| Hire & Construct Limited | Administrative & support | 2025 |
| Histon Station Management Limited | Households | 2020 |
| HJ Prop Ltd | Agriculture & fishing | 2017 |
| HN ELY Ltd | Real estate | 2023 |
| HNB Ltd | Real estate | 2024 |
| Hnto Limited | Professional & scientific | 2025 |
| Hobbs Potatoes Limited | Manufacturing | 2020 |
| Hockey Mentors CIC | Arts & recreation | 2021 |
| Holdideal Residents Management Limited | Households | 1988 |
| Holistic Health and Support Ltd | Health & social care | 2012 |
| Holland Hospitality ELY Ltd | Hospitality | 2026 |
| Holloseal Ltd | Manufacturing | 2009 |
| Holly Cottage LLP | | 2005 |
| Holly Lodge Anerley Limited | Construction | 2016 |
| Holmes Architecture & Planning Ltd | Professional & scientific | 2024 |
| Holmes-Darby Consultancy Limited | Professional & scientific | 2018 |
| Home Clean Home Ltd | Administrative & support | 2024 |
| Home Stretch Technology Limited | Information & communication | 2025 |
| Homedelivery-S&R Ltd | Wholesale & retail | 2025 |
| Homestay Consultancy Ltd | Administrative & support | 2009 |
| Homg UN Limited | Agriculture & fishing | 2025 |
| Honey POT Apps Limited | Information & communication | 2025 |
| Horizen Solutions Limited | Professional & scientific | 2014 |
| Horizon Retail Marketing Solutions Limited | Professional & scientific | 2009 |
| Hornets Rowing Club Limited | Arts & recreation | 2024 |
| Horsley Hale Farm Limited | Hospitality | 2017 |
| Host Family Consultancy Ltd | Administrative & support | 2011 |
| Housden's Caterers Ltd | Hospitality | 2011 |
| House of Heritage Limited | Wholesale & retail | 2016 |
| House of Wallensis Limited | Agriculture & fishing | 2017 |
| Howdale Management Company Limited | Households | 2004 |
| Hudson Laundry Services Limited | Other services | 2013 |
| Hughes Heart Imaging Ltd | Administrative & support | 2016 |
| Huntingdon Scaffolding Services Ltd | Construction | 2019 |
| Hurley Fitness Limited | Arts & recreation | 2018 |
| Hustronics Ltd | Professional & scientific | 2016 |
| Huxton Ltd | Information & communication | 2026 |
| Hyaku 100 Ltd | Hospitality | 2011 |
| Hydraco Group Limited | Financial services | 2004 |
| Hydrastar Limited | Extraterritorial | 2011 |
| Hylam Limited | Extraterritorial | 2013 |
| Hyland Drive Limited | Transport & logistics | 2008 |
| Hypha Ltd | Manufacturing | 2025 |
| I Biopharma Consultants Limited | Professional & scientific | 2011 |
| IAN Button Cars Limited | Wholesale & retail | 2002 |
| IAN Smith Kitchens and Bathrooms Limited | Construction | 2015 |
| Iansyst Limited | Information & communication | 1983 |
| Ibass Media Ltd | Information & communication | 2011 |
| Iceni Rise Management Company Limited | Households | 2019 |
| Icon Conveyor Belting Ltd | Manufacturing | 2025 |
| ID Mortgages Limited | Financial services | 2017 |
| Idealer Limited | Arts & recreation | 2006 |
| Idiversity Consulting Limited | Information & communication | 2019 |
| Ignis Salus Ltd | Professional & scientific | 2025 |
| Iksan Barbers Ltd | Other services | 2025 |
| Imajio Limited | Arts & recreation | 2007 |
| Imco Professional Services Limited | Professional & scientific | 2025 |
| Imlearningmandarin Ltd | Education | 2024 |
| Independence Limited | Wholesale & retail | 1999 |
| Indian Food (ELY) Ltd | Hospitality | 2023 |
| Indigo Clinical Consulting Ltd | Professional & scientific | 2022 |
| Indigo Transmit Films Ltd | Information & communication | 2017 |
| Inertiasoft Limited | Information & communication | 2004 |
| Inglis Professional Services Ltd | Professional & scientific | 2025 |
| Inika Publishing Services Limited | Information & communication | 2011 |
| INK Pulse Tech Ltd | Professional & scientific | 2020 |
| INK Rock Inc Limited | Other services | 2013 |
| Inner Order Limited | Administrative & support | 2024 |
| Innomech Limited | Other services | 1995 |
| Innovation Epicentre Limited | Administrative & support | 2019 |
| Insect Research & Development Limited | Professional & scientific | 2002 |
| Inside I.T. Limited | Information & communication | 1997 |
| Insight Home Surveys Limited | Administrative & support | 2004 |
| Insight Management Services (Global) Ltd | Administrative & support | 2011 |
| Insignia Media Ltd | Professional & scientific | 2025 |
| Instantpot Limited | Extraterritorial | 2014 |
| Integ Developments Limited | Construction | 2024 |
| Integral Part Ltd | Information & communication | 2017 |
| Integriq Ltd | Professional & scientific | 2024 |
| Interactive Business Dynamics Ltd | Administrative & support | 2013 |
| Interbirch Heights Consultants Group Ltd | Information & communication | 2020 |
| International Digital Marketing Agency (Idma) Ltd | Information & communication | 2026 |
| Internet With Integrity Limited | Wholesale & retail | 2009 |
| Interrogo Limited | Professional & scientific | 2013 |
| Iplan PPS Ltd | Professional & scientific | 2013 |
| Ipnetserve Limited | Extraterritorial | 2025 |
| Iprint Global Ltd | Information & communication | 2016 |
| IQ Signum Limited | Information & communication | 2024 |
| Iqra EL Tourky Limited | Health & social care | 2024 |
| Irvine Knight ICT Solutions Ltd | Information & communication | 2012 |
| IS Communications Limited | Information & communication | 1999 |
| IS Online Limited | Information & communication | 1996 |
| Isle Consulting Ltd | Professional & scientific | 2024 |
| Isleham Agricultural Contractors Limited | Administrative & support | 2007 |
| Isleham Carrot Growers Limited | Agriculture & fishing | 1990 |
| Isleham Community Association Limited | Arts & recreation | 2012 |
| Isleham Community Enterprises Limited | Arts & recreation | 2013 |
| Isleham FEN Limited | Hospitality | 2011 |
| Isolex Consulting Limited | Information & communication | 2021 |
| Ison Distribution Limited | Wholesale & retail | 1998 |