| THE Resilience Forge Ltd | Professional & scientific | 2024 |
| THE Right Fit Ltd | Health & social care | 2015 |
| THE Sidings (Cholsey) Management Company Limited | Households | 2002 |
| THE Street Wallingford (Flats) Management Company Limited | Households | 2012 |
| THE Three Horseshoes (Benson) Limited | Hospitality | 2022 |
| THE Together Agency Limited | Administrative & support | 2006 |
| THE Treehouse Trust | Education | 2011 |
| THE UK Fieldwork Company Limited | Professional & scientific | 2008 |
| THE Wallingford Bookshop Ltd | Wholesale & retail | 2021 |
| THE Wallingford Masonic Centre Limited | Other services | 1998 |
| THE Wallingford Tearoom Ltd | Hospitality | 2018 |
| THE Wandering Kitchen Limited | Hospitality | 2013 |
| THE Wild Baker Limited | Hospitality | 2014 |
| THE Wilder Woods Co Ltd | Information & communication | 2025 |
| THE Wildlife Survey Unit Limited | Administrative & support | 2009 |
| Think Waste Recycling Limited | Water & waste | 2016 |
| Thirlwall Associates Ltd | Professional & scientific | 2003 |
| Thirty Seven Productions Limited | Arts & recreation | 2012 |
| Thisistogetherzero Ltd | Professional & scientific | 2021 |
| Thomas Consulting and Engineering Ltd | Professional & scientific | 2017 |
| Thomas Jones Cabinet Makers Ltd | Manufacturing | 2025 |
| Thorney Park Golf Limited | Arts & recreation | 2002 |
| Thorpdown Limited | Information & communication | 1996 |
| Three Bears Childcare Ltd | Health & social care | 2024 |
| Three Hearts & Coleman Ltd | Real estate | 2026 |
| Tilson Garden Ltd | Hospitality | 2024 |
| TIM O'Hare Associates LLP | | 2006 |
| Tjfry Ltd | Professional & scientific | 2026 |
| TK Lanes Consultancy Limited | Health & social care | 2021 |
| TK Wong Limited | Wholesale & retail | 2025 |
| TMD Workshop Supplies Limited | Other services | 2019 |
| Toddler Town Early Years Ltd | Health & social care | 2026 |
| Tohonesty Limited | Wholesale & retail | 2024 |
| TOM Cook Plumbing & Heating Limited | Construction | 2021 |
| TOM W Ayling Ltd | Wholesale & retail | 2024 |
| Tomlinso Ltd | Professional & scientific | 2019 |
| Tonibobandlou C.I.C. | Professional & scientific | 2023 |
| Toolindata Ltd | Information & communication | 2025 |
| Tooth World Ltd | Extraterritorial | 2025 |
| Topiary Studio Ltd | Information & communication | 2024 |
| Topzzle Ltd | Manufacturing | 2025 |
| Total Metalworks Holdings Limited | Financial services | 2017 |
| Total Metalworks Ltd | Manufacturing | 2011 |
| Touchstone Planning & Development Ltd | Professional & scientific | 2012 |
| Towers Hair Ltd | Other services | 2013 |
| Town & Country Telecommunications Limited | Information & communication | 2009 |
| TR Wallingford Ltd | Hospitality | 2026 |
| Tracy Jarvis International Ltd | Information & communication | 2024 |
| Trading Equity Limited | Real estate | 2004 |
| Trailrun Ltd | Information & communication | 2022 |
| Travale Limited | Extraterritorial | 2006 |
| Tred-Ad Ltd | Professional & scientific | 2014 |
| Tree Doctor (Oxfordshire) Limited | Other services | 2021 |
| Treehouse Trading Cholsey Limited | Wholesale & retail | 2025 |
| Treleaven Luxury Cornish Ice Cream Limited | Hospitality | 2011 |
| Treveo Ltd | Professional & scientific | 2010 |
| Tri-Vector Capital Limited | Financial services | 2019 |
| Triaster Ltd | Information & communication | 1994 |
| Trojan Home Improvements Limited | Construction | 2018 |
| Trust for Oxfordshire's Environment (TOE) Ltd | Education | 2011 |
| Tucasi Limited | Information & communication | 2004 |
| Tuilcean Ltd | Professional & scientific | 2017 |
| Turville Montessori Limited | Education | 2013 |
| TVR Garage Limited | Wholesale & retail | 2026 |
| TW Timberwork Ltd | Construction | 2012 |
| Twigs and Tails Education CIC | Education | 2025 |
| UK Centre for Ecology & Hydrology | Other services | 2018 |
| UK Centre for Ecology & Hydrology Enterprise Limited | Professional & scientific | 2019 |
| UK Centre for Ecology & Hydrology International Limited | Professional & scientific | 2024 |
| UK Field Work Services Limited | Professional & scientific | 1999 |
| UK Information Technology Limited | Information & communication | 2015 |
| Ultimatum Health Limited | Health & social care | 2025 |
| Uncommon Counsel Limited | Professional & scientific | 2026 |
| United PIG Co-Operative Ltd. | Agriculture & fishing | 1975 |
| Uniware Systems Limited | Information & communication | 1994 |
| Upper Grange Estate Ltd | Extraterritorial | 2014 |
| Urban Eco Limited | Professional & scientific | 2009 |
| Urban-Fx Ltd. | Wholesale & retail | 2002 |
| Urbanoasis Properties Limited | Real estate | 2023 |
| Uvio Commercial (Broadway) Ltd | Real estate | 2010 |
| Uvio Commercial (Hurlingham) Ltd | Real estate | 2019 |
| Uvio Commercial Ltd | Financial services | 2016 |
| Uvio Group Limited | Financial services | 2021 |
| Uvio Ltd | Administrative & support | 2007 |
| Uwatch Limited | Information & communication | 2015 |
| Vangus Ltd | Information & communication | 2020 |
| VB Writing Ltd | Professional & scientific | 2019 |
| Veloviecc Ltd | Wholesale & retail | 2022 |
| Ventus Automotive Ltd | Wholesale & retail | 2020 |
| Ver-Components Ltd | Wholesale & retail | 2019 |
| Verdec Fencing Ltd | Construction | 2019 |
| Vertical Drop Limited | Information & communication | 2025 |
| Verto Consultancy Limited | Professional & scientific | 2005 |
| Vertus Group UK Holdco Limited | Information & communication | 2026 |
| Verwood Skelhorn Consulting Ltd | Professional & scientific | 2026 |
| Vesta Merchant Services Limited | Administrative & support | 2009 |
| Vesta Payroll Ltd | Information & communication | 2002 |
| Vesta Software Group Limited | Administrative & support | 2012 |
| Veterinary Advisors Ltd | Professional & scientific | 2012 |
| Victor and Delilah Limited | Manufacturing | 2022 |