| Hatford Enterprises Ltd | Agriculture & fishing | 2008 |
| Hawkstone Park Limited | Hospitality | 2002 |
| Haynes Close Management Company Limited | Households | 2011 |
| HDC Holdings Limited | Professional & scientific | 2008 |
| Health Huddle Community Interest Company | Information & communication | 2025 |
| Healthwise Supplies Ltd | Hospitality | 2025 |
| Hearts and Heads Limited | Education | 2022 |
| Heatmaster Fires Limited | | 1990 |
| Hellawell Motors Ltd | Wholesale & retail | 2024 |
| Hellidon Lakes Limited | Hospitality | 2018 |
| Hello From ME Ltd | Information & communication | 2023 |
| Henry J H Allenby Ltd | Administrative & support | 2021 |
| Hewes Supply Chain Services Ltd | Transport & logistics | 2019 |
| Hingebray Ltd | Real estate | 2013 |
| Hived Consultants Limited | Professional & scientific | 2021 |
| HJ Bevan Estates Ltd | Real estate | 2024 |
| Hmmr Ltd | Real estate | 2024 |
| Honest Energies Ltd | Construction | 2025 |
| Honest Solar Ltd | Construction | 2022 |
| Hong Kong House (Faringdon) Ltd | Hospitality | 2026 |
| Hope and Comfort Care Limited | Health & social care | 2022 |
| Hothouse Properties Limited | Construction | 2020 |
| Howbury Developments Ltd. | Professional & scientific | 1997 |
| Hrknowhow Limited | Professional & scientific | 2006 |
| HRS Management Limited | Professional & scientific | 2009 |
| Hugh Smith & Associates Ltd | Administrative & support | 2003 |
| Humpty Dumpty Childcare Limited | Education | 2003 |
| Hustlers Wing Ltd | Manufacturing | 2016 |
| I Gustosi Ltd | Hospitality | 2018 |
| I&M Fire Consultancy Ltd | Professional & scientific | 2023 |
| Iffley Road Flats Limited | Real estate | 1975 |
| Illac Limited | Information & communication | 2002 |
| Imperial Restoration & Construction Ltd | Construction | 2013 |
| IN House IQ Ltd | Professional & scientific | 2025 |
| Injection Moulding Tools Limited | Manufacturing | 1996 |
| Insightml Ltd | Information & communication | 2024 |
| Inspired Bespoke Services Ltd | Education | 2024 |
| Inspired Tutoring Services Ltd | Education | 2023 |
| Integrity Fire Doors Ltd | Construction | 2024 |
| Intensive Marketing Limited | Professional & scientific | 2018 |
| Inter Mediate Group Limited | Professional & scientific | 1990 |
| Inter Mediate Property Limited | Real estate | 1988 |
| Inter Rested Limited | Professional & scientific | 1998 |
| Interesting Hotels Limited | Hospitality | 2013 |
| Interesting Poets House Limited | Hospitality | 2000 |
| Iona Hilleary Ltd | Administrative & support | 2018 |
| Ippos Construction Limited | Construction | 2025 |
| Iprocess Limited | Information & communication | 2012 |
| Iptuc Business Services Ltd | Administrative & support | 2025 |
| Island Soapery Ltd | Manufacturing | 2017 |
| Istanbul Barbers Faringdon Ltd | Other services | 2024 |
| IVY Nook Homes Ltd | Real estate | 2022 |
| Ixora Hotel and Spa Limited | Hospitality | 1907 |
| J & L Property Construction Ltd | Construction | 2025 |
| J & P Civil Engineers Ltd | Construction | 2020 |
| J Godfrey & SON Ltd | Transport & logistics | 2004 |
| J J Stallard Ltd | Construction | 2018 |
| J Priest & Family Ltd | Administrative & support | 2020 |
| J R Staffing Limited | Health & social care | 2023 |
| J&S Channon Ltd | Real estate | 2025 |
| J3S IT Ltd | Information & communication | 2015 |
| Jackson & Browning Funeral Directors Ltd | Other services | 2018 |
| Jacobs-Solomon Ltd | Professional & scientific | 2025 |
| Jade Alpaca Ranch LLP | | 2018 |
| Jade Companies Ltd | Financial services | 2018 |
| Jake Arthur Hair Ltd | Other services | 2025 |
| Jasengine Ltd | Wholesale & retail | 2024 |
| Jim's Carpet Cleaning Limited | Administrative & support | 2014 |
| Jispark Ltd | Wholesale & retail | 2025 |
| JLC Carpenters Ltd | Manufacturing | 2019 |
| Jodie Newman Design Limited | Professional & scientific | 2025 |
| Journey Africa Ltd | Administrative & support | 2025 |
| Joy Frequency Ltd | Manufacturing | 2022 |
| JRB Restaurants Ltd | Hospitality | 2022 |
| Jrogers Properties Ltd | Real estate | 2025 |
| JSG IT Services Ltd | Information & communication | 2024 |
| Juice Moving Images Limited | Information & communication | 2007 |
| Just Results Bookkeeping Limited | Professional & scientific | 2021 |
| Just Results Ltd | Administrative & support | 1999 |
| Justcc Ltd | Construction | 2016 |
| Justin Spink Limited | Administrative & support | 2004 |
| K and a Trees Limited | Agriculture & fishing | 2025 |
| K&C Carpentry & Joinery Ltd | Other services | 2023 |
| K&C Catering Ltd | Hospitality | 2024 |
| K&C Waste Ltd | Water & waste | 2024 |
| Kdaf Designs Limited | Professional & scientific | 2010 |
| Kenia Limited | Public administration | 2023 |
| Ker-Ching Marketing Limited | Professional & scientific | 2011 |
| KES Ventures Ltd | Construction | 2017 |
| Kids OUT of Hours Limited | Education | 1998 |
| Kingdom & Co Limited | Real estate | 2014 |
| Kingdom Management Services Ltd | Real estate | 2016 |
| KK Equestrian Ltd | Wholesale & retail | 2022 |
| Klik Robotics Limited | Manufacturing | 2017 |
| KVM Studios Ltd | Arts & recreation | 2024 |
| L&S Faithworks Limited | Manufacturing | 2025 |
| Lacreme DE LA Creme Beaute Ltd | Wholesale & retail | 2011 |
| Langfords Management Limited | Households | 1997 |
| Langmead Associates Ltd | Professional & scientific | 2014 |
| Laschicas Ltd | Hospitality | 2021 |