| Geenspark Green Energy Limited | Bridgwater | 2025 |
| GEI Kilmux Limited | Stockport | 2019 |
| GEI Patrickston Limited | London | 2019 |
| Geini Limited | Lisburn | 2013 |
| Gelliwern Solar Limited | Kings Langley | 2012 |
| Gelvin Hydro Limited | Londonderry | 2013 |
| GEM Air Conditioning Limited | Portsmouth | 2019 |
| GEM Capital Ventures International Ltd | Brighton | 2015 |
| GEM Energy - for Business Group Limited | Durham | 2018 |
| Gempowearth Ltd | London | 2023 |
| Gems Electrical Ltd | Hayes | 2010 |
| Gen-Rent UK Ltd | Darlington | 2019 |
| Genairate Limited | Solihull | 2024 |
| Genbank Energy Limited | Chester | 2022 |
| Genelectrical Services Ltd | Whitstable | 2008 |
| Generation Station Limited | Clitheroe | 2014 |
| Generation X Energy Limited | Consett | 2012 |
| Generator Installation Services Limited | Robertsbridge | 2010 |
| Genesis Electrics Limited | Harlow | 2018 |
| Genesis Energy Ltd | London | 2009 |
| Genesis Energy Solutions Ltd. | Leicester | 2016 |
| Genesis Photovoltaic Limited | Belfast | 2020 |
| Genesis PV Solutions Limited | Belfast | 2020 |
| Genex Power Solutions Ltd. | Norwich | 2013 |
| Genflex Energy Limited | Leeds | 2017 |
| Gengas Limited | Northampton | 1995 |
| Gennext Power Ltd | Ruislip | 2021 |
| Geocore (Kellwood) Ltd | Edinburgh | 2023 |
| Geocore Ltd | Edinburgh | 2021 |
| George Prior Engineering (Ipswich) Limited | Lowestoft | 1990 |
| George Prior Engineering Limited | Lowestoft | 1978 |
| George Stewart Limited | Inverness | 2011 |
| Georgia Energy Limited | Kingston Upon Thames | 2019 |
| Georgio’S Ltd | Rochford | 2020 |
| Geothermal Battery Ltd | London | 2022 |
| Geothermal Energy Ltd | Banchory | 2022 |
| Geothermal Engineering Limited | Redruth | 2008 |
| Geothermal Systems Limited | Corby | 2012 |
| Geothermal Wells UK Limited | Durham | 2024 |
| Gepg Kettering Ltd | Middlesbrough | 2023 |
| GER Utilities Ltd | Glasgow | 2022 |
| Gerard Homes Ltd | Wickford | 2000 |
| Gerlan Hydro Limited | Matlock Bath | 2011 |
| Germany Solar Limited | Newark | 2024 |
| Gervis Solar Limited | Christchurch | 2015 |
| GES SOLAR2 Limited | London | 2015 |
| GES SOLAR3 Limited | London | 2015 |
| GET Electric Ltd | London | 2019 |
| GET Electric Power Limited | Burnley | 2026 |
| GET GAS Power Limited | Burnley | 2026 |
| GET Generation Limited | Coventry | 2018 |
| GET Generation One Ltd | Coventry | 2022 |
| GET Green Solutions Ltd | Shirley, Solihull | 2021 |
| GET UK Solutions Limited | Sittingbourne | 2014 |
| GET Wired Installations Ltd | Cobham | 2009 |
| Getlink Projects 2 Limited | London | 2023 |
| Getricity Limited | London | 2024 |
| GF Alness Energy Ltd | London | 2025 |
| GF Carmarthen Energy Ltd | London | 2024 |
| GF Cell Barnes Energy Ltd | London | 2023 |
| GF Coventry North Solar Ltd | London | 2022 |
| GF Elgin Energy Ltd | London | 2024 |
| GF Elstree Energy Ltd | London | 2024 |
| GF Grendon Energy Ltd | London | 2024 |
| GF Kintore Energy Ltd | London | 2026 |
| GF Mansfield Energy Ltd | London | 2023 |
| GF Mybster Energy Ltd | London | 2024 |
| GF Nairn Energy Ltd | London | 2024 |
| GF Norrington Solar Ltd | London | 2022 |
| GF Norwich Energy Ltd | London | 2023 |
| GF Nuclear Limited | Tamworth | 2009 |
| GF Oxford Energy Ltd | London | 2023 |
| GF Power Peaking Limited | Birmingham | 2013 |
| GF Sellindge Energy Ltd | London | 2023 |
| GFB Lead Management Limited | Stirling | 2017 |
| GFF Ecogen Limited | Chatham | 2011 |
| GFG Energy Ltd | London | 2018 |
| GFI Northwick Ltd | Tamworth | 2023 |
| GFI Timet Ltd | Tamworth | 2023 |
| GFI Tregaron Ltd | Tamworth | 2023 |
| GFI73 Ltd | Tamworth | 2021 |
| GFM Whitelaw Electrical Ltd | Edinburgh | 2014 |
| GFP (Holdings) Limited | Tamworth | 2011 |
| GFP Didcot Limited | Tamworth | 2026 |
| GFP Trading Limited | Abingdon | 2015 |
| GFP-1T Limited | Tamworth | 2023 |
| GFP-2W Limited | Tamworth | 2023 |
| GFP-3R Limited | Tamworth | 2026 |
| GFP-4C Limited | Tamworth | 2026 |
| GG Electrical Contractors Ltd | Larne | 2013 |
| GGF Technologies Ltd | Glasgow | 2024 |
| Ggreenn Ltd | Glasgow | 2020 |
| Ggrenewables Limited | London | 2012 |
| GH Cable Jointing Ltd | Scarborough | 2025 |
| Ghana Goals Limited | Reading | 2025 |
| GHB Renewables Ltd | Irvine | 2023 |
| GHG Emissions Traders and Consultants Ltd | London | 2005 |
| GHH Group Holdings Ltd | Perth | 2016 |
| GHI Taodail Limited | Kendal | 2018 |
| Gianttech Ltd | Shepherds Bush | 2011 |