| Threadandverse Ltd | Wholesale & retail | 2026 |
| Threadline Studios Ltd | Information & communication | 2025 |
| Threadntrend Ltd | Wholesale & retail | 2026 |
| Threads Direct Limited | Wholesale & retail | 2011 |
| Threadswelove Limited | Wholesale & retail | 2023 |
| Threatcore Ltd | Professional & scientific | 2026 |
| Three Arrows Furniture & Floorings Ltd | Wholesale & retail | 2025 |
| Three Arrows Leicester Ltd | Wholesale & retail | 2024 |
| Three Arrows UK Ltd | Wholesale & retail | 2026 |
| Three Brothers Investments Limited | Financial services | 2023 |
| Three Counties Brickwork Ltd | Construction | 2021 |
| Three D Landscapes Ltd | Administrative & support | 2002 |
| Three Financial Planning Limited | Professional & scientific | 2025 |
| Three Four Nine Ltd | Manufacturing | 2018 |
| Three Future Technologies Limited | Information & communication | 2025 |
| Three G Metal Fabrications Ltd | Manufacturing | 1999 |
| Three Leaf Fitness Ltd | Arts & recreation | 2019 |
| Three Light Star Limited | Professional & scientific | 2024 |
| Three Oxford Road (Teddington) Limited | Extraterritorial | 1987 |
| Three Social Limited | Professional & scientific | 2024 |
| Three Thinking Ltd | Professional & scientific | 2012 |
| Three Veers Group Limited | Real estate | 2022 |
| Threefold Holdings Limited | Financial services | 2026 |
| Threehorseslogistic Ltd | Transport & logistics | 2026 |
| Threejuvenation Limited | Health & social care | 2025 |
| Threesixty HOLDCO3 Limited | Financial services | 2020 |
| Threeways Investments Ltd | Real estate | 2014 |
| Thringstone Transport Ltd | Transport & logistics | 2014 |
| Thrive Kidz Intensives Ltd | Health & social care | 2025 |
| Thrive Massage Limited | Other services | 2025 |
| Thrive Nest Living Ltd | Administrative & support | 2025 |
| THRIVE360 Solutions Ltd | Professional & scientific | 2025 |
| Thrivepm Consultancy Ltd | Real estate | 2025 |
| Throckenholt Ltd | Transport & logistics | 2015 |
| Throgmorton Investment Management Ltd | Financial services | 2009 |
| Throux Developments Ltd | Construction | 2026 |
| Thrower IT Ltd | Information & communication | 2019 |
| Thrussington Garage Ltd | Wholesale & retail | 2014 |
| Thrussington Management Services Ltd | Administrative & support | 2019 |
| Thrussingtons Limited | Wholesale & retail | 2011 |
| Thss Limited | Real estate | 2013 |
| Thuan MEN Limited | Other services | 2023 |
| Thumma Services Ltd | Information & communication | 2025 |
| Thunder Domain Ltd | Administrative & support | 2010 |
| Thundridge Pioneer Ltd | Administrative & support | 2015 |
| Thurat Limited | Extraterritorial | 2023 |
| Thurcaston Properties Limited | Real estate | 2007 |
| Thureiya Limited | Health & social care | 2022 |
| Thurlaston Catering Ltd | Hospitality | 2024 |
| Thurmaston African Grocery Shop Limited | Hospitality | 2025 |
| Thurmaston Dental Practice Ltd | Health & social care | 2013 |
| Thurmaston Food and Wine Limited | Wholesale & retail | 2023 |
| Thurmaston Pharmacy Limited | Wholesale & retail | 2009 |
| Thurmaston Properties Ltd | Real estate | 2022 |
| Thurmaston Rental Centre Ltd | Real estate | 2018 |
| Thurmaston Rewinds Ltd | Manufacturing | 2012 |
| Thurmaston Times Ltd | Information & communication | 2020 |
| Thurnby Chippy Limited | Hospitality | 2010 |
| Thurnby Electrical Services Limited | Construction | 2014 |
| Thurnby Eyecare Ltd | Health & social care | 2016 |
| Thurnby GAS Services Limited | Construction | 2021 |
| Thurnby Lodge Car Valeting Ltd | Administrative & support | 2025 |
| Thurnby Properties Ltd | Real estate | 2025 |
| Thurnview Holdings Ltd | Health & social care | 2022 |
| Thurnview Properties Ltd | Real estate | 2025 |
| Thurton Realty Ltd | Real estate | 2025 |
| Thuthukatamandayi Evolution Care Limited | Extraterritorial | 2015 |
| Thyme Abodes Ltd | Households | 2024 |
| TIA Corporation Ltd | Hospitality | 2024 |
| TIA News Limited | Wholesale & retail | 2006 |
| TIA Properties Ltd | Real estate | 2019 |
| Tiara Companies Ltd | Other services | 2023 |
| Tiara Developments Ltd | Real estate | 2022 |
| Tiara Packaging Ltd | Wholesale & retail | 2023 |
| Tibberton Haulage Ltd | Transport & logistics | 2014 |
| Tiberio Enterprise Ltd | Professional & scientific | 2018 |
| Tibi Omnia Ltd | Wholesale & retail | 2026 |
| Tickhill Superstores Limited | Wholesale & retail | 2021 |
| Tidal Robes Ltd | Wholesale & retail | 2024 |
| Tidebrook Unsurpassed Ltd | Administrative & support | 2015 |
| Tidy Plastering Limited | Construction | 2006 |
| Tidy Town Cleaners Ltd | Administrative & support | 2025 |
| Tie-Tight Laces Limited | Extraterritorial | 2021 |
| Tier 2 Jobs Ltd | Administrative & support | 2023 |
| Tiernan Automation Holdings Limited | Financial services | 2024 |
| Tierone Recruiting Ltd | Administrative & support | 2026 |
| Tierra Tapas Ltd | Real estate | 2025 |
| Tifaura Limited | Wholesale & retail | 2025 |
| Tiffany Bar Limited | Wholesale & retail | 2015 |
| Tiffer Holdings Limited | Professional & scientific | 2005 |
| Tiffin Wala Leicester Ltd | Hospitality | 2024 |
| Tiger Cleaning Limited | Administrative & support | 2019 |
| Tiger Home Property Investments Limited | Real estate | 2018 |
| Tiger Lily Tattoo Studio Ltd | Other services | 2025 |
| Tiger Oriental UK Ltd | Hospitality | 2019 |
| Tiger-Ltd Limited | Wholesale & retail | 2019 |
| Tigers Events Limited | Arts & recreation | 2003 |
| Tigers Roll Limited | Hospitality | 2013 |
| Tigo Ltd | Transport & logistics | 2019 |
| Tigola Technologies Ltd | Transport & logistics | 2017 |