| Ipplepen Garage Ltd | Wholesale & retail | 2023 |
| Ireland House Management Company Ltd | Real estate | 2021 |
| Iris Blue Limited | Professional & scientific | 2004 |
| Iron Van Innovations Ltd | Wholesale & retail | 2023 |
| Irvine Nott LLP | | 2009 |
| Isabel Properties Ltd | Real estate | 2019 |
| Isca Legal Solutions South West Limited | Professional & scientific | 2008 |
| Isca Trading Ltd | Wholesale & retail | 2015 |
| Isfri Limited | Wholesale & retail | 2024 |
| Isherwood Property Solutions Ltd | Administrative & support | 2024 |
| Isla Middleton Design Limited | Professional & scientific | 2021 |
| Island Waste Logistics Limited | Extraterritorial | 2019 |
| Isrm Limited | Other services | 2009 |
| Istanbul Barbers (SW) Ltd | Other services | 2022 |
| Isted Networks Ltd | Administrative & support | 2025 |
| IT Diversity Ltd | Information & communication | 2023 |
| Italian Food Heroes Ltd | Hospitality | 2015 |
| Italywithrelish Limited | Hospitality | 2009 |
| ITB Studio Limited | Construction | 2018 |
| Itracking Ltd | Administrative & support | 2008 |
| Itus Event Support Services Ltd | Administrative & support | 2015 |
| Iungo Limited | Information & communication | 2014 |
| IVY Property Solutions Limited | Real estate | 2021 |
| IWD Leasing Limited | Transport & logistics | 2003 |
| J & P Construction SW Ltd | Construction | 2020 |
| J & W Holdings Limited | Financial services | 2017 |
| J + P Trading Limited | Hospitality | 2001 |
| J a Short Plumbing and Heating Ltd | Construction | 2026 |
| J Broomes Consultancy Ltd | Professional & scientific | 2021 |
| J C Heatcare Ltd | Construction | 2010 |
| J D Forestry & Land Management Ltd | Agriculture & fishing | 2022 |
| J D T Property and Construction Limited | Professional & scientific | 2018 |
| J G Windows & Cladding Ltd | Construction | 2012 |
| J Hawkins Instructional Software Design Limited | Information & communication | 2011 |
| J L Roofing Solutions Limited | Construction | 2016 |
| J L Winter Limited | Real estate | 2026 |
| J P Hersey Ltd | Information & communication | 2013 |
| J P Wood Holdings Ltd | Financial services | 2022 |
| J Staunton Flues & Chimneys Limited | Extraterritorial | 2020 |
| J Wignall Limited | Real estate | 2009 |
| J&L Engineering Group Ltd | Financial services | 2026 |
| J,P&H Ltd | Other services | 2020 |
| J. E. S. E. Ltd | Manufacturing | 2006 |
| J.M. Strong General Builders Holdings Limited | Financial services | 2019 |
| J.M. Strong General Builders Limited | Construction | 2003 |
| J.R.S K9 Security Ltd | Financial services | 2022 |
| J.S.D. Investing Ltd | Information & communication | 2022 |
| J9M5 Caravans Limited | Water & waste | 2010 |
| J9M5 Limited | Wholesale & retail | 2010 |
| JA Rundle Estates Ltd | Real estate | 2024 |
| Jacana Energy Limited | Financial services | 2021 |
| Jacks Motor Works MOT Limited | Wholesale & retail | 2024 |
| Jackson Mitchell Limited | Professional & scientific | 2010 |
| Jacob's Island (Providence Square Blocks a, B & C) Limited | Real estate | 2001 |
| Jacob's Island (Providence Tower) Limited | Real estate | 2001 |
| Jaded Palates Stores Ltd. | Wholesale & retail | 2015 |
| Jagiha Limited | Professional & scientific | 2024 |
| Jaity Ltd | Professional & scientific | 2016 |
| Jakpot Limited | Extraterritorial | 2024 |
| James Family Holdings Ltd | Real estate | 2022 |
| James Family Partnership LLP | | 2023 |
| James Pinfold Farrier Limited | Other services | 2014 |
| James Reynolds Consulting Ltd | Professional & scientific | 2010 |
| James Taylor Bespoke Estate Agent Ltd | Real estate | 2021 |
| Jane Nelson Public Relations Limited | Information & communication | 2014 |
| Jasfer Limited | Wholesale & retail | 2020 |
| Jason Hancock Decking Limited | Construction | 2014 |
| Jason KEW Ltd | Professional & scientific | 2021 |
| Jason Miller Groundworks Limited | Administrative & support | 2017 |
| Jaspers Gift Shop Widecombe Ltd | Wholesale & retail | 2024 |
| JAX Co Clothing Ltd | Extraterritorial | 2021 |
| Jays Autobodies Limited | Wholesale & retail | 2022 |
| JB Holdings SW Limited | Financial services | 2026 |
| JB Outdoor Education Limited | Education | 2025 |
| JBG Estate Planning Limited | Administrative & support | 2022 |
| JBG Financials Ltd | Wholesale & retail | 2016 |
| JC Fire and Security Devon Ltd | Administrative & support | 2024 |
| Jcpr Properties Ltd | Construction | 2021 |
| JCT Plumbing & Heating Limited | Administrative & support | 2017 |
| Jdc-Enterprises Limited | Other services | 2008 |
| JDH Allen Cleaning Ltd | Administrative & support | 2025 |
| Jeanes Holdings Ltd | Administrative & support | 2019 |
| Jeff Townsley Holdings Limited | Financial services | 1997 |
| Jeff Townsley Limited | Manufacturing | 1978 |
| Jeffery Holdings Limited | Financial services | 2025 |
| Jellygirl Ltd | Information & communication | 2024 |
| JEM Asset Management Limited | Construction | 2020 |
| Jenks & Co Carpentry and Building Services Limited | Construction | 2025 |
| Jenny Communications Ltd | Wholesale & retail | 2020 |
| Jeremy Bishop Haulage Limited | Transport & logistics | 2010 |
| Jeremy M Burgess Ltd | Wholesale & retail | 2017 |
| Jetbay Limited | Administrative & support | 2009 |
| Jettadrain Ltd | Water & waste | 2004 |
| JFD Trawlers Limited | Agriculture & fishing | 2007 |
| JFL Property Services Limited | Real estate | 2023 |
| JG Automotive Services Limited | Wholesale & retail | 2024 |
| JG Steer Ltd | Hospitality | 2022 |
| Jiggle Power Limited | Professional & scientific | 2023 |
| JJ Craske Limited | Manufacturing | 2026 |
| JJB Electrical & Security Ltd | Manufacturing | 2020 |