| GVO Wind NO. 24 Limited | London | 2014 |
| GVO Wind NO. 25 Limited | London | 2014 |
| GVO Wind NO. 27 Limited | London | 2014 |
| GVO Wind NO. 28 Limited | London | 2014 |
| GVO Wind NO. 29 Limited | London | 2014 |
| GVO Wind NO. 30 Limited | London | 2014 |
| GVO Wind NO. 31 Limited | London | 2014 |
| GVO Wind NO. 32 Limited | London | 2014 |
| GVO Wind NO. 35 Limited | London | 2015 |
| GVO Wind NO. 36 Limited | London | 2015 |
| GVO Wind NO. 39 Limited | London | 2015 |
| GVO Wind NO. 40 Limited | London | 2015 |
| GVO Wind NO. 41 Limited | London | 2015 |
| GVO Wind NO. 42 Limited | London | 2015 |
| GVO Wind NO. 43 Limited | London | 2016 |
| GVO Wind NO. 44 Limited | London | 2016 |
| GVO Wind NO. 5 Ltd | London | 2012 |
| GVO Wind NO. 6 Limited | London | 2012 |
| GVO Wind NO. 7 Limited | London | 2014 |
| GVO Wind NO. 9 Ltd | Edinburgh | 2011 |
| GVO Wind NO.2 Limited | London | 2012 |
| GVO Wind NO.3 Limited | London | 2012 |
| GVO Wind NO.4 (Mount Pleasant) Limited | London | 2012 |
| Gvo/Cme Wind NO. 17 Limited | London | 2014 |
| Gvo/Cme Wind NO. 18 Limited | London | 2014 |
| Gvuk CNC Ltd | Edinburgh | 2015 |
| GW Overseas Holdings Limited | London | 2022 |
| GW Wind Ltd | Barrow-In-Furness | 2011 |
| GWE Biogas Ltd | Towcester | 2008 |
| Gwenlais Solar Limited | London | 2022 |
| Gwent Farmers' Community Solar Partnership Limited | London | 2013 |
| GWO Cable Contractors Limited | Glasgow | 2021 |
| Gwoodservices: Limited | Redcar | 2025 |
| GWS Consult Ltd | London | 2025 |
| Gwyddelwern Bess Limited | Cardiff | 2023 |
| Gwyddelwern Energy Limited | London | 2023 |
| Gwynt Cymru Limited | Welshpool | 2003 |
| Gwynt Glas Offshore Wind Farm Limited | Houghton Le Spring | 2021 |
| Gwynt HV Ltd | Barry | 2025 |
| Gwynt MON CYF | Llanerchymedd | 2013 |
| Gwynt Y Gaer Cyfyngedig | Llanybydder | 2012 |
| Gwynt Y Glog CYF | Crymych | 2015 |
| Gwynt Y MOR Offshore Wind Farm Limited | Swindon | 1999 |
| Gwynt Y MOR Ofto Holdings Limited | London | 2013 |
| Gwynt Y MOR Ofto Intermediate Limited | London | 2013 |
| Gwynt Y MOR Ofto PLC | London | 2013 |
| Gwyntynni Limited | Crymych | 2015 |
| Gym Offshore One Limited | Swanley | 2010 |
| Gym Offshore Three Limited | Swanley | 2010 |
| Gym Offshore Two Limited | Swanley | 2010 |
| Gypsum Solar Farm Limited | Gatwick | 2016 |
| H & P Electrical Contractors Ltd | Chester | 2011 |
| H & W Wind Energy Ltd | Enniskillen | 2026 |
| H&H & Co Consultants Limited | Edinburgh | 2020 |
| H&H Wind Murnells Ltd | Ballyclare | 2014 |
| H&Mv Consultants Ltd | Grimsby | 2024 |
| H&R Mechanical and Combustion Services Ltd | London | 2026 |
| H&T Plumbing & Heating Limited | Waterlooville | 2020 |
| H. Ambler & Sons Limited | Bradford | 2010 |
| H. Noble & SON Ltd | Norwich | 2010 |
| H14 Energy Limited | St. Albans | 2014 |
| H2 British Hydrogen Ltd | London | 2018 |
| H2 Clean Energy (UK) Limited | London | 2025 |
| H2 Evolution Ltd | Hove | 2021 |
| H2 Green Ltd | Edinburgh | 2020 |
| H2 Teesside Limited | Sunbury On Thames | 2022 |
| H2 World Ltd | Bridgend | 2016 |
| H2010 Esco Limited | Blackburn | 2011 |
| H2C02 Ltd | Milford Haven | 2025 |
| H2ECO Ltd | London | 2010 |
| H2ECO Partnerships Limited | Wimborne | 2011 |
| H2O Power (MSC1) Ltd | St Albans | 2017 |
| H2O Power (MSC3) Ltd | St Albans | 2017 |
| H2O Power Generation Ltd | St. Albans | 2014 |
| H2O Power Ltd | St Albans | 2014 |
| H2O Power Towy Ltd | London Colney | 2013 |
| H2TERMINALS Limited | Rainham | 2024 |
| H2V Hydrogen Projects UK Ltd | Farnborough | 2022 |
| H2YDROGEN Ltd | Warwick | 2023 |
| H6 Energy Limited | Braintree | 2013 |
| H7 Energy Limited | Bristol | 2013 |
| HA002 Limited | Ware | 2014 |
| Habitat Energy Limited | London | 2017 |
| Hadair Limited | Solihull | 2017 |
| Hade Edge Energy Limited | Stoke-On-Trent | 2022 |
| Hadfield-Solutions Limited | Manchester | 2025 |
| Hadlow Solar Park Limited | London | 2013 |
| Hadrian Air Conditioning and Refrigeration Company Limited | Washington | 1985 |
| Hadrian Renewables Ltd | Hexham | 2012 |
| Haedus Solar Limited | Bristol | 2021 |
| Hafnia Energy Global Limited | Ipswich | 2021 |
| Hafodboeth CYF | Caerfyrddin | 2015 |
| Hafren Power Limited | Cardiff | 2010 |
| Hagshaw Hill 3 Ltd | Hawick | 2022 |
| Hagshaw Hill Repowering Ltd | Glasgow | 2018 |
| Hail Air Conditioning Ltd | Ipswich | 2016 |
| Hainsford Energy (Blyth Harbour) Limited | Chelmsford | 1991 |
| Halbeath Solar Ltd | Edinburgh | 2023 |
| Haldane Energy Project 1 Limited | London | 2023 |
| Haldane Energy Project 2 Limited | London | 2023 |