| TRH Limited | Real estate | 2001 |
| TRI Castle Investments Limited | Financial services | 2001 |
| Trimmers Field (Farnham) Management Company Limited | Households | 1987 |
| Trimmers Field Management Company Limited | Real estate | 2017 |
| Trimming Close Management Company Limited | Households | 2018 |
| Trimming Willis & Co. Limited | Real estate | 1939 |
| Trinity Environmental Ltd | Construction | 2020 |
| Trinovantum Media Limited | Information & communication | 2021 |
| Triple FUN Chinese Language School Limited | Education | 2021 |
| Triple Threat Security Ltd | Administrative & support | 2017 |
| Triride GM Ltd | Wholesale & retail | 2018 |
| Triton Synergies Limited | Professional & scientific | 2016 |
| Trivera Process Safety Ltd | Professional & scientific | 2026 |
| Trojan Build & Labour Limited | Construction | 2024 |
| True Summit Adventures Ltd | Administrative & support | 2022 |
| True to Yourself Pilates Ltd | Arts & recreation | 2023 |
| Trustcore Services Ltd | Construction | 2020 |
| Truvista Consulting Limited | Professional & scientific | 2003 |
| TS Office Services Ltd | Professional & scientific | 2010 |
| Tsml Consulting Ltd | Information & communication | 2023 |
| TT Construction Solutions Limited | Construction | 2011 |
| Ttph Ltd | Health & social care | 2015 |
| Tucker Stone Limited | Professional & scientific | 2009 |
| Tuckwell Chase Lottery Limited | Arts & recreation | 1998 |
| Tudor Alexander Ltd | Professional & scientific | 2013 |
| Tudor Court (Farnborough) Management Company Limited | Administrative & support | 1987 |
| Tudor Court Estates Limited | Households | 1987 |
| Tudor Rose Investments Ltd | Real estate | 2025 |
| Tudor Williams (Holdings) Limited | Financial services | 2004 |
| Tudor Williams Limited | Wholesale & retail | 1938 |
| Tukal Limited | Real estate | 2014 |
| Turner DEE Limited | Professional & scientific | 2017 |
| Turner Landscaping Ltd | Administrative & support | 2018 |
| Turnstone AV Ltd | Wholesale & retail | 2013 |
| Tutor House by Alefredo UK Limited | Education | 2026 |
| Tutors Ltd | Education | 2026 |
| TVA Consultancy Limited | Real estate | 2026 |
| Tweedmount Consulting Limited | Professional & scientific | 2016 |
| Twelve at Greenacre Ltd | Households | 2019 |
| Tweseldown Limited | Real estate | 2014 |
| Twist Contract Flooring Limited | Construction | 2019 |
| Two Point Lighting Ltd | Information & communication | 2016 |
| Two Stones Solutions Ltd | Administrative & support | 2023 |
| Two Thirds Water Limited | Information & communication | 2009 |
| Two Wombats Limited | Wholesale & retail | 2023 |
| Tychetools Group Ltd | Administrative & support | 2020 |
| Tyhurst Place (Andover) Management Company Limited | Households | 2010 |
| Tyler Bale Limited | Professional & scientific | 2011 |
| Tyler-Jones Ltd | Information & communication | 2013 |
| Tylney Wood Management Limited | Real estate | 2000 |
| Typhoon Investments Limited | Transport & logistics | 2017 |
| Tytherington Investments Limited | Real estate | 1960 |
| U Beauty Limited | Other services | 2003 |
| Uber Haus Design Ltd | Professional & scientific | 2015 |
| Ucan Training Limited | Professional & scientific | 2007 |
| UD Cars Limited | Wholesale & retail | 2024 |
| Uflex Cars Ltd | Transport & logistics | 2026 |
| UK AOA Company Limited | Manufacturing | 2020 |
| UK Business Brokers Ltd | Professional & scientific | 2026 |
| UK Construction Management Ltd | Construction | 2024 |
| UK Grid Connections Limited | Construction | 2022 |
| UK Lanyard Makers Ltd | Manufacturing | 2014 |
| UK Pool Lifts Ltd | Wholesale & retail | 2004 |
| UK Renewables & Ventilation Ltd | Construction | 2023 |
| UK REP MED Limited | Administrative & support | 2017 |
| UK Stay Ltd | Hospitality | 2005 |
| UK Welding Supplies Ltd | Wholesale & retail | 2023 |
| Ukph Limited | Construction | 2020 |
| Ullswater Consulting Limited | Professional & scientific | 2025 |
| Ultimate Wargames Limited | Wholesale & retail | 2015 |
| Ultra Property Services Ltd | Construction | 2021 |
| Ultranza Ltd | Information & communication | 2012 |
| Ultraurora Limited | Wholesale & retail | 2021 |
| Unco Global Asset Management Agency Ltd | Mining & quarrying | 2010 |
| Uncommon Stuff Limited | Administrative & support | 2016 |
| Underlined Limited | Professional & scientific | 2023 |
| Unicorn Orange Ltd | Professional & scientific | 2020 |
| Unifect Ltd | Wholesale & retail | 2002 |
| Unimed Electrode Supplies Limited | Health & social care | 2006 |
| UNION4PLANNING Limited | Professional & scientific | 2017 |
| Unit Supply Ltd | Information & communication | 2023 |
| Unitchase Property Management Limited | Households | 1989 |
| United Healthcare Limited | Professional & scientific | 1996 |
| United Healthcare Services Limited | Professional & scientific | 1996 |
| United Kingdom Lettings Limited | Extraterritorial | 2017 |
| United Kingdom Properties Limited | Real estate | 2015 |
| Univale Consultants Limited | Professional & scientific | 2004 |
| Universal Stock Limited | Wholesale & retail | 2012 |
| Unleashed K9 Adventures Ltd | Other services | 2021 |
| Unshuffled Ltd | Information & communication | 2022 |
| Upper Bourne Piping Ltd | Professional & scientific | 2026 |
| Upper Church Lane Barbers Ltd | Other services | 2017 |
| Upper Hale Holdings Limited | Financial services | 2021 |
| Upper Hale Road Land Limited | Households | 2022 |
| Upstream Capital Limited | Professional & scientific | 2012 |
| Urban Place LAB Limited | Professional & scientific | 2016 |
| Urban Space LAB Limited | Extraterritorial | 2019 |
| Urban Spaceman Storage Limited | Real estate | 2013 |
| Uvex Safety (UK) Ltd | Wholesale & retail | 1988 |
| UYS Sports Design Ltd | Professional & scientific | 2024 |