| TGT Oilfield Services UK Limited | Aberdeen | 2012 |
| Thames Nonferrous Metals Co. Ltd. | St. Andrews | 2018 |
| Thatcher Properties Limited | New Milton | 2004 |
| THD Beauty Limited | Topsham | 2017 |
| THE Africa Mining Company Ltd | London | 2020 |
| THE Americas Bancor Investment Limited | London | 2024 |
| THE Asset Integrity Consultants Ltd. | Bolton | 2020 |
| THE Atlas RAW Materials Corporation Ltd | Accrington | 2025 |
| THE Bacup Clay Company Limited | Blackpool | 2015 |
| THE British Borneo Company Limited | | 2004 |
| THE Charnwood Quarrying and Recycling Company Limited | Meriden | 2024 |
| THE Commodity Resources Ltd | Bournemouth | 2025 |
| THE Delabole Slate Company Limited | Cornwall | 1999 |
| THE Dorothea Lakes Ltd | Old Hatfield | 1991 |
| THE ELK Group Ltd | Reading | 2017 |
| THE Euro Mediterranean Company of Intelligent Trade Ltd | Cardiff | 2021 |
| THE Flint Trader Ltd | Castle Eden | 2025 |
| THE GEO People Ltd | Hereford | 2005 |
| THE Goldy One Limited | London | 2025 |
| THE Highfield Mineral Company Ltd | Bradford | 2022 |
| THE Horsham Stone Co Ltd | Horsham | 2026 |
| THE Irish Mint Limited | Newry | 2026 |
| THE Mineral Company Ltd. | Yeovil | 2022 |
| THE Mining Legacy Consultancy Limited | Alfreton | 2015 |
| THE Old Pier Braaishack Ltd | Stonehaven | 2024 |
| THE Old Red Quarry Limited | Crewe | 2021 |
| THE Parkmead Group PLC | London | 2000 |
| THE Paving Works Limited | London | 2025 |
| THE Petroleum and Renewable Energy Company Limited | Ascot | 1999 |
| THE Potters Clay & Coal Co. Limited | Etruria Stoke On Trent | 1935 |
| THE Potting Shed Minerals Limited | Truro | 2024 |
| THE Quasarrr Ltd | Southend-On-Sea | 2025 |
| THE Rolling Stock & Engineering Co. Limited | Portsmouth | 1923 |
| THE State of BIR Tawil Ltd | Thornton Heath | 2021 |
| THE Y. a. Group Holdings (UK) Ltd | London | 2023 |
| THE Yorkshire Mining Company Limited | Wakefield | 2017 |
| THE Yorkstone Paving Company Ltd | Salford | 2020 |
| Theodore Foundation Ltd | Leicester | 2014 |
| Thermalume Services Limited | Norwich | 2014 |
| Thesaurum Gold Exploration Ltd. | St. Neots | 2020 |
| Thesaurum Ltd. | St. Neots | 2020 |
| Thine Group Limited | London | 2017 |
| Think Energy International Ltd | Esher | 2020 |
| Third Energy UK GAS Limited | Great Yarmouth | 1979 |
| Thistle Well Engineering Ltd | Montrose | 2017 |
| Thomas Crompton Quarries Limited | Bradford | 2019 |
| Thomas Scourfield & Sons | Swansea | 1999 |
| Thombo Petroleum Ltd | London | 2004 |
| Thompson Construction and Access Ltd | Wingate | 2019 |
| Thompson RIG and Welding Services Limited | Huntingdon | 2016 |
| Thompson Subsea Services Ltd | Aberdeen | 2016 |
| Thompson's International Tubing Services Ltd | Newcastle Upon Tyne | 2009 |
| Thomson Access Solutions Ltd | Inverness | 2014 |
| Thomson Onshore Offshore Specialist Limited | Auldearn | 2016 |
| Thomson Subsea Ltd | Montrose | 2008 |
| Thorogood Consultants | Insch | 2007 |
| Thoth Mining Ltd | London | 2025 |
| Three Way Global Ltd | London | 2023 |
| THREE60 Energy Consulting Limited | Aberdeen | 2024 |
| THREE60 Energy Wells UK Holdings Limited | Aberdeen | 2015 |
| THREE60 Energy Wells UK Limited | Aberdeen | 1991 |
| THREE60 Integrity Management Limited | Aberdeen | 2021 |
| Threlkeld Quarry Museum Limited | Keswick | 2006 |
| Thrower Construction Limited | Great Yarmouth | 2011 |
| Thrupple Holdings Limited | London | 2020 |
| Tianzi Global Limited | London | 2024 |
| Tide Table Logistics Ltd | Congleton | 2025 |
| Tidswell Electrical Services Ltd. | Helensburgh | 2023 |
| Tiga Ikan Subsea Services Limited | Stonehaven | 2010 |
| Tigerrose Energy Limited | Huntly | 2015 |
| Tillicoultry Quarries (EA) Limited | Kings Lynn | 1986 |
| Tillicoultry Quarries Limited | Alloa | 1931 |
| Tillicoultry Quarries Mortars and Renders Ltd | Alloa | 2018 |
| TIM Herrett Limited | Manningtree | 2000 |
| TIMBUK3 Projects Ltd. | Dunblane | 2011 |
| Time Line International Limited | Colchester | 2000 |
| Tinto Sand and Gravel Limited | Lanarkshire | 1957 |
| Titan OIL Ltd | London | 2017 |
| Titsey Estate Company(The) | Horsham | 1927 |
| Tizir Limited | London | 2011 |
| TJ Geophysics Limited | Buckingham | 2012 |
| Tjgx Ltd | Esher | 2015 |
| TJS Aggregates Ltd | Boston | 2017 |
| TL O&G Services Ltd | Lowestoft | 2025 |
| TLA Subsea Ltd | Montrose | 2020 |
| TLR Construction Ltd | Barrow In Furness | 2024 |
| TLS Supply Ltd | London | 2024 |
| Tmag OIL & GAS U.K., Ltd. | Woking | 2014 |
| TMB Electrical Services Ltd | Blackpool | 2019 |
| TMC the Metals Company UK Limited | London | 2021 |
| Tmech Services Ltd | Blyth | 2025 |
| TNG Geophysics Limited | Cranbrook | 2017 |
| TOB Company (UK) Limited | London | 2017 |
| Tollymore Services Ltd | Ballymena | 2020 |
| Tolwide Limited | Tynemouth | 1989 |
| TOM Jervis Limited | Dunfermline | 2016 |
| Tomaknock Services Limited | Crieff | 2019 |
| Tomas Fryda Ltd | Blackpool | 2019 |
| Tomax Drilling Technology UK Limited | Aberdeen | 2014 |
| Tomdoun Limited | Balgownie Road, Bridge Of Don | 2017 |