| Greenoak Construction Ltd | Construction | 2011 |
| Greenoak Consulting Ltd | Professional & scientific | 2025 |
| Greens Associates Limited | Administrative & support | 2012 |
| Greenway Anaesthesia Limited | Health & social care | 2023 |
| Gresham House Solar Distribution LLP | | 2015 |
| Gresham House Solar Generation I LLP | | 2015 |
| Gresham House Solar Parks I LLP | | 2015 |
| Gresham House Wind Energy 1 PLC | Energy | 2019 |
| Gresham House Wind Energy LP | | 2015 |
| Greta Mason Eventing Limited | Arts & recreation | 2019 |
| Grey Parrot Group Ltd | Financial services | 2021 |
| Greycat Systems Ltd | Information & communication | 2026 |
| Griffin Life Science Limited | Professional & scientific | 2009 |
| Ground Effect Limited | Professional & scientific | 2023 |
| Grounded Landscapes Ltd | Administrative & support | 2024 |
| Groundworks Technology Limited | Financial services | 2015 |
| Grove Farm Glamping Pods Limited | Hospitality | 2021 |
| Grovelands 88 Hailey Road (Witney) Management Company Ltd | Households | 2017 |
| Growth Budd Ltd | Information & communication | 2022 |
| Growth Network Group Ltd | Administrative & support | 2025 |
| Gryphondor Limited | Real estate | 2012 |
| GS Horse Trainer Limited | Other services | 2021 |
| GSM Automotive Holdings Limited | Professional & scientific | 2014 |
| GT Automotive England Ltd. | Wholesale & retail | 2006 |
| GT Composite Engineering Ltd | Professional & scientific | 2024 |
| GT Refinishing Limited | Wholesale & retail | 2022 |
| Gtxm Limited | Professional & scientific | 2018 |
| Gueuleton Pubs Limited | Hospitality | 2017 |
| Guideposts Trust Limited | Information & communication | 1976 |
| Guild House Residents Association Limited(The) | Real estate | 1982 |
| Gutterclear UK Limited | Administrative & support | 2012 |
| Guugy Limited | Information & communication | 2025 |
| GWK Enterprise Limited | Administrative & support | 2012 |
| GX Cardiomedical Ltd | Health & social care | 2025 |
| H & H Transport (UK) Ltd. | Transport & logistics | 2003 |
| H & M Khaleghi Properties Ltd | Real estate | 2017 |
| H & O'B Building Ltd | Construction | 2015 |
| H and J Farms (Kelmscott) Ltd | Agriculture & fishing | 2022 |
| H G Rand & Sons Limited | Agriculture & fishing | 2018 |
| H S Food Express Limited | Hospitality | 2023 |
| H&J Consultancy Ltd | Information & communication | 2023 |
| H&Ob Holdings Ltd | Financial services | 2021 |
| H&Ob Plumbing and Heating Ltd | Construction | 2021 |
| H20 Venture Partners (Chariot) LLP | | 2012 |
| H2O Venture Partners (Chariot Manager) LLP | | 2012 |
| H3LIX Health and Fitness Ltd | Arts & recreation | 2023 |
| Hackett (Oxford) Limited | Water & waste | 1994 |
| Hadraniel Consulting Limited | Professional & scientific | 2025 |
| Haematopathology Alliance Ltd. | Health & social care | 2023 |
| Hagon Consultancy Limited | Professional & scientific | 2018 |
| Hailey Community Woodland Limited | Agriculture & fishing | 2002 |
| Hailey Gardens Management Company Limited | Households | 2010 |
| Hainesinvest Limited | Financial services | 2025 |
| Hairail Limited | Transport & logistics | 2020 |
| Halen Investments | Financial services | 2021 |
| Hall & Ensom Cotswolds Ltd | Professional & scientific | 2015 |
| Hall Barn Holdings Ltd | Financial services | 2026 |
| Hall Laundry Services Limited | Other services | 2012 |
| Halls Garage (Sutton Courtenay) Limited | Wholesale & retail | 2015 |
| Halsey Moore Homes Ltd | Real estate | 2024 |
| Hamilton Homes Oxfordshire Limited | Real estate | 2026 |
| Hamilton Oak Ltd | Construction | 2023 |
| Hamish Mackie Property Limited | Real estate | 2019 |
| Hamish Mackie Sculpture Limited | Arts & recreation | 2003 |
| Hammond's Exterior Cleaning Ltd | Administrative & support | 2022 |
| Hanborough Holdings Limited | Professional & scientific | 2021 |
| Hanborough Medical Services Limited | Wholesale & retail | 2007 |
| Hand&Shears Inn Ltd | Hospitality | 2026 |
| Hannah Saunders Associates Ltd | Professional & scientific | 2023 |
| Hansonwood Property Solutions Ltd | Real estate | 2019 |
| Happy Feet Plus Limited | Health & social care | 2006 |
| Happy Home Lettings Limited | Extraterritorial | 2023 |
| Harcourt Geological Limited | Professional & scientific | 2014 |
| Harcourt Meadow Management Company Ltd | Other services | 2025 |
| Hardybee Limited | Other services | 2004 |
| Hare Press Limited | Manufacturing | 2021 |
| Hargs Solutions Ltd | Information & communication | 2015 |
| Harling Plastering Limited | Construction | 2015 |
| Harlow Way Residents Company Limited | Extraterritorial | 1986 |
| Harmora Ltd | Health & social care | 2023 |
| Harriben Limited | Real estate | 2019 |
| Harris Brothers Carpentry Ltd | Construction | 2015 |
| Harris-Keyte Ltd | Manufacturing | 2013 |
| Harvest Venues Limited | Hospitality | 2019 |
| Harvestway (Witney) Limited | Professional & scientific | 2005 |
| Harvestway Business Growth LLP | | 2006 |
| Haselhorst Associates Ltd | Professional & scientific | 2025 |
| Hatfield PCN Ltd | Health & social care | 2026 |
| Hatts Health Limited | Information & communication | 2020 |
| Hatts Holdings Ltd | Real estate | 2025 |
| Haughton Refrigeration & Air Conditioning Ltd | Manufacturing | 2002 |
| Haul and Porter Limited | Hospitality | 2020 |
| Hawkins & Hawkins Renovation Limited | Construction | 2013 |
| Hawkins House Management Company Limited | Households | 2000 |
| Hawthorne & Baker Co Ltd | Transport & logistics | 2017 |
| Haysham Limited | Construction | 2003 |
| Hayward Audio Co. Ltd | Manufacturing | 2026 |
| Hayward Technology Solutions Ltd | Information & communication | 2023 |
| Hazel Grove Innovations Limited | Real estate | 2024 |
| Hazel Tech Consultancy Services Ltd | Information & communication | 2019 |