| Twenty-Seven Seventeen Limited | Education | 2025 |
| Twentyfour IT Services Limited | Information & communication | 2014 |
| TWH Limited | Professional & scientific | 2025 |
| Twinbeacons Security Ltd | Extraterritorial | 2026 |
| Twinkle Twinkle Boutique Ltd | Wholesale & retail | 2018 |
| Twinn Aerosystems Limited | Information & communication | 2001 |
| Twinplant Limited | Construction | 2022 |
| Twins HQ Ltd | Other services | 2026 |
| Twisted Broom Ltd | Arts & recreation | 2022 |
| Twisted Fate Limited | Other services | 2023 |
| Twisted Scissors Hair Co. Doncaster Limited | Other services | 2025 |
| Twisted Vines Active Ltd | Education | 2021 |
| Two Counties Vets Limited | Professional & scientific | 2011 |
| Two JAR Consultancy Limited | Professional & scientific | 2025 |
| Two Oaks Property Solutions Ltd | Real estate | 2025 |
| Twotrees Outdoors Ltd | Wholesale & retail | 2025 |
| TWR Inc Ltd | Wholesale & retail | 2025 |
| TWW Services Limited | Extraterritorial | 2015 |
| TX Insight Limited | Information & communication | 2025 |
| TX Production Limited | Extraterritorial | 2015 |
| Tybus Ltd | Administrative & support | 2022 |
| Typrint Limited | Manufacturing | 2008 |
| Tyram Resorts Ltd | Construction | 2014 |
| Tyranrex Ltd | Transport & logistics | 2023 |
| Tyre Clinic U.K. Limited | Wholesale & retail | 2019 |
| Tyre Torque Doncaster Limited | Wholesale & retail | 2012 |
| Tyres 2 Go Doncaster Limited | Wholesale & retail | 2022 |
| Tyresathome Ltd | Extraterritorial | 2024 |
| U and I Servicing Limited | Construction | 2024 |
| U-KNOW3 Limited | Administrative & support | 2020 |
| U-Store (Doncaster) Limited | Other services | 2008 |
| U.K Swift Group Limited | Construction | 2022 |
| U.K. Diamjewel Limited | Manufacturing | 2004 |
| U.K. Fixings Limited | Wholesale & retail | 1999 |
| U.K. Garage Services Limited | Extraterritorial | 2002 |
| U.K.V.S. Limited | Administrative & support | 2003 |
| UBB Waste (Essex) Limited | Water & waste | 2012 |
| Uber Access Ltd | Construction | 2016 |
| Ubique Business Services Limited | Administrative & support | 2007 |
| Ubique Consultancy Ltd | Construction | 2023 |
| Ucabdoncaster Ltd | Transport & logistics | 2022 |
| Ucars Ltd | Wholesale & retail | 2013 |
| Udrea Transport Ltd | Transport & logistics | 2021 |
| UFH Systems & Spares Limited | Wholesale & retail | 2025 |
| Uipw Ltd | Administrative & support | 2025 |
| Ujrn Ltd | Wholesale & retail | 2020 |
| UK & European Auctions Ltd | Wholesale & retail | 2024 |
| UK Bargainland Ltd | Wholesale & retail | 2025 |
| UK Cosmetic Surgery Limited | Health & social care | 2018 |
| UK Energi Ltd | Construction | 2022 |
| UK Estate and Property Management Ltd | Real estate | 2019 |
| UK FJ Homes Ltd | Real estate | 2026 |
| UK Modular Buildings Ltd | Construction | 2013 |
| UK Optical Services Ltd | Health & social care | 2011 |
| UK Pipeline Supplies Ltd | Construction | 2016 |
| UK Plumbing & Training Services Limited | Wholesale & retail | 2006 |
| UK Polymer Solutions Limited | Wholesale & retail | 2015 |
| UK Postal Competition Ltd | Information & communication | 2026 |
| UK Slimming Club Ltd | Health & social care | 2025 |
| UK Surety Ltd | Financial services | 2011 |
| UK Swift Electrical Ltd | Construction | 2023 |
| UK Trade Global Ltd | Wholesale & retail | 2021 |
| UK USA Eliquids Ltd | Wholesale & retail | 2016 |
| UK Vintage Furniture Ltd | Extraterritorial | 2014 |
| Uk-Euro Property Limited | Construction | 2002 |
| UKA Decor Garden Limited | Construction | 2024 |
| Ukfabrics Limited | Wholesale & retail | 2022 |
| Ukfalcon Commercial Ltd | Wholesale & retail | 2023 |
| Ukforte 2021 Ltd | Financial services | 2022 |
| Ukforte 2022 Ltd | Financial services | 2022 |
| Ukforte Ltd | Financial services | 2020 |
| Ukhb Support Services Limited | Water & waste | 2025 |
| Ukrp Ltd | Wholesale & retail | 2021 |
| Uktrade 2020LTD Limited | Construction | 2023 |
| Ukwelder Ltd. | Wholesale & retail | 2001 |
| Ulitransport Limited | Transport & logistics | 2024 |
| Ulmax Limited | Transport & logistics | 2019 |
| Ulmus Homes Limited | Construction | 2023 |
| Ulstertal - Komplettservice UND BAU Limited | Professional & scientific | 2006 |
| Ultima Cars Limited | Wholesale & retail | 2017 |
| Ultimate Automotive Works Ltd | Wholesale & retail | 2023 |
| Ultimate Image Limited | Information & communication | 2020 |
| Ultimate International Limited | Administrative & support | 1999 |
| Ultimate Kennls UK Ltd | Wholesale & retail | 2025 |
| Ultimate Pest Control Ltd | Administrative & support | 2025 |
| Ultra Commerce Ltd | Wholesale & retail | 2022 |
| Ultra Controls Limited | Professional & scientific | 2025 |
| Ultra Tiling Ltd | Construction | 2019 |
| Ultrimax Coatings Limited | Manufacturing | 2013 |
| Ultrimax Holdings Limited | Financial services | 2020 |
| UMA Hotel Limited | Hospitality | 2010 |
| Umaxstar Ltd | Wholesale & retail | 2025 |
| Umberllaproperties Limited | Real estate | 2020 |
| Ummi Wholesale Ltd | Wholesale & retail | 2025 |
| UMP Ltd | Other services | 2012 |
| UN Food Limited | Hospitality | 2022 |
| Unauthorised Limited | Arts & recreation | 2013 |
| Unbloq Ltd | Professional & scientific | 2014 |
| Uncle Eddies Cafe Ltd | Arts & recreation | 2017 |
| Uncle Eddies Enduro | Arts & recreation | 2011 |