| Galaxy Plumbing and Property Maintenance Ltd | Construction | 2016 |
| Galieri Ltd | Wholesale & retail | 2018 |
| Galler Foods Ltd | Hospitality | 2025 |
| Gavin Home Improver Limited | Construction | 2016 |
| Gavin Jones Railway Limited | Construction | 2018 |
| Gazo Valeting Ltd | Other services | 2025 |
| Gellideg Foundation Community Association | Information & communication | 2003 |
| Gelligaer and Merthyr Commoners Ltd | Other services | 2019 |
| Gemtime Limited | Wholesale & retail | 2003 |
| GEN Tech Electric Ltd | Construction | 2021 |
| Geoquest Ltd | Professional & scientific | 2013 |
| George + Co. Ltd | Professional & scientific | 2016 |
| George Walsh Property Limited | Real estate | 2019 |
| Georgetown Boys' and Girls' Club | Arts & recreation | 2012 |
| Gerwyn Davies & Daughter Ltd | Construction | 2024 |
| GES Flooring Ltd | Construction | 2019 |
| GET Stuft Limited | Hospitality | 2016 |
| Gethin House Limited | Hospitality | 2024 |
| Gethin MTB Ltd | Arts & recreation | 2011 |
| Getstuft Brunch and Beyond Ltd | Hospitality | 2025 |
| Gibbsy Ltd | Wholesale & retail | 2025 |
| Giles & Sons Rail Limited | Construction | 2016 |
| Gisa Properties Ltd | Extraterritorial | 2023 |
| GJW Design Limited | Professional & scientific | 2013 |
| Glamorganshire Hawking | | 1998 |
| Glebeland Fish Bar Ltd | Hospitality | 2026 |
| GLM Engineering Ltd | Professional & scientific | 2023 |
| Global Reach Security Training Limited | Administrative & support | 2015 |
| GMP Carpets & Flooring Ltd | Construction | 2025 |
| GNB (Merthyr) Limited | Construction | 2021 |
| GNB (South Wales) Limited | Construction | 2009 |
| Go Figure Accountancy Limited | Professional & scientific | 2016 |
| Good to EAT Ltd | Hospitality | 2021 |
| Good Years Trading Limited | Wholesale & retail | 2018 |
| GR Welding Ltd | Construction | 2022 |
| Graft Contracting Ltd | Construction | 2021 |
| Graft Heating and Building Services Ltd | Construction | 2008 |
| Graft Projects Lettings Limited | Real estate | 2019 |
| Graft Projects Limited | Construction | 2015 |
| Graft Rail Ltd | Transport & logistics | 2024 |
| Grahame Hill Limited | Construction | 2007 |
| Green Engineering Services Limited | Professional & scientific | 2004 |
| Green Light Property Holdings Ltd | Construction | 2025 |
| Green Light Rail & Construction Ltd | Construction | 2023 |
| Greenstar Group Limited | Professional & scientific | 2007 |
| Greenstar Property Rental Limited | Real estate | 2007 |
| Griffiths Fencing & Landscaping Limited | Construction | 2012 |
| Griffs Removals & Renovations Ltd | Construction | 2020 |
| Growing Space | Health & social care | 1997 |
| GS Williams Ltd | Construction | 2025 |
| GTH Consrtuction (Wales) Ltd | Construction | 2014 |
| GTH Developments Ltd | Real estate | 2016 |
| Guest Functions & Weddings Ltd | Hospitality | 2023 |
| Gurnos Fish Bar Limited | Hospitality | 2015 |
| GV 17 Limited | Hospitality | 2024 |
| Gweld Y BYD CYF | Information & communication | 2026 |
| Gwenever Limited | Real estate | 2017 |
| Gwyn-May Financial Advisors Ltd | Financial services | 2013 |
| Gym PIG Ltd | Wholesale & retail | 2025 |
| H & H Property Rental Ltd | Real estate | 2021 |
| H&R Lettings Limited | Real estate | 2018 |
| H&R Property Holdings Limited | Real estate | 2016 |
| H&Wdirect Limited | Wholesale & retail | 2025 |
| Hajdax Pet Services Ltd | Agriculture & fishing | 2022 |
| Halo Aesthetics Wellness and Trauma Clinic Ltd | Other services | 2024 |
| Halo Support Ltd | Information & communication | 2019 |
| Harcon Properties Limited | Real estate | 2019 |
| Harcon Solutions Ltd | Other services | 2017 |
| Hard Core Fitness & Movement Limited | Arts & recreation | 2022 |
| Hareva Construction Ltd | Construction | 2019 |
| Harp Funeral Services Limited | Other services | 2005 |
| Harp Memorial Services Ltd | Other services | 2018 |
| Harremil Consultancy Ltd | Professional & scientific | 2021 |
| Harri J'S Hardware Ltd | Wholesale & retail | 2023 |
| Harrington & Gray Limited | Construction | 2022 |
| Harrogate Medical Limited | Manufacturing | 2023 |
| Harrys Sandwich Bar Limited | Hospitality | 2011 |
| Harvey’S Pizza Limited | Hospitality | 2026 |
| Hawke Rail Ltd | Construction | 2018 |
| Hawthorn Care Properties Limited | Real estate | 2017 |
| HBH Properties Ltd | Real estate | 2019 |
| Health 2 Employment (H2E) C.I.C. | Administrative & support | 2015 |
| Heat Vision Ltd | Construction | 2024 |
| Heatflo Ltd | Construction | 2026 |
| Heathome (UK) Limited | Construction | 2014 |
| Heathside Engineering Limited | | 1981 |
| Heritage Health Organics Ltd | Manufacturing | 2015 |
| Heritage Medical Limited | Wholesale & retail | 2002 |
| HFA Properties and Developments Limited | Real estate | 2021 |
| Highcroft Housing Ltd | Real estate | 2025 |
| Highfield Holiday Homes Ltd | Hospitality | 2025 |
| Highfield Property Group Ltd | Construction | 2018 |
| Hill Ponies of Wales Society Ltd | Information & communication | 2010 |
| Hills & Bailey Limited | Transport & logistics | 1972 |
| Hitchings & Thomas Limited | Wholesale & retail | 2008 |
| Holiday World International Travel Limited | Administrative & support | 1971 |
| Home & DRY (Merthyr Tydfil) Limited | Construction | 2007 |
| Honey Combes Hair Ltd | Other services | 2024 |
| Honorata Studio Photography Ltd | Professional & scientific | 2023 |
| Hopes Rail Limited | Construction | 2016 |