| Tarian (Yswiriant) Cyfyngedig | Financial services | 1999 |
| TC Flavo Ltd | Wholesale & retail | 2022 |
| Tecstiliau Cwmni Buddiant Cymunedol | Manufacturing | 2019 |
| Tegfan Guesthouse Limited | Hospitality | 2019 |
| Teiars Gwynedd Tyres Ltd | Wholesale & retail | 2025 |
| Teiliau Bach Hydro Ltd | Energy | 2015 |
| Teithiau Menai CYF | Administrative & support | 2014 |
| Teledwyr Annibynnol Cymru CYF. | Other services | 1991 |
| Tesni Hughes Coaching Ltd | Other services | 2023 |
| TH Civil Design Ltd | Professional & scientific | 2012 |
| Thaidee Rides Ltd | Wholesale & retail | 2024 |
| THE Artisan Burrow Co. Ltd | Manufacturing | 2025 |
| THE Computer GUY Ltd | Information & communication | 2014 |
| THE Deep Creative Ltd | Professional & scientific | 2022 |
| THE Function Hub Ltd | Arts & recreation | 2018 |
| THE Glyntwrog Inn Ltd | Hospitality | 2016 |
| THE Little Wren Aesthetics and Beauty Ltd | Other services | 2019 |
| THE Nellie Chute Ltd | Administrative & support | 2016 |
| THE Orchid Fashion Company Limited | Wholesale & retail | 1992 |
| THE Snowdonia Holiday House Ltd | Arts & recreation | 2019 |
| THE Surfer Limited | Hospitality | 2009 |
| Theatr Bara Caws | Arts & recreation | 1997 |
| Think Menai Ltd | Information & communication | 2025 |
| Thomas & Jones (Glaziers) Limited | Wholesale & retail | 2003 |
| Thomas Skip and Plant Hire Ltd | Water & waste | 2012 |
| Thomcatt RGH Limited | Hospitality | 2019 |
| Tian Tian YOU YU Ltd | Hospitality | 2021 |
| TIN Sardines CYF | Arts & recreation | 2024 |
| TKA Holdings Limited | Financial services | 2025 |
| TOM & RAJ Jones Trust | Professional & scientific | 2014 |
| Tomos Design Ltd | Professional & scientific | 2017 |
| TP Agriculture Limited | Agriculture & fishing | 2023 |
| Trac 42 CYF. | Information & communication | 2021 |
| Traeth Gwyllt CYF | Arts & recreation | 2022 |
| Trefor Stores Ltd | Wholesale & retail | 2017 |
| Trev's Taxis Limited | Transport & logistics | 2018 |
| Trigonos | Education | 1996 |
| TRO Systems Limited | Professional & scientific | 2026 |
| Trydanol Energy Solutions CYF. | Professional & scientific | 2021 |
| Tryweryn Hydro Limited | Energy | 2012 |
| TWR Scaffolding Ltd | Construction | 2014 |
| TY Dyfodol Ltd | Health & social care | 2025 |
| TY Emrys CYF | Wholesale & retail | 2019 |
| TY Glyndwr Bunkhouse & Su's Cocktail Bar Limited | Hospitality | 2024 |
| TY Rhandir Mwyn CYF | Hospitality | 2024 |
| Ty'N YR Onnen Farm LLP | | 2011 |
| Tyddyn Berth CYF | Real estate | 2015 |
| TŶ Castell CYF | Hospitality | 2016 |
| ULC Ltd | Hospitality | 2026 |
| Underhill & SON Tree Surgery Limited | Administrative & support | 2013 |
| Unique Tint Ltd | Construction | 2017 |
| Urban Fabric Recruitment Limited | Administrative & support | 2022 |
| Utopia (Caernarfon) Ltd | Other services | 2012 |
| Valero Northridge Ltd | Transport & logistics | 2026 |
| Vantay Ltd | Wholesale & retail | 2025 |
| Vaynol Plumbing & Heating Ltd | Construction | 2013 |
| Vibrance Psychology and Consultancy Services Ltd | Health & social care | 2018 |
| Visageco Limited | Professional & scientific | 2025 |
| VMG Coaching Ltd | Other services | 2016 |
| Vy's Nail HD Ltd | Other services | 2024 |
| W.J.D Supplies Ltd | Administrative & support | 2025 |
| Wacky Wedge Cheese Company Ltd | Manufacturing | 2022 |
| Waterloo Building Services Limited | Construction | 2004 |
| Waterloo House Eryri Ltd | Wholesale & retail | 2023 |
| Wavell's 2 Limited | Financial services | 2017 |
| Wavell's Butchers Limited | Wholesale & retail | 2007 |
| Webber Marine Services Ltd | Agriculture & fishing | 2017 |
| Webblets Ltd | Real estate | 2024 |
| Weboneuk Limited | Information & communication | 2007 |
| Welcome Furniture EBT Limited | Administrative & support | 2021 |
| Welcome Furniture Group Limited | Manufacturing | 2016 |
| Welcome Furniture Ltd. | Manufacturing | 2008 |
| Welcome Holdings Limited | Manufacturing | 2009 |
| Wellbeing by Wren Limited | Health & social care | 2024 |
| Wendy Hughes Services Limited | Administrative & support | 2022 |
| West Coast Gifts (UK) Limited | Wholesale & retail | 2017 |
| Williams & Williams Network Services Ltd | Professional & scientific | 2018 |
| Winrow Solicitors Ltd | Professional & scientific | 2018 |
| Womens Lingerie Ltd | Wholesale & retail | 2022 |
| Wool Testing Authority (Europe) Limited | Professional & scientific | 2003 |
| WWS Inc Ltd | Information & communication | 2026 |
| WWS Incorporated Ltd | Information & communication | 2024 |
| Wyddfa AR LWY CYF | Manufacturing | 2020 |
| Wynnes Group Limited | Mining & quarrying | 2024 |
| Xperience Web Hosting Ltd | Information & communication | 2004 |
| Y Bartneriaeth Awyr Agored the Outdoor Partnership | Arts & recreation | 2011 |
| Y Beudy Ltd | Hospitality | 2025 |
| Y BWS Crwst CYF | Hospitality | 2023 |
| Y Clochdy CYF | Hospitality | 2019 |
| Y Cons CYF | Hospitality | 2026 |
| Y Fricsan Pizza CYF | Hospitality | 2024 |
| Y Gynghrair CYF. | Information & communication | 2008 |
| Y Stablau Limited | Hospitality | 2019 |
| Y Tren Bach Coch CYF | Professional & scientific | 2024 |
| Y WAL Limited | Administrative & support | 2009 |
| Yellow Spider Media Ltd. | Professional & scientific | 2014 |
| Yeti Media Limited | Information & communication | 2014 |
| Ymddiriedolaeth Owen Jones CYF | Education | 2025 |
| Ymgynghoriaeth Liminal Cymru CYF | Professional & scientific | 2026 |
| Ynni Lleu CBC | Energy | 2019 |