| GRV Services Ltd | Information & communication | 2026 |
| Gryphon Commodities Limited | Wholesale & retail | 2015 |
| Gryphon Property Limited | Construction | 2014 |
| Grzelczak Ltd | Health & social care | 2016 |
| GS Builders Southampton Limited | Construction | 2017 |
| GS Coaching Academy Ltd | Arts & recreation | 2025 |
| GS Finishing Ltd | Manufacturing | 2023 |
| GS Medical Staffing Limited | Health & social care | 2025 |
| GS Pharm Limited | Wholesale & retail | 2022 |
| GS Property Service 23 Ltd | Construction | 2023 |
| GS Rathor Ltd | Real estate | 2019 |
| GS Strategic Consultancy Ltd | Professional & scientific | 2023 |
| GS Transfers Ltd | Transport & logistics | 2024 |
| GS Xpress Ltd | Transport & logistics | 2013 |
| GS4SYS Limited | Information & communication | 2013 |
| GSA Solutions Ltd | Information & communication | 2025 |
| GSB Commercial Finance Limited | Professional & scientific | 2026 |
| GSB Contractors (Hampshire) Ltd | Construction | 2026 |
| GSB Drainage Ltd | Water & waste | 2025 |
| GSB Management Limited | Real estate | 2019 |
| GSG Properties Limited | Real estate | 2014 |
| GSL Solutions Ltd | Professional & scientific | 2024 |
| GSS Advisory Ltd | Professional & scientific | 2018 |
| GSS Investments Ltd | Real estate | 2012 |
| GSS Property Management Ltd | Real estate | 2018 |
| Gsyoung Limited | Professional & scientific | 2025 |
| GT Air Services Ltd | Manufacturing | 2014 |
| GT Broadcast Media Ltd | Information & communication | 2017 |
| GT Exterior Services Ltd | Administrative & support | 2023 |
| GT Prodone Limited | Wholesale & retail | 2019 |
| GTA Residential Ltd | Real estate | 2021 |
| GTA Security Ltd | Real estate | 2018 |
| GTG Engineering Services Ltd | Professional & scientific | 2019 |
| GTT Analytics Limited | Information & communication | 2018 |
| GTT Engineering Ltd | Manufacturing | 2025 |
| Guardian Technical Services Limited | Administrative & support | 2020 |
| Guardstar Limited | Professional & scientific | 2025 |
| Gugu for Life Limited | Health & social care | 2010 |
| Guided by Beacon Limited | Professional & scientific | 2026 |
| Guildford Gutter Cleaning Limited | Administrative & support | 2026 |
| Guildhouse Flats Management Company Limited(The) | Households | 1976 |
| Guillan Assessments & Surveys Ltd | Professional & scientific | 2025 |
| GUL Traders Imports & Exports Limited | Wholesale & retail | 2021 |
| Gulli Barber Ltd | Other services | 2023 |
| Gully Howard Limited | Real estate | 2008 |
| Gulmarg Limited | Real estate | 2016 |
| Gulwing Consultancy Ltd | Professional & scientific | 2021 |
| Gungho Bidco Limited | Financial services | 2021 |
| Gungho Midco Limited | Financial services | 2021 |
| Gungho Topco Limited | Financial services | 2021 |
| Gunn Family Properties Ltd | Real estate | 2024 |
| Gunn People Ltd | Administrative & support | 2026 |
| Gunna Collects Ltd | Wholesale & retail | 2026 |
| Gunners Mews Limited | Households | 2002 |
| Gunnvarn Security Limited | Administrative & support | 2025 |
| Gupta Property Investments Ltd | Real estate | 2020 |
| GUR Transport Top Ltd | Transport & logistics | 2025 |
| Gurdwara Khalsa Darbar (Southampton Sikh Resource Centre) CIC | Other services | 2021 |
| Gurney Marketing Limited | Other services | 2015 |
| Gurus Direct Ltd | Information & communication | 2020 |
| Guster Group Ltd | Construction | 2026 |
| Gustin Furrow Ltd | Professional & scientific | 2023 |
| Guthrie Hills & Marchant Ltd. | Real estate | 1998 |
| Gutoimaging Photography Limited | Other services | 2015 |
| Gutter and Garden Guys Limited | Professional & scientific | 2025 |
| GUY Howard Limited | Construction | 1997 |
| GUY Meredith Limited | Information & communication | 2002 |
| GVR Premium Travel Ltd | Transport & logistics | 2023 |
| GVV Arts Design Ltd | Other services | 2025 |
| GW GAS Ltd | Construction | 2015 |
| GW Net-Working Limited | Information & communication | 2002 |
| GW Private Travel Limited | Administrative & support | 2024 |
| Gweneth Estates Limited | Real estate | 1935 |
| GWN IT Services Limited | Information & communication | 2013 |
| GWP Solutions Ltd | Professional & scientific | 2025 |
| GXD Builders Limited | Construction | 2014 |
| Gyles Construction Limited | Construction | 1998 |
| Gym 24 Ltd | Arts & recreation | 2022 |
| Gym Panda London Ltd | Wholesale & retail | 2025 |
| Gynaechoice Limited | Health & social care | 2003 |
| Gyrosland Limited | Other services | 2021 |
| H & a Specialists Ltd | Professional & scientific | 2024 |
| H & B Rathor Properties Ltd | Real estate | 2026 |
| H & C Cleaning & Maintenance Ltd | Administrative & support | 2021 |
| H & C Insulation & Roofing Ltd | Construction | 2025 |
| H & C Property Solutions Ltd | Construction | 2025 |
| H & G Building Services Limited | Construction | 2015 |
| H & H Yachting Ltd | Education | 2021 |
| H & J Catering Limited | Real estate | 2005 |
| H & M Property Lettings Limited | Real estate | 2014 |
| H & S Plumbing and Tiling Ltd | Construction | 2021 |
| H Accessories Limited | Wholesale & retail | 2021 |
| H ALI Logistics Ltd | Wholesale & retail | 2026 |
| H Alkarnaz Ltd | Real estate | 2016 |
| H and G Khaira Properties Limited | Real estate | 2021 |
| H and J Property South Ltd | Real estate | 2026 |
| H and S Supermarket Ltd | Wholesale & retail | 2025 |
| H D Sprays Ltd | Wholesale & retail | 2020 |
| H Electrics Ltd. | Construction | 2013 |
| H F Developments (Southampton) Limited | Real estate | 2022 |