| GVT Plant Limited | Administrative & support | 2022 |
| Gwasanaethau Coed Starling Cyfyngedig | Administrative & support | 2024 |
| Gwendraeth Valley Carpets Limited | Wholesale & retail | 2011 |
| Gwendraeth Valley Tarmacadam Limited | Construction | 2022 |
| Gwenllian Court Hotel Limited | Hospitality | 2006 |
| Gwernllwyn Leisure Limited | Health & social care | 1982 |
| Gwersyll Y Glowyr Limited | Hospitality | 2024 |
| H & K (Swansea) Limited | Real estate | 2020 |
| H Ikram Properties Ltd | Real estate | 2017 |
| H J Lettings (Wales ) Ltd | Real estate | 2024 |
| H V F Valves Limited | Wholesale & retail | 2023 |
| H. J. Phillips & SON Limited | Wholesale & retail | 1982 |
| H.G.V. Medicals Ltd | Health & social care | 2022 |
| H.T. Structures Limited | Manufacturing | 2002 |
| H2O Heating and GAS Services Limited | Construction | 2005 |
| Hafod Design Ltd | Professional & scientific | 2021 |
| HAJ Properties Limited | Real estate | 2024 |
| Handmade in Wales Limited | Manufacturing | 2013 |
| Handy Entertainment UK Limited | Arts & recreation | 2023 |
| Hanhas Limited | Real estate | 2026 |
| Hanna Estall Interpreting Ltd | Professional & scientific | 2008 |
| Hannon Commercial Property Ltd | Real estate | 2014 |
| Happy Soul Community Ltd | Education | 2024 |
| Happy Soul Group Ltd | Education | 2023 |
| Haque Medicals Ltd | Health & social care | 2015 |
| Harfoot Investments Limited | Administrative & support | 2024 |
| Harper Express Ltd | Transport & logistics | 2020 |
| Harries & Sons Limited | Hospitality | 2026 |
| Harries Automation & Control Limited | Manufacturing | 1995 |
| Harris Contracting Ltd | Construction | 2025 |
| Harrys Hogroast and Caterers Limited | Hospitality | 2024 |
| Hart Property Services and Maintenance Ltd | Administrative & support | 2025 |
| Hartleys Select Properties Ltd | Hospitality | 2024 |
| Hartwell’S Joinery & Stairs Ltd | Construction | 2025 |
| Hawk Environmental Solutions Ltd | Administrative & support | 2020 |
| Hayhurst Wealth Management Limited | Professional & scientific | 2016 |
| Hayley T Wheeler Ltd | Other services | 2020 |
| Health Momentum Ltd | Health & social care | 2021 |
| Heard Learning Limited | Education | 2026 |
| Heat Pumps South Wales Ltd | Construction | 2025 |
| Heat Saving Specialists Ltd | Construction | 2024 |
| Help Wrong Fuel Ltd | Wholesale & retail | 2020 |
| Heol Y Meinciau 1966 Limited | Extraterritorial | 2015 |
| Hephaestus Engineering Limited | Professional & scientific | 2018 |
| HER Homely Homes Ltd | Real estate | 2025 |
| Hiatus Coffee Limited | Wholesale & retail | 2023 |
| Hidar Limited | Construction | 2022 |
| Hidlo Filtration Ltd | Water & waste | 2004 |
| High Tide Limited | Hospitality | 2025 |
| Hinterland Films 2 Limited | Information & communication | 2014 |
| Hinterland Films 3 Limited | Information & communication | 2015 |
| Hinterland Films Limited | Information & communication | 2012 |
| HJS Underfloor Heating Supplies Ltd | Wholesale & retail | 2017 |
| HLY Property Solutions Ltd | Real estate | 2024 |
| Hodge Motorsport Engineering Ltd | Manufacturing | 2018 |
| Holdens Wedding and Event Catering Ltd | Hospitality | 2013 |
| Holistic Healing Ltd | Health & social care | 2024 |
| Holistic Strength UK Ltd. | Arts & recreation | 2019 |
| Home James Transport Ltd | Transport & logistics | 2026 |
| Homeland Films Limited | Information & communication | 2009 |
| Homeoak Ltd | Construction | 2023 |
| Homes Well Ltd | Real estate | 2021 |
| Hooper Weston Trading Limited | Wholesale & retail | 2025 |
| Hopeducation (Healthy Opportunities for Personalised Enrichment) Community Interest Company | Education | 2026 |
| Hopematters Ltd | Education | 2012 |
| Hospitality Cabs Ltd | Transport & logistics | 2016 |
| House FLY Ltd | Real estate | 2021 |
| House of Mayflower Limited | Professional & scientific | 2017 |
| Housing & Law Consultancy Ltd | Professional & scientific | 2009 |
| Howells Wholesale Limited | Wholesale & retail | 2005 |
| HOZ Barber Ltd | Other services | 2026 |
| HPB Surgery Limited | Real estate | 2012 |
| Hsfusion Ltd | Information & communication | 2024 |
| Huadat Limited | Hospitality | 2013 |
| Hubert A.C.Thomas & Co.,Limited | Administrative & support | 1930 |
| Hugo Daisy Harrison Properties Ltd | Real estate | 2026 |
| Humble Coffi Co Ltd | Hospitality | 2019 |
| Hundal Convenience Stores Limited | Wholesale & retail | 2025 |
| Huntsman Corporation UK Limited | Manufacturing | 1994 |
| Huntsman Europe Limited | Financial services | 1998 |
| Huntsman Trustees Limited | Extraterritorial | 1994 |
| Husky Homes Limited | Real estate | 2024 |
| HUW Jeffreys & SON Limited | Construction | 2009 |
| HW Wealth Management Limited | Professional & scientific | 2024 |
| Hwyl a Sbri Ltd | Education | 2013 |
| Hyats Accountancy Limited | Professional & scientific | 2026 |
| Hydro Environmental Systems Limited | Water & waste | 2013 |
| Hyperlete Ltd | Administrative & support | 2015 |
| Hywel Davies Transport Limited | Transport & logistics | 2013 |
| I S Goose Ltd | Hospitality | 2017 |
| IAF Solutions Limited | Professional & scientific | 2026 |
| Iago Iaith CYF | Professional & scientific | 2026 |
| Iama Holdings Ltd | Real estate | 2022 |
| IAN Glanville Agricultural Engineer Ltd | Professional & scientific | 2026 |
| Idevelopelt Limited | Education | 2020 |
| Iggis Autos Limited | Wholesale & retail | 2012 |
| Ignite Software Limited | Information & communication | 2024 |
| IJ Cambria Scientific Ltd | Professional & scientific | 2003 |
| IJ Land Holdings Ltd | Real estate | 2026 |
| Ikram Developments Ltd | Construction | 2017 |