| G Morris Property Management Limited | Construction | 2007 |
| G T Compressors Limited | Manufacturing | 2001 |
| G&P Electrical Limited | Construction | 2006 |
| G.A. Contracts Limited | Professional & scientific | 2006 |
| G.A. Installation & Maintenance Limited | Construction | 1991 |
| G.C. & G.J. Folly Limited | | 1980 |
| G.D. Golding (Properties) Ltd. | Real estate | 1996 |
| G.F. Clark Limited | Wholesale & retail | 2003 |
| G.I.F.T. Martial Arts UK Ltd | Arts & recreation | 2007 |
| G.I.S. Industrial Services Limited | Extraterritorial | 1996 |
| G.S. Walker Building Limited | Construction | 1999 |
| G.T. Cannon Electrical Limited | Construction | 2003 |
| G.W. & A.E.Thomson Limited | Wholesale & retail | 1955 |
| G2 Travel Limited | Real estate | 1989 |
| Gainfern Limited | Real estate | 2001 |
| GAN Baran Enterprises Limited | Administrative & support | 1996 |
| Garden Pro Limited | Wholesale & retail | 2006 |
| Garden Service Limited | Other services | 2001 |
| GB (UK) Catering Limited | Hospitality | 2010 |
| GC Project Management Limited | Construction | 2001 |
| GDL Properties Ltd | Real estate | 2016 |
| GDS Couriers Limited | Transport & logistics | 2008 |
| Gelding Road (Apartments) Management Company Limited | Households | 2025 |
| GEM G Fitness Ltd | Health & social care | 2021 |
| Generics (U.K.) Limited | Manufacturing | 1981 |
| Genetex Solutions Ltd | Administrative & support | 2021 |
| Genius Property Limited | Real estate | 2003 |
| Geo,Ausden Limited | Wholesale & retail | 1960 |
| George Hammond Limited | Wholesale & retail | 1961 |
| Georgina PAY School of Dance Limited | Education | 2007 |
| Gerald Pepper Financial Management Limited | Financial services | 2001 |
| Gernon Properties Limited | Real estate | 2000 |
| Gerrard Beauty Solutions Limited | Professional & scientific | 1997 |
| Gerrard International Limited | Administrative & support | 1992 |
| Gestalt Coaching & Training Ltd | Education | 2002 |
| Getting There Limited | Wholesale & retail | 1999 |
| Gezzo Limited | Wholesale & retail | 2001 |
| GFM Financial Services Limited | Professional & scientific | 1989 |
| GFM Group Limited | Professional & scientific | 2007 |
| Gibson Motorcycles Limited | Wholesale & retail | 2018 |
| Gigalan Ltd | Construction | 2017 |
| Gilbert Chapman (Small Works) Limited | | 1985 |
| Gilbert Chapman Limited | | 1984 |
| Gilbertson & Page Limited | Manufacturing | 1898 |
| Gill Peer & Company Limited | Professional & scientific | 2007 |
| Ginger Bar Herts Ltd | Hospitality | 2020 |
| Ginger Monkey Ltd | Information & communication | 2004 |
| Ginger Sparks Ltd | Construction | 2019 |
| GJU Services Limited | Health & social care | 2016 |
| GKK Axiom Ltd | Financial services | 2026 |
| GKK Axiom Research Ltd | Information & communication | 2026 |
| Glazebrook Limited | Construction | 2005 |
| Glen Monarch Distillery Limited | Manufacturing | 2017 |
| Glevum Management Limited | Professional & scientific | 1997 |
| GLJ (Stevenage) Limited | Professional & scientific | 2013 |
| Global Telecom Limited | Information & communication | 1998 |
| Globe Pharmacy Ltd | Wholesale & retail | 1998 |
| GOA Solutions Ltd | Real estate | 2019 |
| Gobee Limited | Professional & scientific | 2007 |
| Goddard Doyle Limited | Professional & scientific | 2002 |
| Going Horizontal Publications Limited | Information & communication | 2008 |
| Gold Crest Motors Limited | Wholesale & retail | 1978 |
| Gold Front Limited | Hospitality | 2023 |
| Gold Star FSL LLP | | 2010 |
| Goldberg Consulting Ltd | Professional & scientific | 2016 |
| Goldcrest (UK) Limited | Wholesale & retail | 1995 |
| Goldcrown Maintenance Services Limited | Manufacturing | 1994 |
| Golden Sand Realtors Limited | Real estate | 2025 |
| Goldquest Limited | Professional & scientific | 1997 |
| Goldstar Fuel LLP | | 2010 |
| Goldwing Limited | Information & communication | 2000 |
| GOO Music Management Limited | Arts & recreation | 2004 |
| Goodford Haslam Limited | Transport & logistics | 1998 |
| Goodground Limited | | 1986 |
| Goodier Smith & Watts Limited | Professional & scientific | 1999 |
| Goodman Mould Tools Ltd | Extraterritorial | 2005 |
| Goodwood Joinery Limited | Manufacturing | 2002 |
| Gordon Shepherd Associates Limited | Financial services | 1995 |
| Gosmore Court (Edmonton) Management Company Limited | Households | 1986 |
| Gpjb Limited | Administrative & support | 2020 |
| Grace Management Limited | Information & communication | 2007 |
| Gradely Consultants Limited | Hospitality | 2000 |
| Graham & Taylor Limited | Wholesale & retail | 1961 |
| Graham Taylor Sales Limited | Wholesale & retail | 1997 |
| Great Britain Limited | Extraterritorial | 1997 |
| Great Hertford Estates Ltd | Real estate | 1994 |
| Great Saints Ltd | Information & communication | 2007 |
| Green Globe Consultancy Limited | Extraterritorial | 1990 |
| Green Village Curry Ltd | Hospitality | 2019 |
| Greenacres Club Management Limited | Professional & scientific | 1998 |
| Greenacres Holiday Park Limited | Hospitality | 1969 |
| Greenroom Gardening Limited | Administrative & support | 2006 |
| Grenrose Scaffolding (UK) Limited | Construction | 2003 |
| Grenville Wilson Developments Limited | Construction | 1972 |
| Grestol Limited | Financial services | 1986 |
| Griffin & Associates Limited | Professional & scientific | 2004 |
| Griffin Research and Consultancy Limited | Professional & scientific | 2007 |
| Grinace Ltd | Professional & scientific | 2000 |
| Gripping Yarns Films Limited | Information & communication | 2020 |
| Grosvenor Financial Management Limited | Professional & scientific | 1991 |