| Hotham Property Limited | Real estate | 2010 |
| House 2 Home.Essex Ltd | Construction | 2025 |
| House Atreides Limited | Wholesale & retail | 1996 |
| House Flipper International Limited | Real estate | 2021 |
| House IS a Feeling. Ltd | Hospitality | 2024 |
| House of Bordeaux Ltd | Wholesale & retail | 2023 |
| House of Seal Health Care Ltd | Health & social care | 2023 |
| House of Seal Limited | Administrative & support | 2016 |
| Howards Property Ltd | Real estate | 2023 |
| Howards Services Ltd | Administrative & support | 2021 |
| HQ Construction Consultants Ltd | Construction | 2015 |
| HQ Group Holdings Limited | Financial services | 2023 |
| Hrdot Ltd | Administrative & support | 2025 |
| HRH Experiences Limited | Arts & recreation | 2009 |
| Hukkoh Ltd | Hospitality | 2025 |
| Hunter One International Ltd | Administrative & support | 2015 |
| Hunters Auto Repair Ltd | Professional & scientific | 2024 |
| Hurricane Construction Ltd | Construction | 2021 |
| HUS Enterprises Ltd | Construction | 2026 |
| Hutton Group Management Limited | Financial services | 1999 |
| Hutton Kitchens Ongar Limited | Wholesale & retail | 1998 |
| Hutton Meadow Management Company Limited | Households | 2020 |
| Huxley Advisory Limited | Professional & scientific | 2017 |
| HWH Limited | Professional & scientific | 2026 |
| Hyde Consulting Group Ltd | Professional & scientific | 2025 |
| Hyde Homes Limited | Real estate | 2019 |
| Hydrogen Publicity Limited | Professional & scientific | 2001 |
| Hydurage Limited | Health & social care | 2016 |
| HYE Consultancy Ltd | Professional & scientific | 2016 |
| Hylux Limited | Wholesale & retail | 2023 |
| Hyperion Estates Limited | Agriculture & fishing | 1998 |
| I & I Healthcare Ltd | Health & social care | 2017 |
| I D W & Associates Limited | Information & communication | 2013 |
| I Pave Essex Ltd | Administrative & support | 2012 |
| I-Move Lettings Limited | Households | 2011 |
| I.S. Transport Limited | Transport & logistics | 2004 |
| I.T Valley View Solutions Ltd | Information & communication | 2025 |
| IAN Brown (Contractors) Ltd | Construction | 2008 |
| Iberian Framing Ltd | Construction | 2025 |
| Ibiza White Witch Limited | Financial services | 2022 |
| IBM Duerden Ltd | Hospitality | 2019 |
| IC8 Ltd | Information & communication | 2023 |
| Icashcars London Ltd | Wholesale & retail | 2023 |
| ICG Invest Limited | Real estate | 2022 |
| Icompress Limited | Manufacturing | 2025 |
| Icon Equestrian Limited | Wholesale & retail | 2022 |
| Icon Maintenance Services Ltd | Construction | 2023 |
| Icon Multi Services Ltd | Construction | 2021 |
| ID Move Limited | Information & communication | 2018 |
| Idee Group Limited | Wholesale & retail | 2015 |
| Identilabel Limited | Manufacturing | 1999 |
| IDN Consulting Limited | Professional & scientific | 2010 |
| IDO Properties Limited | Real estate | 2026 |
| IDR Total Solutions Ltd | Administrative & support | 2019 |
| Idxtra Limited | Information & communication | 2002 |
| IFS Print Limited | Manufacturing | 2020 |
| IG Property Developments Ltd | Construction | 2020 |
| Iganga Industries Ltd | Financial services | 2026 |
| IIS Group Ltd | Construction | 2021 |
| Ikym Ltd | Transport & logistics | 2016 |
| Ilford Tots to Teens Childcare Services Ltd | Education | 2017 |
| ILH Financial Limited | Financial services | 2010 |
| Iljm Snowling Rail Limited | Construction | 2018 |
| Imagentus Limited | Professional & scientific | 2012 |
| Imola Consultancy Services Limited | Administrative & support | 2016 |
| Impact Accounting Ltd | Professional & scientific | 2014 |
| Imperial Bird of Prey Academy Ltd | Professional & scientific | 2011 |
| Imperial Fire Group Ltd | Public administration | 2026 |
| Impey Davies Limited | Real estate | 2023 |
| Imported Tyre Manufacturers' Association (the) | Other services | 1984 |
| Impressive Works Limited | Construction | 2015 |
| Improve Your Marketing Ltd | Administrative & support | 2017 |
| Impulse Books UK Ltd | Arts & recreation | 2013 |
| Inbizco Ltd. | Information & communication | 2003 |
| Indian Cuisine Essex Limited | Hospitality | 2016 |
| Indian Valley Essex Limited | Hospitality | 2023 |
| Indigo London Property Management Ltd | Construction | 2019 |
| Indigo Plumbing and Heating Services Ltd | Construction | 2017 |
| Inditu Air Services Limited | Manufacturing | 2010 |
| Indoorhockeyuk Ltd | Education | 2020 |
| Infinity Motorhomes and Leisure Ltd | Wholesale & retail | 2026 |
| Inflatabakes Ltd | Manufacturing | 2020 |
| Info-Power Limited | Information & communication | 1999 |
| Informative Limited | Information & communication | 2008 |
| Inn AID Ltd | Education | 2025 |
| Innerspace Contracts Limited | Construction | 2013 |
| Innovatech Innovative Technology Limited | Professional & scientific | 2011 |
| Inotec Emergency Lighting Ltd | Manufacturing | 2012 |
| Inotec Limited | Administrative & support | 2012 |
| Inow Ltd | Professional & scientific | 2017 |
| Inpressed DRY Cleaning Ltd | Other services | 2015 |
| INS Leak Detection Ltd | Construction | 2020 |
| INS Property Claims Limited | Construction | 2016 |
| INS Property Construction Limited | Construction | 2026 |
| Insight Marketing Pro Ltd | Information & communication | 2022 |
| Inspira Sounds Ltd | Wholesale & retail | 2022 |
| Inspire ME Travel Limited | Administrative & support | 2018 |
| Insurance Auction Services Limited | Extraterritorial | 2000 |
| Inta Management Ltd | Information & communication | 2022 |
| Integrated Clinical Solutions Ltd | Health & social care | 2021 |