| Iloyalty Limited | Professional & scientific | 2010 |
| Immelsk Ltd | Manufacturing | 2020 |
| Impact Car Storage Limited | Transport & logistics | 2017 |
| Impact Change Limited | Professional & scientific | 2020 |
| Imperium Food Ingredients Ltd | Manufacturing | 2025 |
| Imprest-Uk Limited | Other services | 2015 |
| Imprint Creative Print Solutions Limited | Manufacturing | 2002 |
| IN Service Lifts Limited | Professional & scientific | 2025 |
| IN Time Connection Ltd | Professional & scientific | 2017 |
| Inbound Call Solutions Limited | Information & communication | 2011 |
| Indiga Limited | Administrative & support | 2002 |
| Indiki Club Limited | Wholesale & retail | 2024 |
| Indiki Limited | Manufacturing | 2019 |
| Indreco Ltd | Administrative & support | 2022 |
| Infinitepaving Limited | Administrative & support | 2005 |
| Infinity Stone Limited | Mining & quarrying | 2012 |
| Infytrend Ltd | Transport & logistics | 2018 |
| Inkluminati Tattoo Ltd | Other services | 2024 |
| Innfusion Leisure Limited | Hospitality | 2006 |
| Innocon Ltd | Professional & scientific | 2018 |
| Inside Outbuildings Ltd | Construction | 2021 |
| Instant-Connect Limited | Information & communication | 2024 |
| Integrum AI Group Ltd | Hospitality | 2025 |
| Intemp Furnace Support Ltd | Manufacturing | 2022 |
| Intercomp Europe Limited | Wholesale & retail | 2001 |
| International Animal Rescue | Professional & scientific | 2006 |
| International Animal Rescue Trading Limited | Wholesale & retail | 1992 |
| International Christian Communications | Information & communication | 2000 |
| Invest Britain Ltd | Real estate | 2020 |
| Invest-R Ltd | Information & communication | 2013 |
| Involute Ltd | Professional & scientific | 2006 |
| Ipec Engineering Consultants Limited | Information & communication | 2017 |
| Isenhurst Court (Heathfield) Freehold Ltd | Real estate | 2013 |
| Isfield Miniature Railway Ltd. | Transport & logistics | 2024 |
| IT IS What IT IS Ltd | Wholesale & retail | 2025 |
| Itedomum (UK) Ltd | Wholesale & retail | 2015 |
| Iterior Limited | Manufacturing | 2005 |
| IX Networks Ltd | Information & communication | 2015 |
| J & C Spink Associates Limited | Real estate | 2018 |
| J Billings Groundwork Ltd | Construction | 2009 |
| J Delves Subcontract Services Limited | Administrative & support | 2014 |
| J G Leadwork & Roofing Limited | Administrative & support | 2021 |
| J Goldsmith Ltd | Administrative & support | 2012 |
| J W Kininmonth & Co. Ltd. | Financial services | 2014 |
| J Woollard and Sons Ltd | Manufacturing | 2026 |
| J2 Sourcing Limited | Administrative & support | 2019 |
| Jacgora Investments Limited | Administrative & support | 2003 |
| Jadrad Holdings Limited | Real estate | 2017 |
| JAE Investments Ltd | Financial services | 2025 |
| JAM Start Ltd | Administrative & support | 2014 |
| Jamis Ltd | Hospitality | 2009 |
| Jascar Services Ltd | Information & communication | 2019 |
| JAX and Ralph Ltd | Hospitality | 2010 |
| JCK Trading Ltd | Wholesale & retail | 2025 |
| Jeepers Squeakers Ltd | Wholesale & retail | 2024 |
| Jeffanoos Limited | Financial services | 2020 |
| Jemtech (UK) Limited | Wholesale & retail | 1996 |
| Jenny Hudson Consultancy Limited | Other services | 2014 |
| Jepolini Ltd | Arts & recreation | 2023 |
| Jesvano Value Mart Limited | Wholesale & retail | 2024 |
| JFR Consultancy Limited | Professional & scientific | 2025 |
| JG Construction Ltd | Construction | 2025 |
| JK4 Ltd | Construction | 2025 |
| Jlbfm Corp Ltd | Real estate | 2025 |
| JM Drive Ltd | Education | 2020 |
| JMJ Care'N'Cure Limited | Health & social care | 2018 |
| JMN Oak Properties Limited | Real estate | 2018 |
| JO Argent Consultancy Services Limited | Professional & scientific | 2010 |
| JO Natural Ltd | Other services | 2018 |
| Joinery Boys Limited | Manufacturing | 2018 |
| Jolu Developments Ltd | Real estate | 2021 |
| Josefinaonline Limited | Wholesale & retail | 2020 |
| JRB Gaming Ltd | Wholesale & retail | 2026 |
| Jrlomas Tech Limited | Information & communication | 2019 |
| JS Holding Europe Ltd | Financial services | 2023 |
| JSB Uckfield Ltd | Hospitality | 2022 |
| Jungle Agency Limited | Professional & scientific | 2022 |
| Just in Case Cyber Security Ltd | Information & communication | 2019 |
| Just Mots Uckfield Limited | Wholesale & retail | 2013 |
| Just Simply Organised Limited | Professional & scientific | 2003 |
| K & B News Ltd | Wholesale & retail | 2021 |
| K & K News Ltd | Wholesale & retail | 2017 |
| K&K Football Consultancy Ltd | Health & social care | 2023 |
| K&M Team Consulting Ltd | Administrative & support | 2022 |
| Kalmax Investments Limited | Real estate | 2016 |
| Kalmax Limited | Extraterritorial | 1955 |
| Kalmax Properties Limited | Real estate | 2012 |
| Kam's Fish Bar Ltd | Hospitality | 2023 |
| Kam's Property Flip Ltd | Real estate | 2025 |
| Kamlax Limited | Real estate | 2015 |
| Kanbina Ltd | Information & communication | 2019 |
| Karenstephens Ltd | Professional & scientific | 2023 |
| Kbnc Limited | Administrative & support | 2008 |
| Kdevi Ltd | Wholesale & retail | 2024 |
| KDI Autocare Ltd | Wholesale & retail | 2025 |
| KDW Trustees Ltd | Financial services | 2019 |
| Keable & Todhunter Limited | Real estate | 2022 |
| Kearsley Equine Services Ltd | Agriculture & fishing | 2024 |
| Kemp Town Tennis Club Limited | Arts & recreation | 1998 |
| Kensal Editing Ltd | Information & communication | 2015 |