| T D Developments Ltd | Construction | 2002 |
| T&B Enterprises (Tywyn) Ltd | Hospitality | 2021 |
| T&R Lettings Ltd | Real estate | 2025 |
| T.W.I.G. Woodland Management Ltd. | Agriculture & fishing | 2016 |
| T1GER Fuel Limited | Wholesale & retail | 2023 |
| Tafarn Y Gader Ltd | Hospitality | 2014 |
| TAI Dyffryn CYF. | Real estate | 2013 |
| Tair Chwaer CYF | Real estate | 2022 |
| Tairllyn Developments Limited | Real estate | 2004 |
| Tammy Aloe Ltd | Other services | 2023 |
| Tango Tours Ltd | Administrative & support | 2008 |
| Tanybwlch Farm Limited | Agriculture & fishing | 2025 |
| Tanyrallt Estates Limited | Other services | 2003 |
| Taran Timing Systems Ltd | Manufacturing | 2026 |
| Tatenda 06 Limited | Health & social care | 2021 |
| Tatws Limited | Hospitality | 2017 |
| TE Facilities Ltd | Real estate | 2021 |
| Teaselfinch Ltd | Professional & scientific | 2022 |
| Techion (UK) Ltd | Professional & scientific | 2014 |
| Teledu Sali Mali CYF | Information & communication | 2026 |
| Terra & Tide Collective Ltd | Hospitality | 2026 |
| THE Adventure of Wellbeing Ltd | Education | 2023 |
| THE Big Science Project Ltd | Education | 2025 |
| THE Chip Box Penparcau Ltd | Hospitality | 2026 |
| THE ETD Letting Company Ltd | Real estate | 2018 |
| THE Foot Health Clinic (Ceredigion) Ltd | Health & social care | 2026 |
| THE Gym Aber Ltd | Arts & recreation | 2025 |
| THE Harper Norfolk Ltd | Hospitality | 2026 |
| THE Insights Shed Ltd | Professional & scientific | 2009 |
| THE Light of Asia Ltd | Hospitality | 2014 |
| THE Mecca (Tea & Coffee Merchants) Limited | Wholesale & retail | 2003 |
| THE NFT Project Ltd. | Information & communication | 2021 |
| THE Pier Aberystwyth Ltd | Hospitality | 2024 |
| THE Prickly Pear Patisserie Ltd | Wholesale & retail | 2025 |
| THE Suzie Label Limited | Wholesale & retail | 2025 |
| THE White Swan Inn Ltd | Hospitality | 2026 |
| Thewatchhouse Ltd | Hospitality | 2025 |
| Thin Place Productions Ltd | Information & communication | 2015 |
| Thomas Parry Clocks Ltd | Wholesale & retail | 2019 |
| Threat Works Ltd | Professional & scientific | 2018 |
| Three Eyed Circus Ltd | Education | 2025 |
| Three Glovers Ltd | Agriculture & fishing | 2024 |
| Threesix Holdings Limited | Professional & scientific | 2023 |
| Threesix Investments Limited | Real estate | 2022 |
| TIM Dean Plumbing and Heating Solutions Limited | Construction | 2020 |
| Timber Design Wales Ltd | Construction | 2023 |
| TIR Coed | Agriculture & fishing | 2000 |
| Tirddaliadau Rheidol Cyfyngedig | Real estate | 1992 |
| Tirlun Planning Ltd | Professional & scientific | 2026 |
| Tjlj Properties Ltd | Real estate | 2026 |
| TME Electrical Contracting Ltd | Construction | 2002 |
| TME Electrical Ltd | Construction | 2018 |
| TME Limited | Wholesale & retail | 2019 |
| TMW Carpentry & Construction Ltd | Manufacturing | 2026 |
| TNR Trading Ltd | Wholesale & retail | 2017 |
| Tognell Limited | Households | 2019 |
| TOM Jewell Carpentry & Building Ltd | Construction | 2023 |
| TOM Rooth Designs Ltd | Manufacturing | 2018 |
| TOM Rooth Fine Art Ltd | Wholesale & retail | 2017 |
| Tomlyn Limited | Extraterritorial | 2016 |
| Tonnau CYF | Information & communication | 2020 |
| Top Bricks Limited | Real estate | 2020 |
| Top Notch Loos Ltd | Administrative & support | 2022 |
| Top Notch Property Management Ltd | Real estate | 2025 |
| Torino Enterprises Limited | Transport & logistics | 1999 |
| Torrent Walk Hotel Ltd | Hospitality | 2014 |
| Town Cabs Ltd | Transport & logistics | 2026 |
| Townhouse NO.1 Limited | Hospitality | 2020 |
| Trailblazer Tournaments Limited | Education | 2024 |
| Trawsgoed Estate Roads Limited | Real estate | 1999 |
| Trewen Consultancy Limited | Professional & scientific | 2014 |
| Trydan AJ Electrical Ltd | Construction | 2025 |
| Trydan Will Davey Electrical Ltd | Construction | 2023 |
| Trydon Limited | Real estate | 2020 |
| TS Regulatory Compliance & Advice Services Ltd | Administrative & support | 2023 |
| Tudalen Ltd | Information & communication | 2013 |
| Turkish Barber 15 Ltd | Other services | 2026 |
| Turkish Barberr Ltd | Other services | 2024 |
| Turtley Techy Ltd | Information & communication | 2025 |
| Two Hoots Catering Limited | Hospitality | 2025 |
| Twodays Property Co. Ltd | Construction | 2022 |
| TY Ceredig Management Limited | Real estate | 2010 |
| TY Padarn Management Limited | Real estate | 2013 |
| TY Rhos Property Management Limited | Real estate | 2009 |
| Tynrhos (UK) Limited | Health & social care | 2011 |
| U.A.W Limited | Real estate | 2014 |
| Uhbc Limited | Other services | 2003 |
| UK Engraving Ltd | Manufacturing | 2019 |
| Ultimate Alloys Refurbishment Ltd | Wholesale & retail | 2023 |
| Ultracomida Limited | Wholesale & retail | 2008 |
| Ultracomida Trading Co. Limited | Wholesale & retail | 2010 |
| Unigryw Cyfyngedig | Information & communication | 2002 |
| Unstable UK Limited | Arts & recreation | 2018 |
| Uogjlyke Ltd | Wholesale & retail | 2025 |
| Urbanaloft Limited | Hospitality | 2003 |
| Urtm Trading Limited | Hospitality | 2020 |
| Vale Holiday Parks (C) Limited | Extraterritorial | 2023 |
| Vale Holiday Parks (J) Limited | Extraterritorial | 2023 |
| Vale Holiday Parks (T) Limited | Extraterritorial | 2023 |
| Vale Holiday Parks Limited | Hospitality | 2003 |