| Fulcrum Metals PLC | Bromsgrove | 2022 |
| Full Term Engineering Services Ltd | Falkirk | 2014 |
| Fullsharp Diamondtools Co., Ltd | Cambridge | 2025 |
| Furness Bros Ltd | Stockport | 2014 |
| Furness Petroleum Limited | London | 2016 |
| Furrer UK Ltd | London | 2015 |
| Fusion Energy Holding Ltd. | London | 2023 |
| Future Engineering Consultants Limited | Stromness | 2004 |
| Future Generations Group Ltd | Harrogate | 2024 |
| Future Global Energy Ltd | London | 2023 |
| Future Global Resources Limited | London | 2019 |
| Futurevolume Limited | Macclesfield | 1993 |
| G & B Finch Holdings Limited | Chelmsford | 1992 |
| G & T Consultancy Services Limited | Aberdeen | 2019 |
| G - Force Rope Access Specialists Ltd | Dundee | 2024 |
| G Ashwood Professional Driver Hire Ltd | Burnham-On-Sea | 2026 |
| G B Conveyor Services Ltd | Chesterfield | 2015 |
| G B Subsea Limited | Peterhead | 2014 |
| G Charlton Ltd | Ashington | 2020 |
| G Hall Offshore Services Limited | Durham | 2023 |
| G J Monk Limited | Malvern | 2002 |
| G M Hydratech Ltd | Inverurie | 2016 |
| G Milham Consultancy Limited | Haywards Heath | 2012 |
| G R J Enterprises Limited | | 2000 |
| G S Safety Management (SW) Ltd | Radstock | 2019 |
| G&V Brown Limited | Rugby | 2014 |
| G-Power 1 Group Company Ltd | Enfield | 2020 |
| G-Tag Ltd | Blackpool | 2018 |
| G. & B. Finch Limited | Essex | 1973 |
| G. C. Tech Limited | Invergordon | 2007 |
| G.A.M. MEC Services Ltd | Brechin | 2016 |
| G.A.S. Integrity Limited | Grimsby | 2008 |
| G.Junnier. Services Limited | Aberdeen | 2012 |
| G.M.B Limited | Belfast | 2016 |
| G.R. Allan Aggregates (Thorney) Limited | Peterborough | 2014 |
| G.W. Technical Services Limited | Glasgow | 1986 |
| G.Watson Technical Services Ltd. | Grangemouth | 2016 |
| G0METO Global Ltd | Bootle | 2026 |
| G2 Building Solutions Limited | London | 2025 |
| Gabof Limited | London | 2019 |
| Gabriel Subsea Services Ltd | Ilkley | 2014 |
| Gabrostrat Ltd | Manchester | 2024 |
| Gafco Commodoties Ltd | London | 2020 |
| Gafrimex Holdings Limited | Livingston | 2020 |
| Gaia Earth Sciences Limited | Essex | 2003 |
| Gaimal Consulting Ltd | London | 2014 |
| Gairloch Resources Ltd | Omagh | 2023 |
| Gairsty Quarry Ltd | Stromness | 2010 |
| Galantas Irish Gold Limited | Belfast | 1997 |
| Galatech Ltd | Godalming | 2016 |
| Galileo Global Technologies PLC | Whiteley | 2015 |
| Galileo Holdco 1 Limited | Whiteley | 2016 |
| Galileo Holdco 2 Limited | Whiteley | 2016 |
| Galileo Resources PLC | London | 2006 |
| Galileo Shinganda Limited | London | 2024 |
| Gallagher Aggregates Limited | Maidstone | 1988 |
| GALLIUM7 Mining Limited | London | 2020 |
| Gallop 9908 Ltd | London | 2015 |
| Gama UK Limited | Epsom | 2009 |
| Gamble and SON Limited | Norfolk | 2003 |
| Ganus Technology Limited | Carlisle | 1997 |
| GAR Consultancy Services Ltd. | Aberdeenshire | 2000 |
| Garbo Resource Solutions Limited | Godalming | 2015 |
| Gardner Consulting Ltd | Aberdeen | 2020 |
| Gareth Garside Electrical Limited | Rochdale | 2014 |
| Garnet & Topaz Ltd | Greenhithe | 2023 |
| Garrett Consultants Limited | Greenford | 2016 |
| Garry Fleming Safety Solutions Limited | Glasgow | 2013 |
| Gartgaff Enterprises Limited | London | 2017 |
| Garuda Energy Transition Limited | London | 2023 |
| Gary Mcinulty Limited | Newport | 2017 |
| GAS Exploration Finance Limited | Bridgend | 2012 |
| GAS Wells Ltd | Bournemouth | 2026 |
| Gasavant Africa Trading Ltd | Manchester | 2023 |
| Gasconsult Limited | Twickenham | 2000 |
| Gasex (Mining Engineers) Limited | Radstock | 1967 |
| Gasinvest Ltd | Manchester | 2025 |
| Gaskell Bros (WM. & C.) Limited | Warrington | 1963 |
| Gasmonte Limited | Isle Of Arran | 2011 |
| Gasol PLC | Birmingham | 2005 |
| Gasol Upstream Limited | Birmingham | 2013 |
| Gastech Systems Limited | Birmingham | 2007 |
| Gasway Ltd | London | 2025 |
| Gasx Energy Ltd | London | 2017 |
| Gaterok Ltd | Penge | 2006 |
| Gatt Marine Services Ltd | Peterhead | 2023 |
| Gazprom International UK Ltd. | London | 2011 |
| GB GEO Limited | Laurencekirk | 1999 |
| GB Petroleum Ltd | London | 2023 |
| GBA Engineering and Construction Limited | Burnham | 1997 |
| Gbfandcgroup Limited | Oldham | 2024 |
| GBH (Europe) Ltd | Hounslow | 2017 |
| GBN Trading, Exploration & Production (U.K.) Ltd | London | 2020 |
| GBS Engineering Ltd | Beccles | 2013 |
| GC NDT Inspection Services Ltd | Ashington | 2017 |
| Gcjl Services Ltd | Montrose | 2011 |
| GCM Energy Limited | London | 2025 |
| GCM Resources PLC | London | 2003 |
| GDA Africa Limited | Manchester | 2020 |
| GDC (International) Limited | South Kelsey | 2000 |