| Tarifa Investments Limited | Real estate | 2017 |
| Tarporley Estates Limited | Professional & scientific | 2025 |
| TAW Properties Ltd | Real estate | 2024 |
| Taxa Ecology Ltd | Professional & scientific | 2021 |
| Tbanks Building Contractors Limited | Construction | 2016 |
| Team Mission AID Community Interest Company | Other services | 2026 |
| Teiars Hughes Tyres Ltd | Wholesale & retail | 2026 |
| THE Bangkok Limited | Hospitality | 2024 |
| THE Boatshed Sailmakers Limited | Wholesale & retail | 2013 |
| THE C Store and Post Bach Limited | Wholesale & retail | 2014 |
| THE Cliffs MN Ltd | Hospitality | 2026 |
| THE Eternal Forest Trust Limited | Other services | 2004 |
| THE Fitzrovia Centre Ltd | Manufacturing | 2016 |
| THE Forensic Psychology Agency Limited | Information & communication | 2003 |
| THE House Doctor North Wales Limited | Construction | 2023 |
| THE PEG and Mallet Limited | Hospitality | 2014 |
| THE Sea Company Lifestyle Limited | Wholesale & retail | 2022 |
| THE Ship Hotel Limited | Hospitality | 2005 |
| THE Ship Inn Llanbedrog Ltd | Hospitality | 2023 |
| THE Snack Shack in the Village Ltd | Hospitality | 2024 |
| THE Station Cafe & Tea Rooms Limited | Hospitality | 2005 |
| THE Summer Room Limited | Hospitality | 2021 |
| Thomas & Williams (Peirianneg Sifil) CYF | Construction | 2016 |
| Throne (GB) Limited | Professional & scientific | 2012 |
| Tiga Lima Ltd | Professional & scientific | 2019 |
| Timber Frame Suppliers Ltd | Manufacturing | 2025 |
| Tippi-Toes Dog Grooming Ltd | Other services | 2025 |
| TIR AC Eiddo LWH Land and Property CYF | Real estate | 2022 |
| Toft's Dining Rooms Ltd | Hospitality | 2010 |
| Tommo Construction Ltd | Construction | 2023 |
| Total Boat Sales Ltd | Wholesale & retail | 2017 |
| Total Door Solutions Limited | Construction | 2024 |
| Toy-Bocs-Teganau Limited | Wholesale & retail | 2023 |
| Transpose Media Limited | Education | 2023 |
| Tremfan Caravan Park Ltd | Hospitality | 2004 |
| Tremfan Lodge Park Ltd | Hospitality | 2019 |
| Tremfan Ltd | Hospitality | 2022 |
| Tremfan Properties Ltd | Real estate | 2023 |
| Triagwelti CYF | Real estate | 2016 |
| Tributes on the Hill Ltd | Arts & recreation | 2026 |
| TTR Solutions Limited | Information & communication | 2016 |
| TU Mewn Interiors Limited | Manufacturing | 2024 |
| Twankey's Laundry Ltd | Other services | 2017 |
| TWM Roofing/Roofline Ltd | Construction | 2023 |
| Twnti Ltd | Hospitality | 2026 |
| TY Coch Inn Limited | Hospitality | 2014 |
| TY Cynan Farm Ltd | Agriculture & fishing | 2023 |
| TY TOM CYF | Real estate | 2026 |
| Ty'N Llwyn Tree Services Limited | Other services | 2020 |
| Tyddyn Cwcallt Limited | Agriculture & fishing | 2016 |
| Tyddyn Isaf CYF | Hospitality | 2022 |
| Tyddyn Sachau Nurseries CYF. | Wholesale & retail | 2017 |
| Tyddyn Talgoch CYF | Hospitality | 2013 |
| TYN Y MUR Caravan Park Limited | Hospitality | 2018 |
| TYN Y Parc Holidays Ltd | Hospitality | 2023 |
| Tywod Esne CYF | Real estate | 2023 |
| UK Fire Safety Systems Limited | Administrative & support | 2024 |
| UK Firewood Processing Ltd | Agriculture & fishing | 2022 |
| Urura Moments Ltd | Arts & recreation | 2023 |
| Uwchlaw CYF | Professional & scientific | 2020 |
| Vape-Zilla Ltd | Wholesale & retail | 2025 |
| Vaughan Educational Consultants Ltd | Education | 2020 |
| Vedra Media Limited | Professional & scientific | 2015 |
| Video Receiving Centre Ltd | Administrative & support | 2022 |
| Villa Nautica Limited | Wholesale & retail | 2002 |
| Vintage and Retro Co Ltd | Wholesale & retail | 2018 |
| Vintage and Retro Paint Co Ltd | Other services | 2019 |
| W H Coatings Limited | Wholesale & retail | 2004 |
| W H Evans Cyfyngedig | Wholesale & retail | 2022 |
| W. Rickards Ltd | Extraterritorial | 2014 |
| W.Jones & Son(Nefyn)Limited | Wholesale & retail | 1961 |
| Walter Lloyd Jones Holdings Ltd | Real estate | 2022 |
| Walter Roberts Limited | Real estate | 2015 |
| Wellness Water Limited | Water & waste | 2018 |
| Westconsult Limited | Professional & scientific | 2017 |
| Wheaton Energy Limited | Professional & scientific | 2024 |
| Wildacre Trading Limited | Agriculture & fishing | 2012 |
| Williams Floors Limited | Construction | 2019 |
| WJ Evans A'I Gwmni (Ynys Enlli) CYF | Manufacturing | 2018 |
| Wolf Owen CYF | Households | 2025 |
| Wolves of the Sky Ltd | Arts & recreation | 2019 |
| Wompl Limited | Information & communication | 2023 |
| Wonderling Travel Limited | Administrative & support | 2010 |
| Wray Architects Ltd | Professional & scientific | 2020 |
| XVB-21 Ltd | Construction | 2018 |
| Y Castell(Pwllheli) Limited | Hospitality | 2012 |
| Y DEN Pwllheli CYF | Arts & recreation | 2016 |
| Y Gegin Fawr Ltd | Hospitality | 2022 |
| Y Golchdy CYF | Administrative & support | 2020 |
| Y Lion Hotel Limited | Hospitality | 2021 |
| Y Plas Coch CYF | Hospitality | 2014 |
| Y Sior CYF | Hospitality | 2026 |
| Y28 Leisure & Investments Ltd | Transport & logistics | 2019 |
| Ymddiriedolaeth Nant Gwrtheyrn | Education | 1999 |
| YMG Lafan CYF | Professional & scientific | 2024 |
| Ynni'R Eifl CYF | Construction | 2017 |
| YR HEN Felin - the Old Mill, BED & Breakfast Ltd | Hospitality | 2026 |
| ZED Motion Limited | Information & communication | 2022 |
| Zinc Abersoch Limited | Hospitality | 2012 |