| Triple T Theatre Arts Ltd | Arts & recreation | 2023 |
| Triplex Industrial Contractors Limited | Construction | 1978 |
| Triumph Twin Spares Ltd | Wholesale & retail | 2006 |
| Trivel Ltd | Real estate | 2021 |
| TRN Demolition Services Limited | Construction | 2024 |
| Troika Film Collective Ltd | Information & communication | 2023 |
| Trojan Consultancy Limited | Administrative & support | 2011 |
| Trojan Mechanical Solutions Ltd | Construction | 2025 |
| Trojanprotectivesolutions Ltd | Administrative & support | 2025 |
| TRR Engineering Ltd | Professional & scientific | 2024 |
| TRT - the Right Track CIC | Education | 2026 |
| Truck & Coach Services Limited | Construction | 1974 |
| Truestone Landscapes Limited | Administrative & support | 2024 |
| Trueview Assets Limited | Real estate | 2024 |
| Trueview Financial Services Limited | Financial services | 2023 |
| Trueview Holdings Limited | Financial services | 2025 |
| Truleigh Scrumptious Ltd | Hospitality | 2018 |
| Trunks Pressure Washing Ltd | Administrative & support | 2023 |
| Trust in Destino Ltd | Administrative & support | 2024 |
| Trust Padel Limited | Information & communication | 2023 |
| Trust Tyres Ltd | Manufacturing | 2024 |
| Trusted Commercial Cleaning Ltd | Administrative & support | 2025 |
| Trustmark Plans Limited | Professional & scientific | 2013 |
| Trydown Limited | Information & communication | 2007 |
| Tskr Properties Ltd | Real estate | 2023 |
| TSS (Trade Security Supplies) Limited | Administrative & support | 2018 |
| TSSHELF2 Ltd | Health & social care | 2012 |
| TSW Engineering Solutions Limited | Professional & scientific | 2022 |
| TT Bowling Limited | Manufacturing | 2013 |
| TT Business Consulting Ltd | Professional & scientific | 2004 |
| TT Theatre Arts LLP | | 2023 |
| TU Electrical Services Ltd | Construction | 2025 |
| Tugwell Consultancy Ltd | Financial services | 2024 |
| Tuitt Solutions Ltd | Administrative & support | 2025 |
| Tulip Partners Ltd | Professional & scientific | 2017 |
| Tuono Limited | Construction | 2019 |
| Turner & COX Limited | Wholesale & retail | 2014 |
| Turner Packaging Limited | Manufacturing | 1975 |
| Turner Pope Holdings Ltd | Financial services | 2024 |
| Turner Pope Investments (TPI) Ltd | Financial services | 2015 |
| Turtle Tots North London Ltd | Arts & recreation | 2020 |
| Turvec Holdings Limited | Financial services | 2022 |
| TVC Lighting Ltd | Information & communication | 2016 |
| Tverskoy Investments | Financial services | 2018 |
| TVL Group Limited | Financial services | 2020 |
| TVL Security Limited | Administrative & support | 2012 |
| TW Building Services Ltd | Construction | 2021 |
| Twelve Volts Limited | Administrative & support | 2008 |
| Twenty Twenty Capital Ltd | Professional & scientific | 2015 |
| Twenty Twenty Glengall Limited | Professional & scientific | 2016 |
| Twenty Twenty Holdings Limited | Professional & scientific | 2016 |
| Twenty Twenty Ilderton Limited | Professional & scientific | 2016 |
| Twenty Twenty Ilderton Wharf Limited | Real estate | 2019 |
| Twenty Twenty Norwood Limited | Real estate | 2019 |
| Twenty Twenty Penarth Limited | Real estate | 2018 |
| Twenty Twenty Stratford Limited | Professional & scientific | 2020 |
| Twenty Twenty Workspace Limited | Professional & scientific | 2016 |
| TWENTY9 Properties Limited | Real estate | 2020 |
| Twig Construction Group Limited | Construction | 2017 |
| Twilight Financial Consulting Ltd | Information & communication | 2011 |
| Twin Tulip Ltd | Professional & scientific | 2025 |
| Twins TV Limited | Information & communication | 2011 |
| Twist & Pout Limited | Other services | 2017 |
| Two Become One Wedding Planner Ltd | Other services | 2020 |
| Two N Four Productions Limited | Information & communication | 2004 |
| Twok Cosmetics Ltd | Manufacturing | 2016 |
| TXS Digital Ltd | Professional & scientific | 2022 |
| TY Estates Ltd | Real estate | 2020 |
| Tye's Mastic Ltd | Construction | 2026 |
| Tylers Elite Finishing Limited | Construction | 2021 |
| Tylers Elite Properties Limited | Construction | 2025 |
| Tylon IT Services Ltd | Information & communication | 2025 |
| Tynlace Limited | Construction | 2020 |
| Tyrell Investments Limited | Professional & scientific | 2024 |
| Tyrell Place Management Company Limited | Extraterritorial | 2010 |
| Tyrezone Distribution Limited | Wholesale & retail | 2026 |
| Tyrone Shoelaces Ltd | Information & communication | 2016 |
| U.K. Hajj & Umrah Services Ltd | Administrative & support | 2002 |
| UB Academy LDN Ltd | Education | 2019 |
| UCS Group Ltd | Professional & scientific | 2022 |
| UDM Properties Limited | Real estate | 2001 |
| Ufuk Catering Ltd | Hospitality | 2023 |
| Ugoogbukamarshall Services Limited | Construction | 2019 |
| Ujja Ltd | Real estate | 2023 |
| UK Automotive Ltd | Wholesale & retail | 2007 |
| UK Cooling and Heating Services Ltd | Construction | 2020 |
| UK Flooring Subbies Ltd | Construction | 2020 |
| UK Football Camps Limited | Arts & recreation | 2014 |
| UK Heavyplant Hire Limited | Administrative & support | 2016 |
| UK Line Ltd | Construction | 2021 |
| UK LPG Ltd | Construction | 2016 |
| UK Port Express Ltd | Transport & logistics | 2022 |
| UK Quality Cars Ltd | Wholesale & retail | 2024 |
| UK Salads Limited | Wholesale & retail | 2004 |
| UK Salads Partners LLP | | 2021 |
| UK Vehicle Recycling Ltd | Water & waste | 2016 |
| UKA Sports Ltd | Education | 2022 |
| Ukbioscienceco Ltd | Wholesale & retail | 2026 |
| Ukflipzone Ltd | Wholesale & retail | 2026 |
| Ukpin Ltd | Administrative & support | 2020 |