| Trans LPC Ltd | Transport & logistics | 2025 |
| Trans-Pav Ltd | Transport & logistics | 2015 |
| Transconfort Ltd | Wholesale & retail | 2019 |
| Transformation Dynamics Ltd | Professional & scientific | 2025 |
| Transhipment Terminals Ltd | Transport & logistics | 2024 |
| Transnet Properties Ltd | Real estate | 2019 |
| Transport Hub and Services Ltd | Transport & logistics | 2024 |
| Travel Abroad Consultancy Limited | Professional & scientific | 2026 |
| Travelcup Ltd | Administrative & support | 2025 |
| Travelway Ltd | Administrative & support | 2002 |
| Traylens Amusements Limited | Arts & recreation | 1949 |
| Treehouse SJ Ltd | Administrative & support | 2025 |
| Treelogy Holdings Ltd | Financial services | 2024 |
| Trendatcom Ltd | Information & communication | 2026 |
| Trending Girl Ltd | Wholesale & retail | 2024 |
| Trevi Suppliers Limited | Wholesale & retail | 2004 |
| Trexon Trade Ltd | Wholesale & retail | 2024 |
| Trim Tabbers Publications Limited | Information & communication | 2013 |
| Triple a Motoring Ltd | Wholesale & retail | 2025 |
| Triple H Builders Ltd | Construction | 2023 |
| Tripple A28 Ltd | Real estate | 2024 |
| Tripseasons Ltd | Administrative & support | 2024 |
| Trishna Wellbeing Limited | Health & social care | 2024 |
| Triton Property Holdings Limited | Real estate | 2025 |
| Trivia Consultants Ltd | Professional & scientific | 2026 |
| TRS Building Contractors Ltd | Construction | 2025 |
| TRS Management & Consultancy (UK) Limited | Professional & scientific | 2017 |
| Trssk Trading Company Ltd | Wholesale & retail | 2024 |
| Tru-It Solutions Limited | Information & communication | 2025 |
| True Blue Interiors Ltd | Construction | 2014 |
| True Line One Ltd | Construction | 2026 |
| True Technologies Ltd | Information & communication | 2025 |
| Trusted Homecare (NW) Limited | Health & social care | 2020 |
| Truwino Bakehouse Ltd | Manufacturing | 2025 |
| Trycon Limited | Information & communication | 2025 |
| Tryilluminate Ltd | Wholesale & retail | 2025 |
| TS Cater & Dine Ltd | Hospitality | 2016 |
| TS Property Solutions Ltd | Hospitality | 2016 |
| TS Success Ltd | Professional & scientific | 2018 |
| TSK Peri Peri Ltd | Hospitality | 2026 |
| Tsunami Stream Limited | Information & communication | 2009 |
| Turning Tricks Limited | Extraterritorial | 2003 |
| Tutordemy Ltd | Education | 2025 |
| Tutoring Champions Ltd | Education | 2024 |
| Twentysevenagar Limited | Households | 2016 |
| TWG Tea Limited | Wholesale & retail | 2010 |
| Twin and Earth Electrics Ltd | Construction | 2016 |
| TWM Holding Limited | Financial services | 2025 |
| Tyres Shop Limited | Wholesale & retail | 2014 |
| U Cioci Limited | Wholesale & retail | 2013 |
| U K Shutters & Glass Ltd | Construction | 2011 |
| U&K Restaurants Ltd | Hospitality | 2025 |
| UB on Safari Limited | Administrative & support | 2012 |
| UB6 Cars Ltd | Wholesale & retail | 2023 |
| Uban Limited | Wholesale & retail | 2022 |
| UBI Capital Ltd | Real estate | 2026 |
| Ucher Body Repair Ltd | Wholesale & retail | 2020 |
| UEZ Enterprises Ltd | Real estate | 2022 |
| UK Chauffeur Services Limited | Transport & logistics | 1999 |
| UK Chauffeuring Ltd | Transport & logistics | 2025 |
| UK Dragon and Lion Dance Federation | Arts & recreation | 2024 |
| UK Education Center Ltd | Real estate | 2018 |
| UK Express Ltd | Wholesale & retail | 2015 |
| UK Foods London Ltd | Wholesale & retail | 2011 |
| UK Hybrid Automotive Limited | Wholesale & retail | 2017 |
| UK Hybrid Car Hire Ltd | Administrative & support | 2022 |
| UK London Car Limited | Wholesale & retail | 2023 |
| UK Pioneering Education Ltd | Education | 2024 |
| UK Portal Ltd | Wholesale & retail | 2020 |
| UK Real Estate Investment Trust Limited | Extraterritorial | 2004 |
| UK Real Estate Limited | Construction | 1986 |
| UK Trade Enterprises Ltd | Wholesale & retail | 2012 |
| UK Trip Travels Limited | Administrative & support | 2025 |
| Ukorium Ltd | Construction | 2022 |
| Ukrfixcom Construction Limited | Construction | 2023 |
| Uktn Logistics Ltd | Transport & logistics | 2025 |
| Ultimate Management Ltd | Professional & scientific | 2018 |
| Ultimate Property Contractors Ltd | Construction | 2013 |
| Ultimate Retail Group Ltd | Wholesale & retail | 2016 |
| Ultiquest Ltd | Information & communication | 2024 |
| Ultra AI Ltd | Information & communication | 2019 |
| Ultramax Batteries Limited | Wholesale & retail | 2012 |
| Umami Digital Solutions Ltd | Information & communication | 2020 |
| UMI Says Ltd | Wholesale & retail | 2018 |
| UMT Limited | Hospitality | 2010 |
| Uncle's Gourmet Limited | Hospitality | 2018 |
| Underwood Miller Ltd | Arts & recreation | 2020 |
| Unibal Property Investment Ltd | Real estate | 2022 |
| Unigize Ltd | Information & communication | 2019 |
| Unikove Technologies Limited | Information & communication | 2018 |
| Union House Properties(Billericay)Limited | Real estate | 1972 |
| Unique City Solutions Ltd | Administrative & support | 2014 |
| Unique Construction (London) Limited | Construction | 2004 |
| Unique NTA Ltd | Wholesale & retail | 2019 |
| Unit 8 Transport Services Ltd | Wholesale & retail | 2021 |
| United Cater Limited | Wholesale & retail | 2012 |
| United Kitchens & Bedrooms Limited | Manufacturing | 2025 |
| United Nepali Revival Church Limited | Other services | 2019 |
| Unitedshipper Ltd | Wholesale & retail | 2024 |
| Unity Partners UK Ltd | Hospitality | 2024 |