| Third Time Lucky (South Yorkshire) Ltd | Hospitality | 2024 |
| Thirty Three Property Assets Ltd | Construction | 2022 |
| Thirtyone Fundraising Limited | Administrative & support | 2012 |
| This GUY at Night Limited | Arts & recreation | 2014 |
| Thisegg Ltd | Arts & recreation | 2019 |
| Thissaway Limited | Professional & scientific | 2001 |
| Thomas ALI Ltd | Education | 2020 |
| Thomas Archer Homes Limited | Construction | 2016 |
| Thomas Business Limited | Real estate | 2023 |
| Thomas Garland Limited | Professional & scientific | 2016 |
| Thomas Goodliffe Surveying Limited | Professional & scientific | 2014 |
| Thomas James Properties U.K. Limited | Households | 2019 |
| Thomas Minns Property Ltd | Real estate | 2020 |
| Thomas Peter Nicholson Limited | Professional & scientific | 2016 |
| Thomas Swabey Consultancy Ltd | Professional & scientific | 2022 |
| Thomas Transport Limited | Wholesale & retail | 1935 |
| Thomerson Interiors Group Ltd | Other services | 2019 |
| Thompson and Thompson Lettings Limited | Real estate | 2018 |
| Thompson and Thompson Properties Ltd | Real estate | 2016 |
| Thompson Building & Maintenance Ltd | Hospitality | 2023 |
| Thompson Contracting Limited | Construction | 2014 |
| Thompson Packaging Limited | Manufacturing | 1998 |
| Thompson Property Refurbishment Limited | Construction | 2024 |
| Thompson's Property & Letting Limited | Real estate | 2023 |
| Thompsons Lettings Norfolk Ltd | Hospitality | 2023 |
| Thomson & Joseph Limited | Wholesale & retail | 1987 |
| Thomson Land Holdings LLP | | 2021 |
| Thomson Sawmills Holdings Limited | Agriculture & fishing | 2012 |
| Thomson Sawmills Limited | Manufacturing | 1996 |
| Thonock & Somerby Estates (NO.2) Limited | Real estate | 2024 |
| Thonock & Somerby Estates Limited | Real estate | 2024 |
| Thor Ltd | Other services | 2023 |
| Thor Management Limited | Financial services | 2023 |
| Thor Toolservices Ltd | Professional & scientific | 2012 |
| Thornber Woolf Ltd | Hospitality | 2022 |
| Thornberry Grove (Spooner ROW) Management Company Limited | Households | 2022 |
| Thornfleet Holdings Ltd | Real estate | 2023 |
| Thornham Advisory Limited | Administrative & support | 2016 |
| Thornhill Green Redgrave Management Company Limited | Households | 2022 |
| Thornley Property Holdings Ltd | Real estate | 2021 |
| Thornton & LEE Ltd | Health & social care | 2020 |
| Thornwood Construction Ltd | Construction | 2015 |
| Thorpe Blenders Barbers Ltd | Other services | 2024 |
| Thorpe Contracting Ltd | Wholesale & retail | 2023 |
| Thorpe END Garage Limited | Wholesale & retail | 2006 |
| Thorpe Ferry Cafe Ltd | Hospitality | 2025 |
| Thorpe Ferry Limited | Transport & logistics | 2014 |
| Thorpe Flooring Services Ltd | Construction | 2014 |
| Thorpe Hamlet Lodge Management Ltd | Households | 2010 |
| Thorpe Heights Management Company Limited | Real estate | 2004 |
| Thorpe Homes Developments Limited | Real estate | 2017 |
| Thorpe Homes Holdings Limited | Financial services | 2017 |
| Thorpe Oak Investments Ltd | Other services | 2016 |
| Thorpe Park Management Company Limited | Real estate | 1987 |
| Thorpe Properties Limited | Administrative & support | 1954 |
| Thorpe ST Andrew Care Village Limited | Health & social care | 2018 |
| Thorpe ST Andrew Hand Car Wash Ltd | Wholesale & retail | 2016 |
| Thorpe Taxis Ltd | Transport & logistics | 2025 |
| THOUGHT4FOOD Consultancy Limited | Other services | 2013 |
| THR1V Ltd | Wholesale & retail | 2025 |
| Threads Streetwear Ltd | Wholesale & retail | 2025 |
| Threadwell Wholesale Ltd | Wholesale & retail | 2025 |
| Three Acres Management Limited | Households | 2022 |
| Three Circle Line Cruisers Limited | | 1974 |
| Three Crowns ENT Ltd | Health & social care | 2024 |
| Three Crowns Lettings Limited | Real estate | 2016 |
| Three Kings Limited | Construction | 2013 |
| Three Peggs Limited | Extraterritorial | 2021 |
| Three Score Open Space Management Limited | Households | 2018 |
| Three Tuns Court Management Company Limited | Real estate | 1986 |
| Thresh Developments Ltd | Construction | 2024 |
| Thrift Farmstead Management Company Limited | Real estate | 2025 |
| Thrifty Mobility Ltd. | Wholesale & retail | 2021 |
| Thrive Fintech Ltd | Information & communication | 2024 |
| Thrive Lane Studio Ltd | Information & communication | 2025 |
| Thrive Residential Limited | Real estate | 2017 |
| Thrive Supplements Ltd | Wholesale & retail | 2026 |
| Thsm Cambridge Limited | Real estate | 2025 |
| Thunder Films Ltd | Administrative & support | 2019 |
| Thurlby & ST Hughs (Airmen's Houses) Management Company Limited | Professional & scientific | 2004 |
| Thurley Homes Ltd | Construction | 2017 |
| Thurlow Consulting Ltd | Information & communication | 2014 |
| Thurlton Community Store C.I.C. | Wholesale & retail | 2016 |
| Thurn Group Ltd. | Professional & scientific | 2011 |
| Thurne Bungalows Management Company Limited | Households | 1985 |
| Thurne-Middleby Ltd | Manufacturing | 2015 |
| Thurnefield Limited | Hospitality | 2023 |
| Thurstan Wright Consulting Ltd | Professional & scientific | 2025 |
| Thurton Auto Centre Ltd | Wholesale & retail | 2024 |
| Thus Consulting Ltd | Professional & scientific | 2020 |
| Thwaite Hill Farm Residents Limited | Households | 2014 |
| Thyme TU Ltd | Manufacturing | 2021 |
| TI Jones & Sons Ltd | Real estate | 2014 |
| TI88 Limited | Financial services | 2020 |
| Tiande Shop Ltd | Wholesale & retail | 2020 |
| Tibbs Fitness Ltd | Other services | 2022 |
| Tibby's Triangle Management Company Limited | Households | 2008 |
| Ticket Realm Suppliers Ltd | Wholesale & retail | 2025 |
| Tickety BOO Toys Ltd | Administrative & support | 2010 |
| Ticktack Limited | Professional & scientific | 2016 |