| Household,Industrial and Technical Electrical Contractors Limited | Construction | 1988 |
| HS Talent Limited | Administrative & support | 2023 |
| Humid Mechanical Services Limited | Professional & scientific | 2016 |
| I. S. Clenaghan Services Limited | Other services | 2019 |
| Idle Hands Consultancy Ltd | Other services | 2025 |
| Imagination Creation Limited | Arts & recreation | 2018 |
| Imperial Heritage Ltd | Real estate | 2019 |
| Imperial Pipework Freezing Services Ltd | Construction | 2020 |
| Imperial Water Treatment & Commissioning Services Ltd | Construction | 2019 |
| IN the Wild Ltd. | Administrative & support | 2016 |
| IN2 Contracts Ltd | Construction | 2023 |
| Indian Samosa Ltd | Hospitality | 2025 |
| Inform Display Ltd | Manufacturing | 2003 |
| Infradev Ltd | Administrative & support | 2016 |
| Infrastructure Consultancy Limited | Information & communication | 2007 |
| Ingatestone Community Centre Parking Limited | Transport & logistics | 2026 |
| Ingatestone Motors Ltd | Wholesale & retail | 2020 |
| Ingatestone Nails Limited | Other services | 2026 |
| Ingatestone Saddlery Centre Limited | Wholesale & retail | 2006 |
| Inglis Mclenor Group 2024 Ltd | Financial services | 2024 |
| Inglis Mclenor Holdings 2023 Ltd | Financial services | 2023 |
| Inglis Mclenor Ltd | Professional & scientific | 1972 |
| Innovative Infill (18 HP) Ltd | Construction | 2023 |
| Innovative Infill Ltd | Construction | 2019 |
| Inqusiv Limited | Information & communication | 2023 |
| Inspiral Developments Limited | Professional & scientific | 1998 |
| INT3GRATE Ltd | Information & communication | 2016 |
| International Book Services (UK) Limited | Other services | 2009 |
| International Petroleum Products Limited | Wholesale & retail | 2002 |
| Involved IT Ltd | Information & communication | 2016 |
| IPE (Salamons Way) Ltd. | Water & waste | 2008 |
| IPE Bubbles Ltd | Construction | 2009 |
| IPE Thetford Ltd | Construction | 2009 |
| Iris Photonics Limited | Administrative & support | 2018 |
| Ironic Metals Limited | Professional & scientific | 2025 |
| Itsurgrlaisha Ltd | Information & communication | 2026 |
| J K Electrical Contractors Ltd | Administrative & support | 2015 |
| J Matthews Plant Hire Limited | Administrative & support | 1988 |
| J&H Energy Limited | Financial services | 2011 |
| J.A. Allen Ltd | Construction | 2010 |
| J.G Recruitment Limited | Administrative & support | 2014 |
| Jackson Birch MSA Ltd | Professional & scientific | 2023 |
| Jacobs Associates Property Ltd | Households | 2021 |
| James Duncan Workwear Ltd | Financial services | 2024 |
| Jason William Wickham Ltd | Extraterritorial | 2025 |
| JAY Group UK Ltd | Other services | 2018 |
| Jayne's House Holdings Ltd | Financial services | 2018 |
| JCL Donnelly Ltd | Financial services | 2021 |
| Jcpath Ltd | Health & social care | 2023 |
| JD Insight Limited | Professional & scientific | 2013 |
| Jega Developments Limited | Construction | 2016 |
| Jega Homes (110 High ST.) Ltd | Real estate | 2026 |
| Jega Homes (Stock Road) Holdings Limited | Financial services | 2025 |
| Jega Homes (Stock Road) Limited | Construction | 2025 |
| Jega Homes Ltd | Other services | 2020 |
| Jesters Childcare Beaulieu CIC | Health & social care | 2018 |
| Jesters Kids Clubs & Nursery School CIC | Health & social care | 2003 |
| Jesters Nursery Childcare Limited | Other services | 2017 |
| Jetcleanessex Ltd. | Administrative & support | 2025 |
| Jfrance & Co Ltd | Professional & scientific | 2026 |
| JKD Concepts Ltd | Financial services | 2022 |
| John Crouch Court Limited | Extraterritorial | 2003 |
| Johnson Builders Limited | Construction | 2005 |
| Joseph James Developments Ltd | Construction | 2003 |
| Josh Ortega Limited | Information & communication | 2021 |
| JP Systems Limited | Construction | 2017 |
| JRW Carpentry Limited | Construction | 2018 |
| JS Carpentry & Maintenance Ltd | Construction | 2023 |
| JTP KOI Ltd | Wholesale & retail | 2025 |
| Jubilee Projects Limited | Real estate | 1995 |
| Jujitsucise Ltd | Education | 2026 |
| JWH Investment Limited | Financial services | 2025 |
| JWS Aviation Ltd | Financial services | 2021 |
| K & a Contracting Limited | Agriculture & fishing | 2015 |
| K P Robinson Ltd | Professional & scientific | 2026 |
| K.G. Young Limited | Construction | 1981 |
| Kanjy Property Group Limited | Real estate | 2019 |
| KAY AY Solutions Limited | Professional & scientific | 2015 |
| Kell Mitchell Limited | Professional & scientific | 2017 |
| Kerwin Barn Conversions Limited | Construction | 2026 |
| KIN and Hope Ltd | Wholesale & retail | 2018 |
| Kingfishers (Ingatestone) Limited | Other services | 1972 |
| Kinkane Capital Ltd | Financial services | 2018 |
| Kirkdale Road Limited | Construction | 2015 |
| Kiss Building Co. Limited | Construction | 2001 |
| Kiss Homes Limited | Construction | 2001 |
| Kitchen Consultants Europe Ltd | Construction | 2021 |
| Kitchens From Design Limited | Wholesale & retail | 2011 |
| KLX Logistics Limited | Wholesale & retail | 2018 |
| Know Mobility Limited | Professional & scientific | 2019 |
| Knowles Services Ltd | Administrative & support | 2024 |
| Konvers London Limited | Construction | 2017 |
| Kozak Sich Limited | Information & communication | 2015 |
| Kudos Data Solutions Group Ltd | Information & communication | 2017 |
| Kynova Limited | Administrative & support | 2025 |
| L&L Evans Properties Ltd | Real estate | 2017 |
| L. Smith Contracts Limited | Construction | 2001 |
| L.G. Performance Limited | Professional & scientific | 2013 |
| LA Global Ltd | Arts & recreation | 2019 |
| LA Piazza Investments Ltd | Real estate | 2022 |