| TU Productions Ltd | Information & communication | 2023 |
| Tudor Borehamwood Limited | Hospitality | 2022 |
| Tudorsound Limited | Information & communication | 2013 |
| Tudy Cosmetics Ltd | Manufacturing | 2019 |
| Tudy Parfums Ltd | Administrative & support | 2016 |
| Tughra Catering Ltd | Hospitality | 2016 |
| Tumulus Productions Ltd | Information & communication | 2024 |
| Tunlo Ltd | Wholesale & retail | 2025 |
| Turismotec Ltd | Professional & scientific | 2000 |
| Turnberry House Limited | Real estate | 2021 |
| Turtlestep Ltd | Extraterritorial | 2013 |
| Turtlewings Limited | Professional & scientific | 2022 |
| Tutu Diagnostics Ltd | Wholesale & retail | 2021 |
| TUX Properties Ltd | Real estate | 2024 |
| TV & Film Research Ltd | Information & communication | 2010 |
| Tvday Limited | Information & communication | 2016 |
| TVJ Ltd | Manufacturing | 2018 |
| Twelve-By-Seventy-Five Limited | Professional & scientific | 2014 |
| Twelves Corporation Limited | Professional & scientific | 2023 |
| Twenty One Eighty Seven Limited | Other services | 2014 |
| TWENTY2E Limited | Construction | 2022 |
| TWENTY7 Publicity Limited | Professional & scientific | 2014 |
| Twentyeight Track (Residential) Limited | Real estate | 2021 |
| Twentyeight Track Limited | Real estate | 2016 |
| Twin Tech Repair Ltd | Wholesale & retail | 2025 |
| Twin V Ltd | Arts & recreation | 2016 |
| Twinkletoes Productions Limited | Arts & recreation | 2014 |
| Twinmar Limited | Wholesale & retail | 1963 |
| Twistbox Entertainment (UK) Limited | Administrative & support | 2005 |
| Twistbox Games Limited | Administrative & support | 2004 |
| Two Candles (Online) Limited | Information & communication | 1999 |
| Twothree Creative Ltd | Arts & recreation | 2023 |
| Tydd Resource Centre Consult Limited | Information & communication | 2007 |
| Tydus Peterborough LLP | | 2022 |
| Tydus Real Estate Limited | Real estate | 2017 |
| Tydwood Investments Limited | Real estate | 2022 |
| TYH Consultants Ltd | Professional & scientific | 2021 |
| TYH Growth Partners Limited | Financial services | 2024 |
| TYH1 a Limited | Real estate | 2022 |
| TYH1 Limited | Real estate | 2020 |
| TYH2 Limited | Real estate | 2022 |
| Typica Limited | Wholesale & retail | 2015 |
| Tzur Ltd | Wholesale & retail | 2015 |
| Tête Blanche Limited | Professional & scientific | 2022 |
| U&U Construction Ltd | Construction | 2014 |
| U'Luvka Ltd | Manufacturing | 2013 |
| UEM UK Limited | Real estate | 2025 |
| Ugochukwu Marcus Ltd | Other services | 2019 |
| UK Addiction Treatment Limited | Health & social care | 2012 |
| UK Bargains 74 Ltd. | Hospitality | 2014 |
| UK Building Construction Limited | Construction | 2007 |
| UK Businessbuddy Limited | Professional & scientific | 2018 |
| UK Display & Awnings Ltd | Construction | 2011 |
| UK Expert Builder Ltd | Construction | 2024 |
| UK Facades Limited | Construction | 2009 |
| UK Foods Trading Limited | Wholesale & retail | 2007 |
| UK Foot & Ankle Ltd | Health & social care | 2024 |
| UK Langley Surfacing Limited | Construction | 2015 |
| UK Newswire Ltd | Information & communication | 2024 |
| UK Research & Innovation Limited | Other services | 2023 |
| UK Smile Ltd | Health & social care | 2007 |
| UK Toremet Limited | Health & social care | 2010 |
| Ukara Properties Ltd | Real estate | 2022 |
| Ukat Group Limited | Financial services | 2024 |
| Ukat Investments Limited | Financial services | 2018 |
| Ukat Online Ltd | Professional & scientific | 2018 |
| Ukea Holdings Limited | Professional & scientific | 2019 |
| Ukinvest Properties Ltd | Real estate | 2025 |
| Ukivc (UK Immigration and Visa Consultancy) LLP | | 2025 |
| Uler Limited | Transport & logistics | 2014 |
| Ulteria Limited | Arts & recreation | 2012 |
| Ultimate Plumbing Limited | Construction | 2021 |
| Uluvka(London) Limited | Manufacturing | 2020 |
| UMA Property Investments Limited | Real estate | 2023 |
| Umezushi Ltd | Hospitality | 2014 |
| Umutu Development Association UK Ltd | Health & social care | 2025 |
| Under the Arches Limited | Real estate | 2014 |
| Unico Recruitment (London) Ltd | Administrative & support | 2026 |
| Unidoor Ltd | Construction | 2014 |
| Uniled Software Limited | Information & communication | 2017 |
| Unimount Ltd | Information & communication | 2022 |
| Uniplus Telecom Ltd | Information & communication | 2015 |
| Unique Asset Management Limited | Professional & scientific | 2010 |
| Unison Media Limited | Professional & scientific | 1999 |
| Unit 7 Elstree Building Management Company Limited | Real estate | 2009 |
| Unita Properties Ltd | Real estate | 2025 |
| United Forms Limited | Administrative & support | 2015 |
| United Housing Limited | Real estate | 2022 |
| United Relations Advocacy CIC | Health & social care | 2025 |
| United Vending Gym (UK) Ltd | Hospitality | 2018 |
| United Visual Artists Limited | Administrative & support | 2002 |
| Unity Hertsmere Ltd | Education | 2025 |
| Universal Medecs Ltd | Health & social care | 2005 |
| Universal Smart Cards Limited | Manufacturing | 2001 |
| Universal Star Listing Limited | Wholesale & retail | 1995 |
| Universal Supply Group Limited | Wholesale & retail | 2023 |
| Univibe Social Limited | Administrative & support | 2017 |
| Unleash Academy UK Limited | Professional & scientific | 2025 |
| Unleash Your S.E.X.Y. Ltd | Wholesale & retail | 2021 |
| Unlimited Toast and Spread Ltd | Professional & scientific | 2024 |