| TLC Engineering Solutions Ltd | Manufacturing | 2007 |
| TO ME to YOU - Storage Limited | Real estate | 2022 |
| TOG Farm Ltd | Financial services | 2020 |
| TOL Caerphilly Community Interest Company | Hospitality | 2025 |
| Tool Raptors Ltd | Manufacturing | 2015 |
| Toponym Design Ltd | Professional & scientific | 2024 |
| Torq Cymru Automotive Ltd | Wholesale & retail | 2026 |
| Total Carglass Solutions Limited | Wholesale & retail | 2019 |
| Total Cooling Services Ltd | Construction | 2015 |
| Total Ground Maintenance Limited | Administrative & support | 2009 |
| Total Protective Solutions 360 Limited | Construction | 2008 |
| Total Sporting Solution Ltd | Wholesale & retail | 2007 |
| Totti Tech Limited | Information & communication | 2025 |
| Tower Fire Limited | Administrative & support | 2005 |
| Tower Systems (South Wales) Limited | Professional & scientific | 2010 |
| Toybox Project Community Interest Company | Wholesale & retail | 2020 |
| TPS 360 Holdings Limited | Real estate | 2023 |
| Trace Bookkeeping and Accounting Ltd | Professional & scientific | 2022 |
| Tradmalt (Plastics) Limited | Manufacturing | 1989 |
| Trainerlab Ltd | Extraterritorial | 2008 |
| Tralex 365 Limited | Construction | 2022 |
| Trane Investments Limited | Real estate | 2021 |
| Transcend Packaging Limited | Manufacturing | 2017 |
| Travel Global Limited | Information & communication | 2019 |
| Tredegar Farmers Hunt Limited | Arts & recreation | 2019 |
| Tree Check Arboriculture Ltd | Professional & scientific | 2021 |
| Tree Top Films Limited | Information & communication | 2014 |
| Tree Top Studios Ltd | Information & communication | 2025 |
| Tree Transport and Logistics Ltd | Transport & logistics | 2021 |
| Treefish Ltd | Information & communication | 2025 |
| Tremethic Timber Frame Company Limited | Manufacturing | 1989 |
| Trendy Shoes Ltd | Wholesale & retail | 2022 |
| Trethomas Mini Market Ltd | Wholesale & retail | 2026 |
| TRIBE517 Ltd | Other services | 2016 |
| Trinity Films Limited | Administrative & support | 2019 |
| TRO DA Ltd | Health & social care | 2018 |
| Trojan Carpentry Limited | Construction | 2018 |
| True Future Limited | Wholesale & retail | 2022 |
| True North Roofing and Cladding Ltd | Construction | 2024 |
| Trueblue Prod Limited | Information & communication | 2026 |
| Trulife Property Management Ltd | Real estate | 2024 |
| Truscon Limited | Construction | 2024 |
| Trysor Systems Engineering Ltd | Information & communication | 2022 |
| TSF Dream Limited | Transport & logistics | 2018 |
| Tubesaccess Ltd | Extraterritorial | 2020 |
| TUN Tech Electrical Limited | Construction | 2021 |
| Turkish Hair Design Ltd | Other services | 2025 |
| Twelvetechnology Ltd | Information & communication | 2019 |
| Twirl and Treat Ltd | Hospitality | 2025 |
| Twisted Pair Technologies Limited | Construction | 2010 |
| TWR Web Design Limited | Information & communication | 2021 |
| Twyn Developments Ltd | Construction | 2024 |
| TY Bryn & Village Medical Services Limited | Health & social care | 2019 |
| TY Capel Apartments (Management Company) Limited | Real estate | 2017 |
| TY Catref Ltd | Real estate | 2024 |
| TY Crwn Developments Ltd | Real estate | 2023 |
| Tyfu Consulting Ltd | Professional & scientific | 2025 |
| Tyre Glider Limited | Wholesale & retail | 2021 |
| Ty’R Felin Holdings Limited | Professional & scientific | 2017 |
| UAK Tutors Limited | Education | 2021 |
| UK Capital Holdings Ltd | Financial services | 2021 |
| UK First AID Supplies Limited | Professional & scientific | 2025 |
| UK JC Investments Ltd | Real estate | 2026 |
| UK Mortgage and Protection Ltd | Financial services | 2011 |
| UK Rise Development Co Limited | Professional & scientific | 2026 |
| UK Wills & Estates Limited | Other services | 2011 |
| Ultimate Arcade Cabinets Ltd | Manufacturing | 2015 |
| Ultraponix Global CIC | Agriculture & fishing | 2016 |
| Ultraponix International Ltd | Wholesale & retail | 2017 |
| Ultraponix Ltd | Professional & scientific | 2013 |
| Underham Holdings Limited | Households | 2022 |
| Unearth Possibility CIC | Education | 2025 |
| Unique Gift Workshop Ltd. | Arts & recreation | 2019 |
| Unique Leisure Property Holdings Limited | Real estate | 2009 |
| Unique Polystyrene Ltd | Manufacturing | 2020 |
| Universal Resource Trading Limited | Wholesale & retail | 2015 |
| Unleashed Bars Limited | Hospitality | 2025 |
| UP Market Family Butchers Surf & Turf Ltd | Wholesale & retail | 2024 |
| UP Market Family Seafood Online Ltd | Wholesale & retail | 2024 |
| UP to 11 Ltd | Wholesale & retail | 2020 |
| Upmarket Family Butchers Limited | Wholesale & retail | 2023 |
| Urban Elegance Limited | Manufacturing | 2017 |
| Urban Elegance Property Ltd | Real estate | 2026 |
| Urban Property Executive Ltd | Real estate | 2025 |
| Urban Property Regeneration Limited | Construction | 2025 |
| UTS Bodyshops Limited | Manufacturing | 2014 |
| V Hair Academy Ltd | Other services | 2020 |
| Valedown Limited | Health & social care | 2005 |
| Validviewnetwork Limited | Agriculture & fishing | 2022 |
| Valley Developments and Services Limited | Real estate | 1999 |
| Value Vets Ltd | Professional & scientific | 2019 |
| VB Aero Engine Consultancy Services Ltd | Other services | 2021 |
| Veil & Bloom Ltd | Wholesale & retail | 2025 |
| Venture OUT Training Ltd | Education | 2019 |
| Vetro Health Limited | Administrative & support | 2016 |
| Vetro Recruitment Limited | Administrative & support | 2015 |
| Vibe PR and Marketing Limited | Wholesale & retail | 2003 |
| Vibrant Blinds and Shutters Ltd | Construction | 2022 |
| Vidah Retreats Ltd | Other services | 2021 |
| Vision and Vibes Entertainment Limited | Arts & recreation | 2026 |