| Tulip Luton Hotel Opco Ltd | Hospitality | 2022 |
| Tunisco Services Ltd | Administrative & support | 2025 |
| Tunnel Aluminium Systems Limited | Construction | 2020 |
| Tuohy Surveys Ltd | Construction | 2015 |
| Turkish Fine Wines Ltd | Wholesale & retail | 2014 |
| Turkuaz Bar and Grill Ltd | Hospitality | 2024 |
| Turkuaz Exhibition Agency Ltd | Professional & scientific | 2026 |
| Turner Tools Limited | Wholesale & retail | 2020 |
| Tuzy London Limited | Other services | 2026 |
| Tvdc Consultancy Limited | Administrative & support | 2023 |
| TWB Properties Ltd | Real estate | 2018 |
| Tweak (London) Limited | Health & social care | 2021 |
| Tweak North Limited | Health & social care | 2024 |
| Twelfth Gate Properties Ltd | Real estate | 2017 |
| Twelve Charles Street (Tenants) Limited | Households | 1976 |
| Twenty One Homes Ltd | Real estate | 2018 |
| TWENTY20 Estates Ltd | Real estate | 2020 |
| Twentyseven Tech Ltd | Information & communication | 2017 |
| Twin Insights Ltd | Information & communication | 2026 |
| Twinkles Domestic Cleaning Services Limited | Construction | 2014 |
| Two of a Kind Futures Limited | Financial services | 2013 |
| Two Smoking Barrels Limited | Administrative & support | 2006 |
| TYF Services Ltd | Professional & scientific | 2025 |
| Tyrone Group Limited | Wholesale & retail | 2003 |
| Tyrone Textiles Limited | Wholesale & retail | 1978 |
| Tyronette Manufacturing Limited | Professional & scientific | 1990 |
| Tyty TRANS2017 Ltd | Transport & logistics | 2024 |
| U Apparel Limited | Wholesale & retail | 2015 |
| U R Blend Ltd | Hospitality | 2017 |
| U-Plum Ltd | Construction | 2017 |
| U-Turn Interiors Limited | Wholesale & retail | 2008 |
| UB Foods Ltd | Wholesale & retail | 2021 |
| UBS Building Services Engineers Limited | Construction | 2009 |
| UBS Building Services Maintenance Ltd | Construction | 2014 |
| UCA Fitness Ltd | Arts & recreation | 2023 |
| UD Music Foundation | Arts & recreation | 2012 |
| UD Music Ltd | Information & communication | 2012 |
| Uddinson Ltd | Real estate | 2025 |
| Uganda Cranes UK CIC | Arts & recreation | 2025 |
| Uglows (Chingford) Limited | Wholesale & retail | 1948 |
| UK Car Wash Limited | Wholesale & retail | 2026 |
| UK Certification & Compliance Ltd | Professional & scientific | 2025 |
| UK Food Exchange Ltd | Wholesale & retail | 2017 |
| UK Great Consultants Ltd | Professional & scientific | 2020 |
| UK Great Way Ltd | Information & communication | 2020 |
| UK Locksmiths Association Limited | Education | 2005 |
| UK Packaging Online Ltd | Administrative & support | 2022 |
| UK Property Ventures Limited | Real estate | 2013 |
| UK Road Pro Limited | Education | 2025 |
| UK Smart Support Ltd | Professional & scientific | 2023 |
| UK Trade Limited | Real estate | 2005 |
| UK Trade Supplies Limited | Construction | 1999 |
| Ukey Car Solution Ltd | Wholesale & retail | 2023 |
| Ultimate Blue Limited | Health & social care | 2021 |
| Ultimate Data Solutions Ltd | Information & communication | 2009 |
| Ultimate Gym 1 Limited | Arts & recreation | 2022 |
| Ultimate Support Services Group (Ussg) Ltd | Professional & scientific | 2019 |
| Ultra Kids Ltd | Real estate | 2006 |
| Ultrapulse Limited | Construction | 2007 |
| UME Salon Ltd | Other services | 2023 |
| Umiya Group Ltd | Wholesale & retail | 2026 |
| UMM AL Qura Foundation | Health & social care | 2018 |
| Unavelle Limited | Construction | 2026 |
| Underdog Music Management Ltd | Information & communication | 2024 |
| Underdogs on Top Publishing Ltd | Information & communication | 2024 |
| Undone Lingerie Limited | Administrative & support | 2012 |
| Uneek Global Limited | Administrative & support | 2022 |
| Unicall Limited | Manufacturing | 1994 |
| Unified Payroll Solutions Ltd | Administrative & support | 2026 |
| Uniksb Solutions Limited | Administrative & support | 2015 |
| Unique Fashion Maker Limited | Professional & scientific | 2018 |
| Unique Quickbuys Ltd | Wholesale & retail | 2023 |
| Unisoft Limited | Professional & scientific | 2012 |
| Universal Bargain Ltd | Wholesale & retail | 2013 |
| Universal Plastering Ltd | Construction | 2007 |
| Unlimited Futures Ltd | Administrative & support | 2014 |
| UNO Hire Services Limited | Administrative & support | 2016 |
| Unobra Ltd | Administrative & support | 2023 |
| UP Space 24 Limited | Financial services | 2024 |
| UP Space Events Limited | Hospitality | 2019 |
| UP Space Holdings Limited | Financial services | 2016 |
| UP Space Limited | Hospitality | 2015 |
| Uphaar Limited | Wholesale & retail | 2004 |
| Uphall Alexandra Ltd | Real estate | 2022 |
| Uphall Evesrill Limited | Construction | 2025 |
| Uphall Investments Limited | Construction | 1964 |
| Upminster Fencing Limited | Manufacturing | 2002 |
| Upminster Property Ltd | Real estate | 2018 |
| Upon Angels' Wings Ltd | Administrative & support | 2021 |
| Uptown Jamaican Takeway Ltd | Hospitality | 2025 |
| Uptown Legal Limited | Professional & scientific | 2026 |
| Urban Creative Limited | Real estate | 2008 |
| Urban Development | Education | 2000 |
| Urban Earth Gardens Ltd | Administrative & support | 2011 |
| Urban Nestfinders Ltd | Real estate | 2022 |
| Urban Rise Investment Ltd | Real estate | 2024 |
| Urban Westwood Limited | Financial services | 2019 |
| Us:Kin Aesthetic Clinic Ltd | Health & social care | 2023 |
| Ushadow Ltd | Information & communication | 2025 |
| Ustun Meat Ltd | Manufacturing | 2019 |