| THE Means Ltd | Professional & scientific | 2013 |
| THE Meltdown Station Ltd | Hospitality | 2026 |
| THE Mobile Film School Ltd | Information & communication | 2019 |
| THE Mumbles Consultancy LLP | | 2023 |
| THE New Thomas Arms Group Ltd | Hospitality | 2024 |
| THE Old Dragon Ltd | Wholesale & retail | 2024 |
| THE Old Wagon Wheel Ltd | Hospitality | 2019 |
| THE Parts Shelf Ltd | Wholesale & retail | 2023 |
| THE Payroll and Pensions Team Limited | Professional & scientific | 2022 |
| THE Phil Bennett Ltd | Hospitality | 2023 |
| THE Pitch (Felinfoel) Limited | Hospitality | 2024 |
| THE Planning GUY (RG) Ltd | Professional & scientific | 2021 |
| THE Property Lane Limited | Real estate | 2019 |
| THE Ranch Llanelli Limited | Hospitality | 2026 |
| THE Second 45 Ltd. | Wholesale & retail | 2022 |
| THE Secret Planthouse Limited | Agriculture & fishing | 2025 |
| THE Sensory Haven Limited | Health & social care | 2026 |
| THE Stradey Arms Limited | Hospitality | 2020 |
| THE Stubborn Duckling Ltd | Hospitality | 2020 |
| THE Studio Llanelli Ltd | Real estate | 2021 |
| THE Sultan Llanelli Ltd | Hospitality | 2019 |
| THE Supercar Sanctuary Ltd | Transport & logistics | 2025 |
| THE Taste of Bharat Limited | Hospitality | 2024 |
| THE Television Corporation Limited | Information & communication | 1974 |
| THE TIN Shack Company Ltd | Wholesale & retail | 2025 |
| THE Tipsy Turk Ltd | Hospitality | 2026 |
| THE VRC Yoganathan LLP | | 2009 |
| THE World of Play 2007 Limited | Arts & recreation | 2007 |
| THE Yoga Therapy Hub CIC | Education | 2026 |
| Thegreenshouse Ltd | Real estate | 2019 |
| Thesunicollection Ltd | Wholesale & retail | 2026 |
| Thomas & Thomas Plant and Tool Hire Ltd | Administrative & support | 2010 |
| Thomas (Llanelli) Lettings Ltd | Real estate | 2013 |
| Thomas Barbers Ltd | Other services | 2024 |
| Thomas Brett Johns Limited | Arts & recreation | 2017 |
| Thomas Capital Group Limited | Construction | 2025 |
| Thomas Evans & Co. Limited | Construction | 2018 |
| Thomas Glass Limited | Construction | 2011 |
| Thomas Homes West Ltd | Construction | 2010 |
| Thomfield Engineering Limited | Professional & scientific | 2015 |
| Thornes Lettings Limited | Households | 2021 |
| Thornes Limited | Real estate | 2008 |
| Thornes Llanelli Ltd | Wholesale & retail | 2020 |
| Three Pillars Properties Limited | Real estate | 2024 |
| Threshold DAS Limited | Health & social care | 2007 |
| Thrice Investments Ltd | Financial services | 2023 |
| Thryve Consulting Group Ltd | Professional & scientific | 2025 |
| THW Property Group Ltd | Real estate | 2024 |
| Thyssen Way Pipeline Services Limited | Professional & scientific | 2015 |
| Tiger Textiles Limited | Wholesale & retail | 2019 |
| Tigerson Ltd | Construction | 2005 |
| Timbex Ltd | Manufacturing | 2019 |
| Tina Lloyd Financial Services Limited | Financial services | 2015 |
| Tinopolis Facilities Ltd | Information & communication | 1991 |
| Tinopolis Group Limited | Financial services | 2020 |
| Tinopolis Interactive Limited | Information & communication | 1997 |
| Tinopolis Limited | Information & communication | 1999 |
| Tiny Tots Town Ltd | Hospitality | 2023 |
| Tiny Tots Treats Limited | Hospitality | 2025 |
| Tiptopjnr Properties Ltd | Households | 2024 |
| Tiqi Limited | Information & communication | 2020 |
| TJ Elite Resin Ltd | Administrative & support | 2023 |
| Tjlife Ltd | Professional & scientific | 2020 |
| TK Orthopaedics Ltd | Health & social care | 2022 |
| Tkps Property Ltd | Real estate | 2024 |
| TLH Online Limited | Professional & scientific | 2006 |
| Tlporter Electrical Contractor Ltd | Construction | 2018 |
| TM Networks Ltd | Information & communication | 2017 |
| TM Removals & Waste Ltd | Transport & logistics | 2026 |
| Tmcp Limited | Real estate | 2023 |
| TMR Technologies Ltd | Information & communication | 2025 |
| Tobi Davies Limited | Professional & scientific | 2013 |
| Together Strategy Ltd | Professional & scientific | 2007 |
| Toplis Project Services Ltd | Extraterritorial | 2014 |
| Toppers Wales Ltd | Hospitality | 2008 |
| Torpedo South Limited | Construction | 2014 |
| Toshack Ltd | Hospitality | 2025 |
| Total Buggy Services Ltd | Administrative & support | 2021 |
| Total Quantity Surveying Ltd | Administrative & support | 2016 |
| Totally Polished Ltd | Other services | 2012 |
| Totc Ltd | Education | 2023 |
| Touch of Beauty Ltd | Other services | 2022 |
| Tower Architectural Products Ltd | Manufacturing | 2019 |
| Towy Electrical Company Limited | Construction | 1980 |
| Towy Valley Heating Ltd | Construction | 2016 |
| TPW Consulting Ltd | Information & communication | 2026 |
| Tradeforce Solutions Ltd | Administrative & support | 2025 |
| Trademx Limited | Wholesale & retail | 2019 |
| Traed Iach Podiatry Ltd | Health & social care | 2022 |
| Transport Consultancy Wales Ltd | Transport & logistics | 2018 |
| Tree on the Hill Films Limited | Information & communication | 2022 |
| Tree Tech ARB & Forestry Services Ltd | Agriculture & fishing | 2021 |
| Treharne Automotive Engineering Limited | Manufacturing | 2008 |
| Treharne Holdings Limited | Manufacturing | 2016 |
| Treseder Productions Limited | Arts & recreation | 2017 |
| Tricopper Property Limited | Real estate | 2026 |
| Trident Precision Engineering Limited | Manufacturing | 2012 |
| Trident Threads Ltd | Manufacturing | 2024 |
| Trimology (Llanelli) Limited | Other services | 2024 |
| Trojan Team Wear Group Ltd | Wholesale & retail | 2020 |