| Treetop Learning Ltd | Education | 2015 |
| Tremaine & Nala Limited | Real estate | 2025 |
| Trevor Martin Developments Ltd. | Construction | 2007 |
| Trew Solutions Ltd | Professional & scientific | 2024 |
| Trex 2 Limited | Arts & recreation | 2018 |
| TRI County Fire Limited | Construction | 2018 |
| Tri-Bar Customs Ltd | Manufacturing | 2019 |
| Tri-Counties Heating Ltd | Construction | 2018 |
| Tribal Media Ltd | Information & communication | 2024 |
| Tribe Fibre Ltd | Information & communication | 2023 |
| Trident Exterior Cleaning Ltd | Administrative & support | 2024 |
| Trident Offshore Projects Ltd | Extraterritorial | 2018 |
| Triggerlabs Limited | Professional & scientific | 2018 |
| Trinity Tooling & Machinery Ltd | Manufacturing | 2018 |
| Trinity Whitehouse Management Limited | Households | 2006 |
| Triple 3 Foster Care Limited | Administrative & support | 2026 |
| Triple 3 Healthcare Group Limited | Administrative & support | 2022 |
| Triple F Services Limited | Wholesale & retail | 2015 |
| Triplek Cleaning Solution Ltd | Administrative & support | 2022 |
| Triton Acquisitions Ltd | Real estate | 2017 |
| Triton Advisory Limited | Professional & scientific | 2018 |
| Triton Private Wealth Limited | Financial services | 2025 |
| Trout Tool Co,Limited | Manufacturing | 1957 |
| Troy Automotive Ltd | Professional & scientific | 2025 |
| Trpi Ltd. | Real estate | 1999 |
| Trsl Limited | Extraterritorial | 2021 |
| Trucker Logistics Ltd | Transport & logistics | 2021 |
| True Lotus Ltd | Hospitality | 2025 |
| Truenorth Health Ltd | Wholesale & retail | 2026 |
| Truglaze Windows Limited | Construction | 2009 |
| Trulo Ltd | Information & communication | 2024 |
| Trusence Ltd | Real estate | 2019 |
| Truss PR Limited | Professional & scientific | 2021 |
| TS International Solutions Limited | Administrative & support | 2006 |
| TSB Arboriculture Services Ltd | Administrative & support | 2024 |
| TSG Music Limited | Education | 2012 |
| TSR Avilane Limited | Information & communication | 2026 |
| TSS Developments Limited | Construction | 2025 |
| Tucker Tech Limited | Information & communication | 2020 |
| Tuna Ltd | Transport & logistics | 2025 |
| Turaida Capital Ltd | Wholesale & retail | 2026 |
| Turf N' Power Ltd | Administrative & support | 2021 |
| Turneround Design Services Ltd | Professional & scientific | 2013 |
| Turnstyle CIC | Education | 2023 |
| Turtle & Co Limited | Real estate | 1999 |
| Turuva Limited | Hospitality | 2025 |
| Twelve Frognal Gardens Residents Association Limited | Households | 1974 |
| Twenty 20 Architecture Limited | Professional & scientific | 2017 |
| Twenty 20 Technical Limited | Professional & scientific | 2018 |
| Twenty 20 Vision Limited | Professional & scientific | 2017 |
| TWG Automotive Limited | Wholesale & retail | 2011 |
| TWH Associates (UK) Ltd | Professional & scientific | 2014 |
| Twisted Deli Limited | Manufacturing | 2024 |
| TWK Pest Limited | Administrative & support | 2026 |
| Twmpa Limited | Extraterritorial | 2011 |
| Two Swans Content Ltd | Other services | 2021 |
| Two Twenty Studio Limited | Professional & scientific | 2019 |
| Tymm Properties Limited | Real estate | 2020 |
| Tyne Flooring Limited | Real estate | 1965 |
| Type 23 Limited | Financial services | 2021 |
| Tyrefitterslondon Limited | Wholesale & retail | 2025 |
| Tyser Greenwood Limited | Extraterritorial | 2021 |
| U K Heritage Construction Ltd | Construction | 2025 |
| U Services Limited | Information & communication | 2016 |
| U.S. Rent a Car Limited | Administrative & support | 2003 |
| UBR Holdings (UK) Limited | Professional & scientific | 2016 |
| UF International Limited | Wholesale & retail | 2012 |
| Uhlmann U.K. Limited | Manufacturing | 1999 |
| UK Bangla Tigers Cricket Club CIC | Arts & recreation | 2025 |
| UK Business Advisors Ltd | Professional & scientific | 2004 |
| UK Commercial Cleaning Limited | Administrative & support | 2023 |
| UK Homezone Ltd | Real estate | 2025 |
| UK Lifesaver Limited | Wholesale & retail | 2018 |
| UK Motorzone Ltd | Wholesale & retail | 2016 |
| Ukba Ltd | Professional & scientific | 2008 |
| Ukdn Ltd | Information & communication | 2019 |
| UKH Consultancy Ltd | Construction | 2020 |
| Umbrella Connect Ltd | Administrative & support | 2019 |
| Umbrella Property Management Limited | Real estate | 2021 |
| Unafortis Ltd | Professional & scientific | 2026 |
| Unibright Logistics Ltd | Transport & logistics | 2009 |
| Unicarval Properties Limited | Real estate | 2023 |
| Unify Energy Partners Limited | Professional & scientific | 2024 |
| Unify Group (Emea) Limited | Professional & scientific | 2013 |
| Unify Integrated Solutions Limited | Information & communication | 2024 |
| Union Building (Aldershot) Residents Company Limited | Households | 2012 |
| Unique Builders & Groundworks Ltd | Construction | 2022 |
| Unique Five Ltd | Wholesale & retail | 2016 |
| Unique Roofing & Upvc Ltd | Construction | 2022 |
| Unique Views Limited | Real estate | 2021 |
| Uniquip Uniforms Limited | Manufacturing | 1992 |
| United Christian Activists Ltd | Information & communication | 2026 |
| Universal Vacation Club Properties Limited | Professional & scientific | 1997 |
| University Mansions RTM Company Limited | Real estate | 2008 |
| Univolt (UK) Limited | Wholesale & retail | 1990 |
| Unleeshed Ltd. | Professional & scientific | 2024 |
| Untapped Growth LLP | | 2025 |
| UP Football Academy Ltd | Education | 2025 |
| Uplift Social Limited | Information & communication | 2024 |
| Upper Gordon Road (Camberley) Management Company Limited | Households | 2014 |