| Intelligent Trading Academy Ltd | Education | 2017 |
| Interior Techniques Limited | Construction | 2009 |
| International Lens Co. Ltd | Administrative & support | 2000 |
| International Magic Shop Limited | Wholesale & retail | 2018 |
| IPM Brickwork Ltd | Construction | 2014 |
| Iris Care Limited | Health & social care | 2022 |
| Ironclad Engineering & Fabrication Ltd | Manufacturing | 2025 |
| Ironclaws Tech Ltd | Information & communication | 2012 |
| Ironfighters United Ltd | Manufacturing | 2022 |
| Ironstrike Limited | Professional & scientific | 2026 |
| Isdw Limited | Arts & recreation | 2019 |
| Island Carpets Ltd | Wholesale & retail | 2012 |
| Island Gym Limited | Arts & recreation | 2017 |
| Island Leisure Parks Limited | Arts & recreation | 2016 |
| Islanders Fish Restaurants and Take Away Limited | Hospitality | 1998 |
| Islanderzesx Ltd | Extraterritorial | 2021 |
| ISM Property Developments Limited | Real estate | 2009 |
| Isoliners Ltd. | Extraterritorial | 1998 |
| Italian Market Garden Limited | Hospitality | 2012 |
| ITB Esports Ltd | Arts & recreation | 2020 |
| Itch-Mo Ltd | Wholesale & retail | 2017 |
| Itec Learning Technologies Limited | Education | 2004 |
| IVY BLU Consultants Ltd | Construction | 2020 |
| J & L Holdings Limited | Real estate | 2005 |
| J a Domestic Ltd | Administrative & support | 2020 |
| J D MEE & Sons Contracting Limited | Administrative & support | 2012 |
| J D MEE & Sons Renewables Limited | Energy | 2012 |
| J Davies Contracts Ltd | Manufacturing | 2013 |
| J Merrison Properties Limited | Real estate | 2018 |
| J P Scaffolding Services Limited | Construction | 2025 |
| J S Craigie Limited | Professional & scientific | 2009 |
| J S Paris Limited | Wholesale & retail | 2020 |
| J Young Property Services Ltd | Real estate | 2024 |
| J&A Serv Ltd | Construction | 2024 |
| J&M Logistics Solutions Ltd | Administrative & support | 2026 |
| J. E. Blackholly Ltd | Construction | 2018 |
| J.Dullee Heating Ltd | Construction | 2016 |
| J.F.G. Scaffolding Contractors Limited | | 1988 |
| J.L.B. Electrical Services Limited | Other services | 2002 |
| Jack Johnson Financial Services Limited | Financial services | 2019 |
| Jackpot Leisure Limited | Arts & recreation | 2002 |
| Jakapp Ltd | Information & communication | 2015 |
| Jake Seward Design Ltd | Professional & scientific | 2026 |
| James & Shane Parkin LLP | | 2010 |
| James Bickmore Barbers Ltd | Other services | 2023 |
| James Bickmore Salons Ltd | Other services | 2023 |
| Jamie Constructions Ltd | Construction | 2025 |
| Jane Hastings Travel Ltd | Administrative & support | 2020 |
| Jane Makeup Ltd | Other services | 2017 |
| Jark Engineering Ltd | Manufacturing | 2015 |
| Jasmin's Beauty & Aesthetics Limited | Other services | 2019 |
| JAW Healthcare Ltd | Administrative & support | 2024 |
| JAX Business Group Ltd | Administrative & support | 2025 |
| Jaycore Limited | Wholesale & retail | 2022 |
| JBW Developments Limited | Construction | 1995 |
| JC Computer Tech Ltd | Other services | 2010 |
| JCL Building Solutions Limited | Construction | 2019 |
| Jclr Ltd | Real estate | 2023 |
| Jcoci Educational Foundation Ltd | Other services | 2016 |
| JD Support Limited | Hospitality | 2023 |
| JDB Consultancy Ltd | Professional & scientific | 2026 |
| Jefrith Properties Limited | Real estate | 2021 |
| Jellybean Tiger Limited | Professional & scientific | 2015 |
| JEP Property Investments Ltd | Households | 2018 |
| Jessica Wood Solutions Limited | Information & communication | 2019 |
| JG Design and Build Ltd | Construction | 2015 |
| JGS Family Butcher Ltd | Wholesale & retail | 2026 |
| JHL Property Services Limited | Construction | 2022 |
| JHL Scaffolding Ltd | Construction | 2017 |
| JJC Real Estate Ltd | Real estate | 2017 |
| JJK Retail Ltd | Wholesale & retail | 2022 |
| JJM Driving School Ltd | Real estate | 2019 |
| JJM Eenterprise Ltd | Real estate | 2023 |
| JLR 4X4 Canvey Island Ltd | Wholesale & retail | 2025 |
| JN Counselling Therapy Ltd | Health & social care | 2024 |
| JNB Carpentry Ltd | Manufacturing | 2026 |
| JOB and Knock Rail GB1 Firmin Enterprises Ltd | Construction | 2020 |
| Jodie Martin Ltd | Financial services | 2024 |
| John White Holdings Ltd | Other services | 2021 |
| Jollydays Supported Holidays Worldwide LLP | | 2011 |
| Jonesy Shoes Ltd | Wholesale & retail | 2023 |
| Jorix Limited | Wholesale & retail | 2025 |
| JPL Electrical Solutions Limited | Construction | 2023 |
| JSS Fire & Security Ltd | Administrative & support | 2023 |
| Juanlife Ltd | Other services | 2025 |
| July Rollings Limited | Administrative & support | 2014 |
| Jumbo Jogger Ltd | Extraterritorial | 2018 |
| Jungle Fight Gear Limited | Wholesale & retail | 2025 |
| Just Imagine Nurseries - Canvey Island Ltd | Health & social care | 2016 |
| JW Ice Cream Company Limited | Manufacturing | 2017 |
| Jwg-It Group Limited | Administrative & support | 2006 |
| JWR Construction Services Ltd | Construction | 2017 |
| K & M Acro Training Ltd | Arts & recreation | 2019 |
| K J Sprinklers Limited | Construction | 2019 |
| K S Statics Ltd | Transport & logistics | 2022 |
| K-Chun Limited | Real estate | 2025 |
| K.L.M.Ductwork Ltd | Manufacturing | 1994 |
| K.S & F.B Developments Ltd | Construction | 2025 |
| K.W. Jones & Sons (Rayleigh) Limited | Construction | 1983 |
| Kalahari Health Co Limited | Wholesale & retail | 2017 |