| Top Performance Consulting Limited | Arts & recreation | 2010 |
| Topaz Marine Services Limited | Arts & recreation | 1982 |
| Torwell Limited | Real estate | 2003 |
| Total Event Impact Ltd | Professional & scientific | 2026 |
| Total Relaxation Limited | Other services | 2022 |
| Totally RAD Music Limited | Education | 2014 |
| Totally RAD Schools Limited | Information & communication | 2020 |
| Totem Worldwide Ltd | Professional & scientific | 2025 |
| Toucantech Limited | Information & communication | 2013 |
| Tour Britannia Ltd | Transport & logistics | 2024 |
| Town & Country Scaffolding (Banbury) Limited | Construction | 1996 |
| Town and Country Pubs Ltd | Hospitality | 2019 |
| Tracey Cooper Ltd | Arts & recreation | 2021 |
| Trad-Ac Therapies Limited | Health & social care | 2017 |
| Trade Secret (Home Improvements) Limited | Construction | 2003 |
| Trade Vehicle Sales Ltd | Wholesale & retail | 2025 |
| Trafalgar Hire Ltd | Construction | 2011 |
| Trandaspeed Ltd | Professional & scientific | 2018 |
| Transform Coaching & Training Ltd | Education | 2019 |
| Transformation Space Ltd | Education | 2015 |
| Trcr Holdings Ltd | Wholesale & retail | 2012 |
| Trcr Ltd | Wholesale & retail | 2025 |
| Trex Construction Limited | Other services | 2008 |
| TRH Holdings Limited | Financial services | 2026 |
| Triangle Information Management (Holding) Ltd | Information & communication | 2022 |
| Trillium Engineering Group Limited | Professional & scientific | 2024 |
| Trilogy Plus Ltd | Construction | 2018 |
| Trim Property Ltd | Real estate | 2019 |
| Trinity Court Healthcare Limited | Wholesale & retail | 2026 |
| Triple R Tyres Limited | Wholesale & retail | 2020 |
| Tristam Hand Plastering Ltd | Construction | 2017 |
| Trub Trub Ltd | Professional & scientific | 2018 |
| True Interior Developments Ltd | Construction | 2022 |
| True Tech LAB Ltd | Wholesale & retail | 2026 |
| Trustnest Living Ltd | Real estate | 2025 |
| TS Faith Limited | Real estate | 2023 |
| Tsfc Limited | Hospitality | 2024 |
| TTB Engineering Limited | Professional & scientific | 2006 |
| Ttbd Ltd | Professional & scientific | 2017 |
| Tudor Oak Construction Holberrow Green Ltd | Construction | 2019 |
| Tuffley Park Management Company Limited | Households | 2012 |
| TUI Legal Ltd | Professional & scientific | 2026 |
| Turaco Healthcare Limited | Health & social care | 2019 |
| Tusc Energy Ltd | Professional & scientific | 2017 |
| Tusc Limited | Professional & scientific | 2005 |
| Twenty 885 Limited | Professional & scientific | 2020 |
| Twenty Two Eleven Ltd | Professional & scientific | 2023 |
| Twinstream Holdings Ltd | Information & communication | 2022 |
| Twinstream Limited | Information & communication | 2018 |
| Twist Interiors Limited | Professional & scientific | 2004 |
| Twisted Fish IT Limited | Information & communication | 2011 |
| Two Hats Theatre Company Ltd | Information & communication | 2005 |
| Two Mango Trees Ltd | Professional & scientific | 2013 |
| TWS Partners Limited | Professional & scientific | 2017 |
| TWT Web DEV Ltd | Professional & scientific | 2021 |
| TXB Consulting Ltd | Information & communication | 2009 |
| Tye-Smith Electrical Services Ltd | Manufacturing | 2023 |
| TYM Tractors UK Ltd | Wholesale & retail | 2011 |
| U F Solutions Limited | Health & social care | 2016 |
| Ugly Nail Ltd | Other services | 2025 |
| UK Consulting Services Ltd | Professional & scientific | 2023 |
| UK Ground Screws Limited | Construction | 2018 |
| UK Integrity Ltd | Administrative & support | 2011 |
| Ukgs Solutions Ltd | Manufacturing | 2008 |
| Ultimate Garden Rooms Ltd | Manufacturing | 2021 |
| Unbreakable Promotions Ltd | Arts & recreation | 2021 |
| Uncorked Rebellion Ltd | Wholesale & retail | 2026 |
| Understanding Care (Coventry) Limited | Health & social care | 2014 |
| Understanding Care (Extra Care) Limited | Health & social care | 2014 |
| Understanding Care (Holdings) Limited | Professional & scientific | 2015 |
| Understanding Care (Warwickshire) Limited | Health & social care | 2011 |
| Unicorn Cars Ltd | Transport & logistics | 2014 |
| Unique Custom Ltd | Professional & scientific | 2016 |
| Unique Sector Performance Data Ltd | Information & communication | 2016 |
| Unity Automotive Leicester Limited | Wholesale & retail | 2013 |
| Unity Automotive Oxford Limited | Wholesale & retail | 2014 |
| Unity Automotive Peterborough Limited | Wholesale & retail | 2010 |
| Universal Automotive Services Limited | Construction | 2023 |
| Universal Card & Coin Ltd | Extraterritorial | 2023 |
| Universal Freight Organisation Limited | Other services | 2000 |
| Uplyft Workers Ltd | Information & communication | 2026 |
| Upon-A-Van Conversions Ltd | Wholesale & retail | 2025 |
| Upper Acres (Ettington) Management Company Limited | Households | 2017 |
| Upper Langley Consulting Limited | Professional & scientific | 2012 |
| Upper Langley Homes (Honeybourne) Ltd | Construction | 2026 |
| Upper Langley Homes Limited | Construction | 2019 |
| Urbanshire Limited | Administrative & support | 2019 |
| Uroboros Ensemble Limited | Arts & recreation | 1982 |
| USA Padel Directory Ltd | Information & communication | 2024 |
| Usha Bangladeshi & Indian Cuisine Limited | Hospitality | 2026 |
| USP Data Ltd | Information & communication | 2016 |
| Utilitech Power Ltd | Professional & scientific | 2019 |
| UVC Displays Limited | Manufacturing | 2015 |
| UYA Limited | Real estate | 2026 |
| V & a Webb Ltd | Extraterritorial | 2012 |
| V H Training Limited | Professional & scientific | 2007 |
| V K V Management Ltd | Professional & scientific | 2018 |
| V&C Collectables Ltd | Wholesale & retail | 2025 |
| Vada Studios Limited | Information & communication | 2012 |
| Valhal Limited | Financial services | 2021 |