| Trutalent Ltd | Professional & scientific | 2020 |
| Truth Homes SPV Limited | Real estate | 2019 |
| TS Electrical (UK) Limited | Construction | 2009 |
| TS Site Services Limited | Construction | 2006 |
| TSD Property Services Ltd | Real estate | 2025 |
| TSD Safety Services Ltd | Construction | 2018 |
| TSL Scaffolding Services Ltd | Construction | 2014 |
| TST Facilities Limited | Households | 2019 |
| TTM Rail Ltd | Other services | 2012 |
| Ttmb Limited | Health & social care | 2016 |
| Tudor Plastering Ltd | Construction | 2026 |
| Tunbridge Wells Barber Shop Limited | Other services | 2024 |
| Tunde OJO Touch Ltd | Other services | 2019 |
| Tungsten Global Limited | Professional & scientific | 2008 |
| Tunway Limited | Hospitality | 1973 |
| Turn and Burn Welding and Engineering Ltd | Extraterritorial | 2025 |
| Turnham Enterprises Ltd | Real estate | 2024 |
| Turning Point Mortgages Limited | Financial services | 2024 |
| Turning Tides Ltd | Agriculture & fishing | 2022 |
| Turnkey Contracting Ltd | Construction | 2017 |
| Turno Shop Limited | Wholesale & retail | 2025 |
| TUS Contractor Limited | Information & communication | 2014 |
| Tuto Ltd | Hospitality | 2020 |
| Tutoristic Limited | Extraterritorial | 2025 |
| TVL Limited | Administrative & support | 2013 |
| TW Mechanical Services Ltd | Construction | 2018 |
| TWENTY4SEVEN Property Maintenance Ltd | Administrative & support | 2016 |
| Twinkle and Sparkles Cleaning Services Limited | Administrative & support | 2024 |
| Twins Gravesend Ltd | Hospitality | 2019 |
| Two Doves Limited | Hospitality | 2025 |
| Twyst Ltd | Other services | 2022 |
| Tyche Growth Ltd | Real estate | 2023 |
| Tyche Management Solutions Limited | Information & communication | 2017 |
| Typodeal Properties Limited | Households | 1987 |
| Tzedakah Ltd | Health & social care | 2024 |
| U Cargo LLP | | 2011 |
| U I Jasnelven UK Ltd | Extraterritorial | 2020 |
| U K Property Investments Limited | Real estate | 2003 |
| U&L Ltd | Real estate | 2019 |
| U. B. Drylining Ltd | Construction | 2013 |
| UA Protection Group Limited | Administrative & support | 2026 |
| UBL Site Services Ltd | Real estate | 2024 |
| Uchechukwu EZE Ltd | Professional & scientific | 2022 |
| UD Excel Ventures (UK) Limited | Professional & scientific | 2020 |
| Uday Limited | Construction | 2016 |
| UFC Constructions Limited | Construction | 2026 |
| UFC Gym Nottingham Limited | Arts & recreation | 2023 |
| Uforia EST 22 Ltd | Wholesale & retail | 2022 |
| UK 2 ZIM Shipping Company Limited | Transport & logistics | 2025 |
| UK Buildings Contractor Ltd | Construction | 2017 |
| UK Construction WM Ltd | Manufacturing | 2025 |
| UK Cosy Stays Ltd | Real estate | 2024 |
| UK Divine Care Ltd | Real estate | 2021 |
| UK Elite-Events Limited | Other services | 2016 |
| UK Financial Consultancy Services Limited | Administrative & support | 2005 |
| UK Flooring Centre Ltd | Wholesale & retail | 2018 |
| UK Gold Scissorss Ltd | Other services | 2022 |
| UK Healthcare Network Limited | Administrative & support | 2013 |
| UK List and Press Services Limited | Information & communication | 2005 |
| UK London Apartments Ltd | Hospitality | 2026 |
| UK Network Connections Ltd | Construction | 2019 |
| UK Simply Furniture Ltd | Wholesale & retail | 2025 |
| UK Staff Payroll Ltd | Administrative & support | 2025 |
| UK Switching and Isolations Ltd | Energy | 2024 |
| UK Total Building Solutions Ltd | Construction | 2018 |
| UK Wine & Food Supplies Ltd | Wholesale & retail | 2012 |
| UK Wineries Limited | Manufacturing | 2017 |
| Ukinect Limited | Information & communication | 2012 |
| Ukpa Supply Services Ltd | Professional & scientific | 2010 |
| Ukshopgb Ltd | Wholesale & retail | 2022 |
| ULD Ltd | Real estate | 2019 |
| Ultimate Care Provider Ltd | Health & social care | 2019 |
| Ultimate Flooring Solutions Ltd | Households | 2010 |
| Ultimate Tapers Ltd | Construction | 2017 |
| Ultimate Training Investments Limited | Administrative & support | 2024 |
| Ultraclean Carbon Credits Limited | Professional & scientific | 2024 |
| Ultraclean Global Limited | Professional & scientific | 2023 |
| Ultracut Limited | Professional & scientific | 2018 |
| Ulysses Facilities Management Limited | Wholesale & retail | 2020 |
| UM Marketing Ltd | Wholesale & retail | 2024 |
| Umair Holdings Ltd | Financial services | 2026 |
| UMI Traders Ltd | Wholesale & retail | 2024 |
| Uneqe Construction Ltd | Construction | 2016 |
| Unic Services (UK) Limited | Administrative & support | 2011 |
| Unicom Welding Services Ltd | Construction | 2013 |
| Unicorn Maintenance Services Limited | Professional & scientific | 1994 |
| Unicursal Limited | Information & communication | 2009 |
| Unify Security Group Limited | Administrative & support | 2024 |
| Unik Drylining Ltd | Construction | 2018 |
| Union Business Finance Limited | Extraterritorial | 2010 |
| Union House Residents Company Limited | Households | 2006 |
| Unions Cash and Carry Limited | Other services | 2019 |
| Uniproperties Ltd | Households | 2023 |
| Unique Contracts Limited | Construction | 2017 |
| Unique Foods (London) Ltd | Hospitality | 2026 |
| Unique-Gap Care Services Ltd | Health & social care | 2023 |
| Unisites Ltd | Information & communication | 2024 |
| Unit 6 AV Event Solutions Ltd | Arts & recreation | 2025 |
| United Jointers Ltd | Construction | 2013 |
| Uniteq Limited | Information & communication | 2018 |