| Trafford Private Hire Limited | Transport & logistics | 2003 |
| Trafford Rowing Club Limited | Arts & recreation | 2016 |
| Train Safe Wipes Ltd | Manufacturing | 2025 |
| Training for English Language Teachers Ltd | Education | 2008 |
| Training Ground Guru Ltd | Information & communication | 2017 |
| Training Qualifications UK Ltd | Education | 2011 |
| Transfer Bunny (Luton) Ltd | Transport & logistics | 2025 |
| Transmanian Devils RFC Ltd | Arts & recreation | 2023 |
| Transnational Press London Ltd. | Information & communication | 2013 |
| Tranzio Ltd | Wholesale & retail | 2025 |
| Travelingweb Ltd | Information & communication | 2017 |
| Trearddur Bay FC Holding Co Ltd | Financial services | 2024 |
| Trearddur Bay FC Ltd | Arts & recreation | 2024 |
| Trearddur Bay FC Prop Co Ltd | Real estate | 2024 |
| TRI Plus Financial Ltd | Financial services | 2021 |
| Trimfast Limited | Wholesale & retail | 1963 |
| Trimurti Properties Limited | Real estate | 2024 |
| Trinidad Endoscopy Limited | Health & social care | 2017 |
| Trinity Business Centre Ltd | Other services | 2009 |
| Trinity Facilities Limited | Construction | 2017 |
| Trinity Fresh and Clean Limited | Administrative & support | 2025 |
| Trinity Homes and Lettings Ltd | Real estate | 2025 |
| Trinity Iconic Properties Limited | Real estate | 2017 |
| Trippin&Sippin Ltd | Administrative & support | 2024 |
| Tristan Brodbeck Financial Planning Ltd. | Professional & scientific | 2012 |
| Tristone Group Ltd | Financial services | 2017 |
| Tristone Healthcare Limited | Financial services | 2015 |
| Tristone Healthcare Properties 2 Limited | Health & social care | 2023 |
| Tristone Healthcare Properties Limited | Health & social care | 2023 |
| Tristone SSS Holdings Limited | Financial services | 2019 |
| Triumph UK Management Ltd | Real estate | 2020 |
| Trojan CT (Morley) RTM Co Ltd | Extraterritorial | 2026 |
| Trueface ID Ltd | Wholesale & retail | 2018 |
| Truly Marketing Limited | Professional & scientific | 2010 |
| Trust UC Ltd | Wholesale & retail | 2023 |
| Trusted Planning Limited | Financial services | 2010 |
| TSP Electrical Limited | Construction | 2023 |
| Ttbn Property Ltd | Real estate | 2021 |
| Tuitupou Limited | Arts & recreation | 2012 |
| Tunga Consulting Limited | Information & communication | 2017 |
| Turkmany (London) Ltd | Wholesale & retail | 2019 |
| Turret Orthodontics Limited | Health & social care | 2010 |
| Tuskie's Pet Foods Limited | Wholesale & retail | 2025 |
| TVB (Clifton) Ltd | Real estate | 2022 |
| Tvtc Ltd | Information & communication | 2018 |
| TWENTY23 Group Limited | Administrative & support | 2025 |
| Twinkle Domestic Services Limited | Other services | 2010 |
| Twinkle House Limited | Health & social care | 2007 |
| Twinkle Toes Holdings UK Ltd | Financial services | 2020 |
| Twist Infusions Limited | Wholesale & retail | 2015 |
| Twisted Running Ltd | Wholesale & retail | 2020 |
| TWJ Partnership LLP | | 2003 |
| TWJ Personal Limited | Professional & scientific | 2002 |
| Two Four Nine Studios Limited | Information & communication | 2024 |
| Two Tribes Ltd | Hospitality | 2021 |
| TX Group Ltd | Health & social care | 2008 |
| Tycoon Ltd | Real estate | 2025 |
| Tyler Burke Ltd | Wholesale & retail | 2026 |
| Tyres Warehouse Ltd | Wholesale & retail | 2025 |
| Tysc Limited | Professional & scientific | 2019 |
| Tystech Ltd | Professional & scientific | 2024 |
| U-Uk Study Ltd | Education | 2013 |
| Ubuntu HR Ltd | Administrative & support | 2011 |
| Ugozel Estates Ltd | Real estate | 2019 |
| UK Accommodation OPS 1 Limited | Hospitality | 2021 |
| UK Accommodation OPS Limited | Administrative & support | 2015 |
| UK Gift Card & Voucher Association | Other services | 2015 |
| UK Legal and Consultant Service Center Limited | Professional & scientific | 2016 |
| UK Print.Com Ltd | Manufacturing | 2024 |
| UK Property Platform Ltd | Real estate | 2018 |
| UK Renal Pathology Limited | Education | 2020 |
| UK Sustainable Flooring Alliance Limited | Water & waste | 2007 |
| UK17 Consultancy Limited | Administrative & support | 2017 |
| UKFOOD43 Limited | Hospitality | 2025 |
| UKS Health Group Limited | Administrative & support | 2003 |
| Ulsa Ventures Limited | Real estate | 2025 |
| Ultraturn Engineering Limited | Professional & scientific | 2015 |
| Under Productions Limited | Information & communication | 2012 |
| Underground Retail Ltd | Wholesale & retail | 2002 |
| Underground Surveys (UK) Limited | Professional & scientific | 2009 |
| Unico Studio Ltd | Other services | 2026 |
| Unicorn Tech Limited | Wholesale & retail | 2019 |
| Unicou Ltd | Education | 2023 |
| Unique Pointing Ltd | Construction | 2016 |
| Unique Spa Sale NW Ltd | Health & social care | 2018 |
| Unissu Ltd | Information & communication | 2018 |
| United Grill Limited | Hospitality | 2023 |
| United Insolvency Ltd | Financial services | 2018 |
| United Languages Ltd | Professional & scientific | 2018 |
| United Ultimate Home Land Security Ltd | Administrative & support | 2010 |
| United WE Stand Limited | Information & communication | 1997 |
| Unity Psychology Services Limited | Health & social care | 2025 |
| Universal Products Group Limited | Wholesale & retail | 2016 |
| Untangled Business Limited | Professional & scientific | 2025 |
| Untangled Insight Ltd | Professional & scientific | 2024 |
| UP North Air Conditioning Ltd | Construction | 2021 |
| UP North Media Limited | Information & communication | 2017 |
| Upkey Ltd | Health & social care | 2022 |
| UPM Group Ltd | Professional & scientific | 2008 |
| Urban Axis Ltd | Real estate | 2026 |