| THE Waste Brokerage Company Ltd | Water & waste | 2019 |
| THE Water ZOO Limited | Wholesale & retail | 2014 |
| THE Weekend Cleaning Company Ltd | Administrative & support | 2019 |
| THE White Cat Company Limited | Information & communication | 2012 |
| THE Willbe Company Limited | Professional & scientific | 1992 |
| THE Willows Woodcote Close Management Company Limited | Households | 2008 |
| THE Windmill Restaurant Ltd | Hospitality | 2026 |
| THE Winners S Agencies Limited | Administrative & support | 2015 |
| THE Woolly Beers Ltd | Hospitality | 2025 |
| THE Worx Nutrition Limited | Arts & recreation | 2025 |
| THE Yard Castor Ltd | Hospitality | 2023 |
| THE Young Performers Academy CIC | Education | 2026 |
| The-Nest-Group Ltd | Construction | 2016 |
| Thegreencycle Ltd | Information & communication | 2023 |
| Thehackspace Ltd C.I.C. | Hospitality | 2019 |
| Themarketspace Ltd | Wholesale & retail | 2022 |
| Themeware Limited | Information & communication | 1995 |
| Themotion Ltd | Wholesale & retail | 2026 |
| Theo Micoud Ltd | Information & communication | 2026 |
| Theomat Ltd | Health & social care | 2025 |
| Thephonefixers Ltd | Wholesale & retail | 2018 |
| Therashalom Group Ltd | Public administration | 2022 |
| Thermascan Limited | Administrative & support | 1995 |
| Thesnagcompany Ltd | Professional & scientific | 2022 |
| Thesocialbutterflies Limited | Information & communication | 2024 |
| Thespinner Ltd | Wholesale & retail | 2025 |
| Thesquiduk Limited | Information & communication | 2023 |
| Thessy Logistics Limited | Transport & logistics | 2023 |
| Theta Property Limited | Real estate | 2019 |
| Thetaxlab Ltd | Professional & scientific | 2022 |
| Thetford Farm Estate Limited | Real estate | 2021 |
| Thetford Management Company Limited | Households | 2015 |
| Thewayoftheweb Limited | Information & communication | 2012 |
| Theworkline Ltd | Administrative & support | 2020 |
| Thfh Ltd | Financial services | 2021 |
| Thhg Limited | Health & social care | 2010 |
| Think 21 Ltd | Other services | 2025 |
| Think Home Fascias Limited | Wholesale & retail | 2019 |
| THINK3DPRINT3D Limited | Financial services | 2012 |
| Thinktanc Limited | Information & communication | 2024 |
| Thinkterns Ltd | Information & communication | 2013 |
| Third EYE 7 Limited | Financial services | 2024 |
| Third Heritage Fellowship | Other services | 2021 |
| Thirsk Residents Company Limited | Households | 2005 |
| Thistle Fire and Security Limited | Administrative & support | 2007 |
| Thistle Psychiatry Ltd | Wholesale & retail | 2026 |
| Thistle Thread Ltd | Wholesale & retail | 2024 |
| Thistlemoor Healthcare & Management Limited | Real estate | 2004 |
| Thistlemoor Smiles Centre Limited | Health & social care | 2025 |
| Thistles by VCK Ltd | Wholesale & retail | 2015 |
| Thistles Cashmere Ltd | Wholesale & retail | 2020 |
| Thistles Golf Ltd | Wholesale & retail | 2025 |
| Thobani Accountants Ltd | Professional & scientific | 2020 |
| Thomas & Co (Consultants) Limited | Professional & scientific | 2012 |
| Thomas & Thomas Management Services Limited | Professional & scientific | 2000 |
| Thomas Ackroyd Limited | Administrative & support | 1957 |
| Thomas Bishop Consulting Limited | Professional & scientific | 2024 |
| Thomas Cook Airlines Leasing Limited | Transport & logistics | 2017 |
| Thomas Cook Brands Limited | Hospitality | 2018 |
| Thomas Cook Finance Limited | Administrative & support | 2007 |
| Thomas Cook Group Hedging Limited | Administrative & support | 2012 |
| Thomas Cook Hotel Management Limited | Hospitality | 2018 |
| Thomas Cook Indian IP Limited | Administrative & support | 2012 |
| Thomas Cook Investments 3 Limited | Administrative & support | 2017 |
| Thomas Cook Pension Trust Limited | Professional & scientific | 1979 |
| Thomas Cook Treasury Limited | Administrative & support | 2000 |
| Thomas Cook West Holdings Limited | Administrative & support | 2014 |
| Thomas Deacon Education Trust | Education | 2004 |
| Thomas Hill Lettings Limited | Real estate | 2022 |
| Thomas Hill Sales and Lettings Ltd | Real estate | 2015 |
| Thomas Seffi Ltd | Health & social care | 2014 |
| Thompson Agri Limited | Professional & scientific | 2025 |
| Thompson and James Sugar Partners Limited | Administrative & support | 2020 |
| Thompson and Randall Construction Ltd | Construction | 2026 |
| Thompson Plant Energy Ltd | Manufacturing | 2026 |
| Thompsons Yard Limited | Households | 2021 |
| Thomson Fraser Ltd | Financial services | 2014 |
| Thor Holdings Limited | Wholesale & retail | 2019 |
| Thor Motor Factors Limited | Wholesale & retail | 1987 |
| Thorburn Landscapes Limited | Administrative & support | 2014 |
| Thorne Air Conditioning Limited | Manufacturing | 1996 |
| Thorney Beck Nurseries Ltd | Agriculture & fishing | 2022 |
| Thorney Market Ltd | Wholesale & retail | 2025 |
| Thorney Phase 2 Management Company Limited | Households | 2023 |
| Thorney Properties Ltd | Real estate | 2024 |
| Thorney Tea Room Ltd | Hospitality | 2025 |
| Thornham Property Company Limited | Construction | 2022 |
| Thornhill Square Ltd | Financial services | 2017 |
| Thornhill Support Services Limited | Administrative & support | 2025 |
| Thorokleen Holdings Limited | Financial services | 2003 |
| Thorokleen Trading Limited | Administrative & support | 2010 |
| Thorokleen Trustees Limited | Other services | 2019 |
| Thorpe Cleaning Ltd | Administrative & support | 2021 |
| Thorpe Cleaning Services Limited | Administrative & support | 2015 |
| Thorpe Clinic Ltd | Health & social care | 2024 |
| Thorpe Meadows Properties Ltd | Real estate | 2022 |
| Thorpe Meadows Residents Company Limited | Households | 1988 |
| Thorpe Park (Peterborough) Management Company Limited | Households | 2003 |
| Thorpe Park Properties (Cambs) Ltd | Construction | 2025 |
| Thorpe Park Properties Holdings Ltd | Financial services | 2025 |