| General Industries MFG Ltd | Wholesale & retail | 2021 |
| Geotechnology Limited | Professional & scientific | 2008 |
| GET Gelled Ltd | Other services | 2025 |
| GET Yourself Noticed Limited | Wholesale & retail | 2002 |
| Glad Property Rentals Limited | Real estate | 2024 |
| Glamorgan Brickwork Ltd | Construction | 2011 |
| Glamorgan Business & Marketing Consultancy Ltd | Information & communication | 2018 |
| Glamorgan Eco Energy Limited | Energy | 2023 |
| Glamorgan Legacy Ltd | Professional & scientific | 2021 |
| Glamorgan Property Developments Limited | Real estate | 2023 |
| Glamorgan Services Limited | Construction | 1997 |
| Glamorgan Signs Ltd | Manufacturing | 2021 |
| Glan Y Waun Management Company Limited | Administrative & support | 2010 |
| Glasnant Contracting Limited | Transport & logistics | 2025 |
| Glenview Property Solutions Ltd | Real estate | 2021 |
| Glenville Properties Limited | Construction | 1992 |
| Glenwood Clicketts Tenby Limited | Administrative & support | 2011 |
| Glynfelin Estates Limited | Real estate | 2015 |
| Glynneath Financial Services Ltd | Financial services | 2009 |
| Glynneath Golf Club Limited | Education | 2021 |
| GM Carpentry & Construction Limited | Construction | 2025 |
| GMC Road & Plant Driving Services Ltd | Extraterritorial | 2014 |
| Gmmair Ltd | Administrative & support | 2022 |
| Gnoll Management Limited | Administrative & support | 2017 |
| Go Beyond Protection Limited | Financial services | 2026 |
| Go MAG Ltd | Hospitality | 2025 |
| Goal Enterprise (Neath) Ltd | Health & social care | 2015 |
| Goggled Ltd | Manufacturing | 2019 |
| Gogo Morriston Ltd | Hospitality | 2023 |
| Gogo Pizza Ltd | Hospitality | 2025 |
| Golden Grill Glyneath Limited | Hospitality | 2025 |
| Golding QS Services Limited | Construction | 2017 |
| Goodbox Limited | Mining & quarrying | 2000 |
| Goodhomes and Estates Limited | Real estate | 2025 |
| Goody 4 Paws Academy Ltd | Education | 2024 |
| Goody 4 Paws Ltd | Agriculture & fishing | 2016 |
| Gordon Benn Consultancy Ltd | Construction | 2025 |
| Gorsafle Ltd | Professional & scientific | 2016 |
| Gower Crafts & Artisans Limited | Arts & recreation | 2014 |
| Gower Technology Limited | | 1984 |
| Grace Giddings Property Limited | Real estate | 2026 |
| Grandadsbuilding&Roofing Ltd | Administrative & support | 2025 |
| Gravity Property Solutions Ltd | Construction | 2022 |
| Green Dragon Heating Ltd | Construction | 2022 |
| Green Haven Retreat Ltd | Health & social care | 2025 |
| Green Tree Joinery Ltd | Manufacturing | 2022 |
| Gregory GMS Ltd | Manufacturing | 2023 |
| Griffin Signs & Print Ltd | Manufacturing | 2022 |
| Griffiths Business Solutions Ltd | Financial services | 2021 |
| Griffiths Estates Ltd | Real estate | 2017 |
| Griffiths Property (South Wales) Ltd | Real estate | 2025 |
| Grinzing Limited | Transport & logistics | 2020 |
| Gritting Company (South Wales) Limited | Other services | 2013 |
| Groundhog (Holdings) Limited | Manufacturing | 2012 |
| Groundhog (U.K) Limited | Manufacturing | 1992 |
| Groundhog Sales Limited | Wholesale & retail | 1998 |
| Groundpeak Limited | Hospitality | 1989 |
| Groves Road Ltd | Hospitality | 2025 |
| Grow Roots Ltd | Real estate | 2020 |
| Grwp Limited | Administrative & support | 2025 |
| GSG Carpentry Ltd | Construction | 2025 |
| Guardian Angels Movie Limited | Information & communication | 2014 |
| Gwendraeth Valley Community Enterprise Limited | Real estate | 1985 |
| Gwilliam Group Limited | Real estate | 2024 |
| Gxnd Investments Ltd | Financial services | 2025 |
| Gxnd Limited | Wholesale & retail | 2020 |
| H Hopkins Properties Ltd | Professional & scientific | 2022 |
| H R Clothing (Cardiff) Limited | Wholesale & retail | 1994 |
| H. & H. Construction (Neath) Limited | Construction | 1980 |
| H.D. Owen Auto Repairs Limited | Wholesale & retail | 2003 |
| H.O.S. Hire Limited | Administrative & support | 2005 |
| Hairbylmd Ltd | Professional & scientific | 2026 |
| Hairyaxe Ltd | Agriculture & fishing | 2025 |
| Halcyon Environmental Limited | Administrative & support | 2021 |
| Hale Energy Ltd | Energy | 2019 |
| Hale Homes (Wales) Ltd | Construction | 2008 |
| Hamptons Cars Limited | Wholesale & retail | 2023 |
| Hanaran Properties Ltd | Real estate | 2017 |
| Hanell Limited | Real estate | 2001 |
| Happy House Properties Ltd | Administrative & support | 2023 |
| Harcourt Colourprint Ltd | Manufacturing | 2024 |
| Hardy's Delicacy Ltd | Hospitality | 2022 |
| Harold Davies Monumental Masons Limited | Other services | 2019 |
| Harpers Hair (Llanelli) Ltd | Other services | 2024 |
| Hart Group Properties Ltd | Real estate | 2023 |
| Havbo Consulting Limited | Professional & scientific | 2019 |
| Haven Children's Homes Ltd | Health & social care | 2023 |
| Haven Home Care (UK) Limited | Health & social care | 2014 |
| HAW & SON Property and Garden Services Ltd | Administrative & support | 2024 |
| Hawkes Brothers Home Furnishings Limited | Wholesale & retail | 2025 |
| Hawkes Brothers Joinery Co Ltd | Manufacturing | 2023 |
| Hawthorn Hedge Properties Ltd | Real estate | 2025 |
| Hayeburn Properties Limited | Households | 2019 |
| HD Events Ltd | Administrative & support | 2019 |
| HD23 Developments Ltd | Real estate | 2025 |
| HDJ Performance Limited | Professional & scientific | 2015 |
| Health IS One Community Ltd | Health & social care | 2021 |
| Heat Team (South Wales) Ltd | Construction | 2022 |
| Helen Stephens Development Ltd | Professional & scientific | 2014 |
| Helling Property Services Limited | Administrative & support | 2024 |