| Tonic Solutions Ltd | Information & communication | 2013 |
| Tonna Ground Rents Limited | Real estate | 2021 |
| Tonna Luxury Coaches Limited | Transport & logistics | 1964 |
| Tonner Johns Ratti Limited | Professional & scientific | 2006 |
| Tontorontosent Ltd | Manufacturing | 2021 |
| Tony Garthwaite Limited | Professional & scientific | 2009 |
| Tony Unsworth Limited | Other services | 2012 |
| Tony's Tenders Ltd | Hospitality | 2025 |
| Tonys Colourworx Ltd | Wholesale & retail | 2025 |
| Tool & Cutter Holdings Limited | Professional & scientific | 2000 |
| Tool Archive Limited | Information & communication | 2023 |
| Tools N Tools UK Ltd | Wholesale & retail | 2014 |
| Tootonic Ltd | Wholesale & retail | 2009 |
| Top Assist Ltd | Administrative & support | 2018 |
| Top Barber (Peniel Green) Limited | Other services | 2023 |
| Top Field Media Ltd | Information & communication | 2022 |
| Top Pops Properties Ltd | Real estate | 2025 |
| Top Pops Wholesaler of Soft Drinks Limited | Wholesale & retail | 2005 |
| Top Priority Solutions Limited | Administrative & support | 2022 |
| Top Vouchers Ltd | Information & communication | 2026 |
| Topass Ltd | Financial services | 2025 |
| Topaz Financial Solutions LLP | | 2012 |
| Topcat Homes Limited | Real estate | 2026 |
| Topcoat Industrial Supplies Ltd | Manufacturing | 2021 |
| Topgrade Homes Ltd | Construction | 2015 |
| Topgrade Property Management Limited | Real estate | 2014 |
| Topolis Pizza and Kebab House Ltd | Hospitality | 2019 |
| TOPTOYS2U Limited | Wholesale & retail | 2007 |
| TOR House Management Company Limited | Households | 1997 |
| Torchwood Properties Limited | Construction | 1991 |
| Torii Gate Bonsai Limited | Administrative & support | 2022 |
| Torque Automotive Engineering Limited | Wholesale & retail | 2013 |
| Torri TIR Ltd | Professional & scientific | 2009 |
| Tosca Ltd | Real estate | 2020 |
| Total Bathroom Solutions Ltd | Construction | 2024 |
| Total Body Fitness & DJ Boxing Limited | Other services | 2026 |
| Total Build & Property Maintenance Ltd | Construction | 2025 |
| Total Building Control Group Ltd | Financial services | 2017 |
| Total Building Control Ltd | Professional & scientific | 2004 |
| Total Care (Wales) Ltd | Construction | 2014 |
| Total Cleaning Solutions Ltd | Administrative & support | 2006 |
| Total Cleaning Specialists Ltd | Administrative & support | 2025 |
| Total Energy Systems Ltd | Construction | 2018 |
| Total Group Building Services Ltd | Construction | 2017 |
| Total Marine Services Ltd | Manufacturing | 2025 |
| Total Perspective Media Limited | Information & communication | 2022 |
| Total Site Maintenance Limited | Administrative & support | 2001 |
| Total Technology (Engineering) Limited | Administrative & support | 1975 |
| Total Technology Design Partnership Limited | Construction | 2000 |
| Toucan Press Ltd | Information & communication | 2025 |
| Toucan Travel Cymru Limited | Real estate | 2004 |
| Tough Runner UK Ltd | Arts & recreation | 2017 |
| TOUR3D360 Limited | Professional & scientific | 2018 |
| Tourism Swansea Bay Limited | Administrative & support | 2005 |
| Tourist Golf Limited | Wholesale & retail | 2023 |
| Tours and Beds Limited | Administrative & support | 2020 |
| Town & Country Property Auctions (South Wales) Ltd | Real estate | 2022 |
| Town Shop Ltd | Wholesale & retail | 2026 |
| Townhill Property Limited | Real estate | 2026 |
| Townhill Spice Ltd | Hospitality | 2020 |
| Townhill Tandoori Ltd | Hospitality | 2018 |
| Towy Ltd | Hospitality | 2022 |
| Towy Properties Limited | Real estate | 2022 |
| Toxic Lace Ltd | Wholesale & retail | 2021 |
| Toyebarn Ltd | Wholesale & retail | 2025 |
| Toys and Masks Limited | Wholesale & retail | 2015 |
| Toys UN Limited | Extraterritorial | 2023 |
| TP Enterprises (Swansea) Ltd | Hospitality | 2019 |
| TP Rhythm SPV Ltd | Construction | 2018 |
| TP Vinyl Records Limited | Wholesale & retail | 2025 |
| TPA Project Consultancy Limited | Professional & scientific | 2012 |
| Tpal Properties Ltd | Real estate | 2026 |
| TPB Management & Catering Services Ltd | Hospitality | 2017 |
| TPJ ERP Consulting Ltd | Information & communication | 2025 |
| TPM Property Services Ltd | Construction | 2017 |
| TPN Electrical Engineers Limited | Construction | 2004 |
| Tpow Ltd | Wholesale & retail | 2024 |
| TPR Property Maintenance Ltd | Construction | 2023 |
| Tpts Fitness Ltd | Arts & recreation | 2015 |
| TR Fleet Limited | Professional & scientific | 2007 |
| TR Scaffolding Ltd | Construction | 2024 |
| TRA Venturing Limited | Professional & scientific | 2017 |
| Tracy David Ltd | Wholesale & retail | 2012 |
| Tradalgo Ltd. | Wholesale & retail | 2017 |
| Trade Cars Direct (Swansea) Limited | Wholesale & retail | 2006 |
| Trade CARS4U Limited | Wholesale & retail | 2019 |
| Trade Cost Windows Limited | Construction | 2012 |
| Trade Directory Limited | Information & communication | 2023 |
| Trade Exhibitions Ltd | Professional & scientific | 2025 |
| Trade Management Solutions Ltd | Administrative & support | 2026 |
| Trade Marc Ltd | Real estate | 2017 |
| Trade Souls Ltd | Wholesale & retail | 2025 |
| Trade Suite HQ Ltd | Professional & scientific | 2025 |
| Tradeconsult (UK) Limited | Wholesale & retail | 2014 |
| Trader Transport Ltd | Transport & logistics | 2021 |
| Traders' Reconstruction(Swansea)Limited | Administrative & support | 1955 |
| Tradie Events Ltd | Arts & recreation | 2025 |
| Trading UN Limited | Extraterritorial | 2023 |
| Trading W F Ltd | Transport & logistics | 2024 |
| Traethlin Ltd. | Information & communication | 2026 |