| Thedevhub Ltd | Administrative & support | 2021 |
| Theertha News Agents Ltd | Wholesale & retail | 2024 |
| Thefrogg Ltd | Hospitality | 2025 |
| Thejus Eats Ltd | Hospitality | 2023 |
| Thejus Food UK Ltd | Wholesale & retail | 2020 |
| Theolytics Ltd | Professional & scientific | 2017 |
| Therapy Spot Limited | Education | 2018 |
| Therapywithcare Ltd | Health & social care | 2023 |
| Thermofuture Limited | Professional & scientific | 2023 |
| Things Go Wild Ltd | Wholesale & retail | 2018 |
| Think-Ug Care Ltd | Health & social care | 2023 |
| Thinkahead Oxford Limited | Professional & scientific | 2024 |
| Thinkbright Research Ltd | Professional & scientific | 2023 |
| Thinkegic Tech Ltd | Information & communication | 2025 |
| Thinkers Meet UP Limited | Education | 2021 |
| Third Strand Consulting Limited | Professional & scientific | 2013 |
| Thirness Limited | Real estate | 1980 |
| Thirsty Meeples Ltd | Administrative & support | 2012 |
| This Great Adventure Ltd | Information & communication | 2021 |
| This IS Language Ltd | Education | 2011 |
| This IS School Limited | Education | 2023 |
| This Means Waaagh LLP | | 2023 |
| Thiskrit Ltd | Information & communication | 2025 |
| Thom Airs Media Ltd | Information & communication | 2021 |
| Thomas Fairfax Limited | Real estate | 2009 |
| Thomas Fairfax NO 2 Limited | Extraterritorial | 2009 |
| Thomas Merrifield Abingdon Limited | Real estate | 1997 |
| Thomas Merrifield Bicester Limited | Real estate | 1996 |
| Thomas Merrifield Didcot Limited | Real estate | 1997 |
| Thomas Merrifield Kidlington Limited | Real estate | 1997 |
| Thomas Merrifield Newbury Limited | Real estate | 2023 |
| Thomas Merrifield Oxford Limited | Real estate | 1996 |
| Thomas Merrifield Wallingford Limited | Real estate | 1999 |
| Thomas Merrifield Wantage Limited | Real estate | 2006 |
| Thomas Merrifield Witney Limited | Real estate | 2000 |
| Thomas Weissensteiner Ltd | Professional & scientific | 2022 |
| Thomas White Oxford Life Sciences Limited | Construction | 2023 |
| Thomas White Oxford Limited | Construction | 2015 |
| Thomas White Properties Limited | Real estate | 2012 |
| Thomson Cleaning Ltd | Administrative & support | 2018 |
| Thomson Terrace Allotments C.I.C. | Agriculture & fishing | 2023 |
| Thor Investments Limited | Real estate | 2007 |
| Thorne Coaching & Consulting Limited | Professional & scientific | 2019 |
| Thorne Coaching Limited | Professional & scientific | 2019 |
| Thornhill & Co. LLP | | 2015 |
| Thoth UK Limited | Professional & scientific | 1999 |
| Thoughtful Electron Ltd | Professional & scientific | 2025 |
| Thousand Years Music Ltd | Information & communication | 2020 |
| Three Cumnor Hill (Oxford) Management Company Limited | Households | 2007 |
| Three Harmony Group Ltd | Hospitality | 2025 |
| Three Horse Shoes 2020 Ltd | Hospitality | 2020 |
| Three Idle Women LLP | | 2025 |
| Three Lanterns Management Limited | Real estate | 1995 |
| Three Link Projects Limited | Information & communication | 2008 |
| Threesixty Commercial Catering Ltd | Wholesale & retail | 2023 |
| Threesixtywellbeing Ltd | Health & social care | 2021 |
| Thrift Developments Limited | Financial services | 1985 |
| Thrive Care Services Limited | Health & social care | 2017 |
| Thrive Consulting Limited | Wholesale & retail | 2015 |
| Thrive Properties International Limited | Real estate | 2018 |
| Thrivegrad Ltd | Professional & scientific | 2025 |
| Thrum Leadership Ltd | Professional & scientific | 2021 |
| Thrupp Canal Cruising Club Limited | Other services | 1996 |
| Thurston Hamblin LLP | | 2018 |
| THW Management Limited | Real estate | 2026 |
| THY Spa Ltd | Other services | 2016 |
| Thyme BIO Ltd | Professional & scientific | 2023 |
| TI Automotive (China) Limited | Professional & scientific | 2000 |
| TI Automotive Canada Holdings Limited | Professional & scientific | 2005 |
| TI Automotive Czech Holdings (UK) Limited | Professional & scientific | 2007 |
| TI Automotive Finance Limited | Professional & scientific | 2002 |
| TI Automotive German Holdings (UK) Limited | Professional & scientific | 2007 |
| TI Automotive Holdings Limited | Professional & scientific | 2001 |
| TI Automotive Korean WON Hedgeco II Limited | Professional & scientific | 2005 |
| TI Automotive Korean WON Hedgeco Ltd | Professional & scientific | 2015 |
| TI Automotive Limited | Professional & scientific | 2000 |
| TI Automotive Pension Plan Trustee Limited | Professional & scientific | 2001 |
| TI Education Services Ltd | Education | 2016 |
| TI Fluid Systems Limited | Professional & scientific | 2015 |
| TI Group Automotive Systems (Deeside) Limited | Administrative & support | 1995 |
| TI Group Automotive Systems (UK) Limited | Manufacturing | 1963 |
| TI Group Automotive Systems Limited | Administrative & support | 1957 |
| Tiara Properties Ltd | Real estate | 2016 |
| Tiara Property Holdings Limited | Real estate | 2019 |
| Tick Tock Social Limited | Professional & scientific | 2013 |
| Ticktock Games Limited | Information & communication | 2007 |
| Tiddly Pommes Ltd | Manufacturing | 2016 |
| Tidy Touch Services Ltd | Administrative & support | 2023 |
| Tieetdye Ltd | Wholesale & retail | 2019 |
| Tifs Holdings Limited | Professional & scientific | 2009 |
| Tigerdale Limited | Financial services | 2013 |
| Tigers at Bowood Nursery School Limited | Education | 2005 |
| Tigers at Swindon Limited | Education | 2015 |
| Tigers at Theale Limited | Education | 2001 |
| Tigers Day Nursery Limited | Education | 2000 |
| Tigers Print Limited | Manufacturing | 2021 |
| Tigers Training Centre Limited | Education | 2011 |
| Tigershark Ltd | Information & communication | 2004 |
| Tiki Homes Ltd | Real estate | 2020 |
| Tile Elysium Ltd | Construction | 2025 |