| GDJ Construction Management and Property Maintenance Ltd | Construction | 2025 |
| GEM Aberdare Limited | Other services | 2018 |
| Gentle Practice Ltd | Health & social care | 2024 |
| Geraint Hill (Car Sales) South Wales Limited | Wholesale & retail | 1983 |
| Gerry Hill (Haverfordwest) Limited | | 1973 |
| Gerry Hill Car Sales Limited | Extraterritorial | 1999 |
| GGP Law Ltd | Professional & scientific | 2012 |
| Gifted Origin Ltd | Wholesale & retail | 2024 |
| Glamorgan Security and Electrical Limited | Construction | 2016 |
| Glancynon Inn Ltd | Hospitality | 2022 |
| Glannant Consultancy Ltd | Information & communication | 2007 |
| Glannant Consulting LLP | | 2007 |
| GLC Courier Services Ltd | Transport & logistics | 2022 |
| Glitchbusters Limited | Wholesale & retail | 2017 |
| Globe Construction Limited | Construction | 2024 |
| Go Web IT Limited | Information & communication | 2023 |
| Goitre Tower Anthracite Limited | Professional & scientific | 1994 |
| Gokturkler Ltd | Transport & logistics | 2021 |
| Golden Bakey&Kebab Ltd | Hospitality | 2026 |
| Golden Star 2 Limited | Hospitality | 2024 |
| Golden Star 97 Ltd | Hospitality | 2017 |
| Goldenstar a Ltd | Hospitality | 2026 |
| Gorrel Equipment Solutions Limited | Administrative & support | 2011 |
| GP Carpentry Development & Building Services Limited | Construction | 2022 |
| GP Tech and Small Assets Ltd | Construction | 2024 |
| GPJ Property Solutions Ltd | Real estate | 2023 |
| Graeme John Limited | Professional & scientific | 2010 |
| Graig Developments Limited | Construction | 2018 |
| Grand Accounting Limited | Professional & scientific | 2001 |
| Grand Taps Limited | Wholesale & retail | 2007 |
| Green Valley Tuning Ltd | Wholesale & retail | 2023 |
| Greener GAS Plumbing & Heating Limited | Construction | 2021 |
| Greenlands Asset Holdings Ltd | Real estate | 2024 |
| Grey Trees Brewery Limited | Manufacturing | 2013 |
| GRL Wealth Management Ltd | Professional & scientific | 2021 |
| Growland UK Ltd | Wholesale & retail | 2026 |
| Gsbm Ltd | Health & social care | 2020 |
| Gurney Holdings Ltd | Hospitality | 2023 |
| Guru Nanak Food Investments Ltd | Hospitality | 2024 |
| GWR Motors Limited | Wholesale & retail | 2009 |
| H.P. Price Cynon Valley Limited | Wholesale & retail | 1999 |
| H2O Water Technologies Ltd | Water & waste | 2019 |
| Half Soaked Laundry Services Ltd | Other services | 2025 |
| Halo Security Ltd | Administrative & support | 2020 |
| Haltor Ltd | Health & social care | 2022 |
| Hamilton Living Ltd | Real estate | 2023 |
| Hammond (ECS) Limited | Construction | 1997 |
| Hancockhealthcare Limited | Health & social care | 2024 |
| HAO HUI Limited | Hospitality | 2021 |
| Happy Paws Veterinary Clinic Limited | Professional & scientific | 2023 |
| Harp Electrical Contractors Ltd | Construction | 2020 |
| Harry & Co. Holdings LLP | | 2024 |
| Hayes and Hartrey Limited | Real estate | 2026 |
| HCT Consulting Limited | Professional & scientific | 2015 |
| Headaway (Europe) Limited | Extraterritorial | 2000 |
| Hearts of the Valleys Ltd | Other services | 2025 |
| Helloa Properties Ltd | Real estate | 2023 |
| HF Lloyd UK Ltd | Real estate | 2025 |
| HG Civils & Housing Ltd | Construction | 2018 |
| Highline Rigging Ltd | Construction | 2026 |
| Hirwaun Energy Limited | Energy | 2016 |
| Hirwaun Enterprise Limited | Manufacturing | 2014 |
| Hirwaun Self Storage Ltd | Transport & logistics | 2019 |
| Hirwaun Takeaway Limited | Hospitality | 2025 |
| Hirwaun Travel Ltd | Administrative & support | 2023 |
| Hirwaun Ymca | Administrative & support | 2018 |
| HM Services Contractors Ltd | Construction | 2020 |
| Holder Property Services Limited | Real estate | 2003 |
| Holiday With Katy & Dean Ltd | Administrative & support | 2026 |
| Hollie Jones Finance Limited | Financial services | 2025 |
| Hopkins Legal Consulting Ltd | Professional & scientific | 2022 |
| Hoppy Finance Ltd | Professional & scientific | 2026 |
| Hot JAM Music CIC | Education | 2020 |
| Howells Carpentry and Home Improvements Limited | Construction | 2021 |
| Howlin’ Tig’S Ltd | Hospitality | 2021 |
| HR Davies Limited | Transport & logistics | 2003 |
| HRL Education Consultants Ltd | Education | 2024 |
| Hughes First Step Digger Ltd | Construction | 2020 |
| Hughes Roofing and Cladding Ltd | Construction | 2019 |
| Hulst Limited | Professional & scientific | 2006 |
| Hundal Thomas Consulting Ltd | Professional & scientific | 2019 |
| Hunter Digital Marketing Ltd | Information & communication | 2019 |
| Hussey's Autos Limited | Wholesale & retail | 2022 |
| Hywel Llewellyn Plant Hire Limited | Construction | 2006 |
| I D Accounting Services Limited | Professional & scientific | 2011 |
| I.T. Sorted Limited | Information & communication | 2006 |
| Ianto 5 Limited | Real estate | 2007 |
| Ignite GAS Services Ltd | Administrative & support | 2008 |
| Ignite Performance Automotive Ltd | Wholesale & retail | 2020 |
| Ignite Unlocking Potential Limited | Education | 2015 |
| ILJ Signalling Ltd | Construction | 2022 |
| Infinite Electrical Engineering Ltd | Construction | 2017 |
| Infinitive IT Ltd | Information & communication | 2014 |
| Infinity Aerial Media Ltd | Information & communication | 2016 |
| Infinity Security Services Ltd | Administrative & support | 2022 |
| Infinity Wales Electrical Ltd | Construction | 2024 |
| Inform CWM TAF Morgannwg C.I.C. | Health & social care | 2023 |
| Integrated Fencing Ltd | Construction | 2020 |
| Integrated Group Holding Ltd | Financial services | 2021 |
| Integrated Property Enterprise Ltd | Real estate | 2021 |