2004 |
| TUS NUA Estates Limited | Construction | 2024 |
| Twenty-Six Hatherley Grove Limited | Real estate | 1989 |
| TWENTY14 Consulting Ltd | Information & communication | 2016 |
| TWH Chorleywood Limited | Hospitality | 2017 |
| Two and a Half Bears Limited | Information & communication | 2016 |
| U.B. Autos Ltd | Wholesale & retail | 2012 |
| Uddanda Limited | Information & communication | 2010 |
| Ukftb.Com Limited | Administrative & support | 2004 |
| Ultima Money Limited | Administrative & support | 2008 |
| UN Properties Limited | Real estate | 2021 |
| Una's World Holding Limited | Information & communication | 2026 |
| Unavu Ltd | Hospitality | 2023 |
| Uncertainty Quantification Limited | Professional & scientific | 2017 |
| Undercover Garage Limited | Wholesale & retail | 2025 |
| Unequalled Media Limited | Information & communication | 2015 |
| UNI Support Centre Ltd | Education | 2020 |
| Unicorn Global Limited | Wholesale & retail | 2015 |
| Unified Telecoms Supplier Limited | Wholesale & retail | 2024 |
| Unifruit Group Limited | Financial services | 2011 |
| Unifruit Limited | Wholesale & retail | 1984 |
| Unique Genre Enterprise Limited | Wholesale & retail | 2016 |
| Unisons Group Ltd | Other services | 2024 |
| Unite Conferencing Limited | Information & communication | 2002 |
| Unite Locums Limited | Health & social care | 2012 |
| United Property Investments Limited | Real estate | 2004 |
| Universal Businesses Limited | Professional & scientific | 2008 |
| Universal Civil Engineering Solutions Limited | Construction | 2007 |
| Universal Trading Services Limited | Wholesale & retail | 2007 |
| Unomundi Limited | Information & communication | 2026 |
| Untethered PR Limited | Professional & scientific | 2023 |
| Untold Films Limited | Information & communication | 2012 |
| Upgrade Interiors Ltd | Construction | 2019 |
| Upper GI Medical Services Limited | Health & social care | 2021 |
| V & a & R Ganatra Limited | Real estate | 2014 |
| V & P (2030) Ltd | Wholesale & retail | 2024 |
| V 2 V Community Church International Limited | Other services | 2017 |
| VA Healthcare Services Group Ltd | Health & social care | 2025 |
| Valley Farm Limited | Agriculture & fishing | 2003 |
| Valora Inc Ltd | Wholesale & retail | 2024 |
| Vansh Properties Limited | Real estate | 2017 |
| Vasefull Limited | Professional & scientific | 1998 |
| Vault Homes Limited | Construction | 2009 |
| Vchris Limited | Information & communication | 2004 |
| Vectorshift Ltd | Administrative & support | 2024 |
| Vedra Fitness Ltd | Arts & recreation | 2025 |
| Veelink Ltd | Administrative & support | 2015 |
| Veincare London Limited | Health & social care | 2014 |
| Vendo Nexus Ltd | Professional & scientific | 2019 |
| Vento Grecale Ltd | Construction | 2019 |
| Venture Design & Build Limited | Construction | 2017 |
| Verismart (Watford) Limited | Administrative & support | 2019 |
| Vers Finance Consulting Ltd | Professional & scientific | 2022 |
| Vertebra Ltd | Real estate | 2022 |
| Vertex Global Workplace Solutions Ltd | Construction | 2025 |
| Vertex Investing Limited | Education | 2019 |
| Veterinary Neurology Limited | Professional & scientific | 2003 |
| Vguard Life Limited | Financial services | 2018 |
| VH Dent and Partners Ltd | Health & social care | 2011 |
| Vicarage Green Properties Ltd | Real estate | 2013 |
| Victor Bravo Flying Ltd | Arts & recreation | 2014 |
| Victoria Frost Equestrian Ltd | Arts & recreation | 2021 |