| Gacerit Limited | Health & social care | 2019 |
| Galata Ltd | Hospitality | 2024 |
| Galleria SUB Ltd | Hospitality | 2024 |
| Gallions Place Management Company Limited | Households | 2001 |
| Galvani Bioelectronics Limited | Professional & scientific | 2016 |
| Galvany Developments Ltd | Manufacturing | 2017 |
| Galvany Pharma Limited | Manufacturing | 2022 |
| Gameful Consulting Ltd | Professional & scientific | 2025 |
| Games Rating Authority | Administrative & support | 1989 |
| Gandhi Sons and Daughters Limited | Health & social care | 2022 |
| Ganea Services Ltd | Construction | 2018 |
| GAO Express Stevenage Limited | Hospitality | 2024 |
| Garage Doors R US Limited | Construction | 2023 |
| Garage RCS Ltd | Wholesale & retail | 2026 |
| Gardener Steel Ltd | Wholesale & retail | 2016 |
| Gardenscapes Landscaping Ltd | Administrative & support | 2022 |
| Garrard Building and Construction Limited | Construction | 1981 |
| Garrard Developments Limited | Construction | 1996 |
| Garthlands Property Services Ltd | Real estate | 2024 |
| Gary Allen Holdings Ltd | Real estate | 2023 |
| GAS 24 Limited | Construction | 2004 |
| GAS Chase Limited | Construction | 2024 |
| GAS2885 Limited | Transport & logistics | 2013 |
| Gate Housing Services Limited | Real estate | 2019 |
| Gate Leak Detection Limited | Construction | 2022 |
| Gateway 1000 Management Company Limited | Real estate | 2006 |
| Gavin Mansfield Limited | Construction | 2017 |
| GB Buildstore Hertfordshire Ltd | Construction | 2012 |
| GB Mowers Limited | Other services | 2019 |
| GC Sports Ltd | Education | 2016 |
| GCE Cleaning Ltd | Administrative & support | 2022 |
| GCE Herts Cleaning Ltd | Administrative & support | 2024 |
| Gcedimaculangan Services Ltd | Health & social care | 2022 |
| Gcis (UK) Holdings Limited | Financial services | 2024 |
| Gcis (UK) Limited | Information & communication | 2001 |
| Gckb Property Limited | Construction | 2023 |
| GCL Holdco Limited | Financial services | 2024 |
| GD Timber Craft Limited | Construction | 2016 |
| GDM Building Solutions Ltd | Construction | 2016 |
| GE Medical UK Limited | Health & social care | 2021 |
| GEA Property Holdings Ltd | Real estate | 2023 |
| Gechza Ltd | Financial services | 2025 |
| GEE Cards Ltd | Information & communication | 2025 |
| Gehen Construction Management Ltd | Construction | 2023 |
| GEL Original Limited | Professional & scientific | 2015 |
| Gelu T Logistics Ltd | Transport & logistics | 2018 |
| GEM Insight Ltd | Professional & scientific | 2025 |
| Gemini Print Services Limited | Manufacturing | 2010 |
| Gemm Care Ltd. | Health & social care | 2015 |
| Genetics Gymnasium Ltd | Extraterritorial | 2025 |
| Gentle Bridge Care Ltd | Health & social care | 2026 |
| Gents Cuts Ltd | Other services | 2012 |
| GEO Padel Limited | Manufacturing | 2025 |
| Geobet Ltd | Construction | 2021 |
| Geoffrey Reuters Consulting Ltd | Information & communication | 2019 |
| George HSE Training & Consultancy Ltd | Construction | 2025 |
| George Vincent Investment Limited | Real estate | 2018 |
| Georgia's Wonderland Limited | Arts & recreation | 2023 |
| Geotech Solutions UK Limited | Health & social care | 2025 |
| Geotronix Ltd | Information & communication | 2022 |
| Gesgb | Other services | 2000 |
| Gesgb Conferences Limited | Administrative & support | 1991 |
| GET Going With Nadia Limited | Wholesale & retail | 2016 |
| Gezana Properties Ltd | Real estate | 2026 |
| GFA Properties Ltd | Real estate | 2026 |
| GG Stevenage Ltd | Other services | 2019 |
| GGF Autos Ltd | Wholesale & retail | 2018 |
| GH Control Solutions Ltd | Professional & scientific | 2014 |
| GHM Properties Ltd | Real estate | 2021 |
| Ghostthebarber Ltd | Wholesale & retail | 2024 |
| Giant Strides Pharma Ltd | Other services | 2019 |
| Gibson Family Properties Limited | Real estate | 2023 |
| Gifts of Africa Ltd | Manufacturing | 2014 |
| Giftshopuk Ltd | Wholesale & retail | 2022 |
| Gilbert Taylor Fitness Ltd | Arts & recreation | 2025 |
| Gilston Meadows Management Corporation Limited | Households | 2000 |
| Gilston Park Estate Limited | Households | 2017 |
| Gilston Park House (Gilston) Management Company Limited | Households | 1999 |
| Ginger Beer Productions Limited | Information & communication | 2016 |
| Ginger Events Management Ltd | Arts & recreation | 2019 |
| Giraffe Property Management Ltd | Real estate | 2019 |
| Girls Pro Football Club | Arts & recreation | 2024 |
| GJ Auto Repairs Ltd | Wholesale & retail | 2019 |
| GL Investment Management Limited | Administrative & support | 2010 |
| Glam and GLO Holdings Ltd | Other services | 2018 |
| Glam Headquarters Ltd | Other services | 2024 |
| Glamis Close Limited | Households | 2020 |
| Glas Energy Limited | Professional & scientific | 2018 |
| Glaxo Group Limited | Professional & scientific | 1935 |
| Glaxo Wellcome UK Limited | Wholesale & retail | 1950 |
| Glaxosmithkline Intellectual Property (NO.2) Limited | Financial services | 2012 |
| Glaxosmithkline Intellectual Property (NO.3) Limited | Professional & scientific | 2018 |
| Glaxosmithkline Intellectual Property (NO.4) Limited | Other services | 2018 |
| Glaxosmithkline Intellectual Property Development Limited | Financial services | 2012 |
| Glaxosmithkline Intellectual Property Holdings Limited | Financial services | 2012 |
| Glaxosmithkline Intellectual Property Limited | Financial services | 2012 |
| Glaxosmithkline Intellectual Property Management Limited | Administrative & support | 2011 |
| Gleam Stream Window Cleaning Services Ltd | Administrative & support | 2025 |
| Glebe Aggregates Ltd | Wholesale & retail | 2021 |
| Glebe Construction Management Services Ltd | Construction | 2023 |