| Tudor Properties (Peterborough) Ltd | Peterborough | 2003 |
| Tulcan Energy Resources UK Ltd. | London | 2017 |
| Tullochbeg Ltd | London | 2016 |
| Tullow Argentina Limited | London | 2019 |
| Tullow Côte D'Ivoire Onshore Limited | London | 2016 |
| Tullow Group Services Limited | London | 2005 |
| Tullow New Ventures Limited | London | 2016 |
| Tullow OIL Finance Limited | London | 2012 |
| Tullow OIL PLC | London | 2000 |
| Tullow OIL SK Limited | London | 2004 |
| Tullow OIL SPE Limited | London | 2002 |
| Tullow Peru Limited | London | 2017 |
| Tullow Uruguay Limited | London | 2012 |
| Tullyraine Quarries, Limited | Banbridge | 1958 |
| Tundra-X Gold Corporation Ltd | London | 2020 |
| Tungex Limited | Birmingham | 2026 |
| Tungsten Energy Ltd | Harlow | 2023 |
| Tungsten West Services Limited | Plympton | 2020 |
| Tunnel Engineering Solutions Limited | Pontypridd | 2021 |
| Turnbull Services Ltd. | Banff | 2005 |
| Turner Offshore Services Limited | Bedlington | 2018 |
| Turquoise Marine Services Limited | Kingston Upon Thames | 2020 |
| Turuk OIL and GAS Development Co Ltd | Glasgow | 2018 |
| TUS UR Ltd | Enniskillen | 2026 |
| Tusker Resources Limited | Sheffield | 2019 |
| Tutum Resources Limited | London | 2015 |
| Tuya Energia Ltd | Much Wenlock | 2025 |
| TVK Cementing Oil&Gas Ltd | Galashiels | 2026 |
| Twed Consultancy Limited | Cleveland | 2015 |
| Twin Metals (UK) Limited | London | 2010 |
| Twmmcorporation Ltd | Barking | 2021 |
| TY Mawr West Limited | Porthmadog | 2004 |
| Tyson Geoscience Limited | Reading | 2013 |
| TZR BLK Limited | Leeds | 2022 |
| U.K. Discovery Limited | Mansfield | 1998 |
| U.K. GAS Limited | Bridgend | 1991 |
| U.K. Methane Limited | Bridgend | 1997 |
| Ubaggregates Ltd | Inverness | 2020 |
| Ubique Offshore Ltd | South Shields | 2026 |
| Uhuru Energy Ltd | London | 2022 |
| UJU Holdings Limited | | 2002 |
| UK (Bemander) Chemical Industry Group Co., Ltd | London | 2025 |
| UK 3B Bios Limited | Cambridge | 2025 |
| UK Afonor International Group Co., Ltd | Cardiff | 2026 |
| UK Africa Trading Ltd | Cardiff | 2025 |
| UK Aibon Plant Health Co., Ltd | Cambridge | 2026 |
| UK Airanshi Chemical Group Limited | London | 2023 |
| UK Alpha Crop Health Alliance Limited | Stafford | 2021 |
| UK Amais Specialty Crop Nutrition Co., Ltd | Cambridge | 2024 |
| UK Ambili Crop Protection Co., Ltd | Cambridge | 2025 |
| UK Ampus (Plant Protection) Ltd | West Midlands, England | 2025 |
| UK Asynon Chemical Co., Ltd | Cambridge | 2025 |
| UK Atofina Chemistry Limited | Thames Ditton | 2017 |
| UK Badro International Chemical Group Co., Ltd | Cardiff | 2026 |
| UK Bailis Nutrition Co., Ltd | Cambridge | 2025 |
| UK Bairui Petrochemical Co., Ltd | London | 2022 |
| UK Bamlang International Chemical Co., Ltd | Cardiff | 2026 |
| UK Baozhifeng Technology Services Co., Ltd | Beckenham | 2024 |
| UK Basf Plant Nutrition Research Center Limited | Beckenham | 2023 |
| UK Beike Biological Development Technology Ltd | Beckenham | 2023 |
| UK Besis Plant Nutrition Co., Ltd | West Midlands, England | 2026 |
| UK Bezier Special Fertilizer Co., Ltd | Cardiff | 2023 |
| UK Bioom Limited | Cambridge | 2021 |
| UK Biotop Botanical Science Ltd | Cobham | 2020 |
| UK Bitan International Group Co., Ltd | Cambridge | 2025 |
| UK Bittan International Group Co. Ltd | Beckenham | 2021 |
| UK Blatt Crop Nutrition Co., Ltd | Cambridge | 2025 |
| UK Bostoun Crop Technology Co., Ltd | Cardiff | 2025 |
| UK Cadi Yinglun Crop Nutrition Group Co., Ltd | Coventry | 2024 |
| UK Calvin Plant Health Ltd | Cambridge | 2021 |
| UK Cambridge Horns Specialty Fertilizer Co., Ltd | London | 2025 |
| UK Cartec Petroleum International Limited | West Midlands, England | 2023 |
| UK Chemical Group Limited | West Midlands, England | 2026 |
| UK Chempley Chemical Co., Ltd | Cardiff | 2026 |
| UK Cossimi Chemical Co., Ltd | Cambridge | 2024 |
| UK Dawei International Group Co., Ltd | Beckenham | 2022 |
| UK Delishi Special Fertilizer Co., Ltd | Cardiff | 2021 |
| UK Dika Pioneer International Chemical Group Co., Ltd | Cambridge | 2025 |
| UK Dinok Crop Science Ltd | Coventry | 2025 |
| UK Dorf Ketal Chemical Ltd | Beckenham | 2022 |
| UK Drlex Petrochemical Co., Ltd | Beckenham | 2024 |
| UK Dyer Crops Co., Ltd | Beckenham | 2023 |
| UK Dyson International Chemical Ltd | Beckenham | 2022 |
| UK Earth Radius Group Development Limited | Manchester | 2025 |
| UK Elephant Cattle Limited | Beckenham | 2022 |
| UK Engbo Plant Protection Co., Ltd | Cambridge | 2026 |
| UK Epson Crop Protection Co., Ltd | Cambridge | 2025 |
| UK Epts Limited | Reading | 2021 |
| UK Euomate Agrochemicals Co., Ltd | Cambridge | 2025 |
| UK Faraday Plant Protection International Co., Ltd | Cardiff | 2026 |
| UK Felix Biotechnology Co., Ltd | Cardiff | 2026 |
| UK Felter International Chemical Co., Ltd | London | 2025 |
| UK Fenghe Green Source Nutritional Agriculture Technology Co., Ltd | London | 2025 |
| UK Ferndale International Group Co., Ltd | Cardiff | 2026 |
| UK Filtek Biotechnology Co., Ltd. | London | 2025 |
| UK Fuerguo Plant Nutrition Co., Ltd | Cambridge | 2024 |
| UK Fusi Mining Chemcial Ltd | West Midlands | 2023 |
| UK Geluoliya Biology Technology Ltd | Cambridge | 2024 |
| UK Geothermal Ltd | London | 2021 |
| UK Gnamuinternational Chemical Co., Ltd | Bristol | 2026 |