| ISL Acquisitions Ltd | Administrative & support | 2018 |
| ISL Transport Ltd | Transport & logistics | 2020 |
| Island Essennce Ltd | Hospitality | 2025 |
| ISOLVE4 Ltd | Information & communication | 2024 |
| Issa Property Investments Limited | Real estate | 2024 |
| Ivan Allard Limited | Administrative & support | 2006 |
| Ivaniuc Metal Works Ltd | Manufacturing | 2021 |
| Ivaniuc Welding & Fabrications Ltd | Manufacturing | 2021 |
| Ivydene Property Investment Limited | Real estate | 2019 |
| J & D Taylor Ltd. | Wholesale & retail | 2007 |
| J & J Fishing Ltd | Agriculture & fishing | 2019 |
| J & L Recruitment Limited | Administrative & support | 2014 |
| J C Commissioning Limited | Construction | 2001 |
| J Davies Mortgage Services Limited | Financial services | 2021 |
| J Firman Trees and Fences Limited | Administrative & support | 2017 |
| J R Harbidge and Daughters Ltd | Real estate | 2021 |
| J Rose Roofing and Building Services Ltd | Construction | 2024 |
| J Samuel Interiors & Construction Limited | Construction | 2020 |
| J Stone Design & Construction Ltd | Construction | 2012 |
| J T Hunt Limited | Construction | 2019 |
| J Whitehall Contracting Ltd | Agriculture & fishing | 2026 |
| J&B Real Estate Investments Limited | Financial services | 2025 |
| J&J UK Sales Limited | Wholesale & retail | 2021 |
| J&R Ltd | Wholesale & retail | 2025 |
| J. E. Crooks Limited | Construction | 2005 |
| J. W. Diaper & Sons Limited | Financial services | 2008 |
| Jackaman Honor Ltd | Other services | 2019 |
| Jadeward Limited | Other services | 2016 |
| Jagdier Ltd | Construction | 2018 |
| Jakmol Ventures Limited | Professional & scientific | 2018 |
| Jamanji Ltd | Professional & scientific | 2006 |
| James Bryan Limited | Construction | 2008 |
| James Charles Consulting Limited | Professional & scientific | 2015 |
| James Charles Investments Limited | Financial services | 2021 |
| James George Property Limited | Real estate | 2022 |
| James Hardy Property Limited | Real estate | 2022 |
| Janine Mathó International Ltd | Professional & scientific | 2024 |
| Japar Ltd | Information & communication | 2026 |
| Jasons Classic Cars Limited | Wholesale & retail | 2024 |
| JCD Vehicle Solutions Ltd | Wholesale & retail | 2020 |
| JCP Financial Limited | Professional & scientific | 2015 |
| JCP Properties (EA) Limited | Real estate | 2023 |
| JD HR Consultancy Limited | Administrative & support | 2024 |
| JD Services Stowmarket Ltd | Water & waste | 2025 |
| JDG Experiences Limited | Professional & scientific | 2007 |
| Jebmotors Ltd | Wholesale & retail | 2024 |
| Jennifer Duffee Fitness Ltd | Other services | 2017 |
| Jess Cooks Limited | Manufacturing | 2019 |
| Jj's Property Improvements (Essex) Limited | Construction | 2024 |
| JLK Holdings Limited | Real estate | 2016 |
| JLM Consulting HR Limited | Professional & scientific | 2011 |
| JO Booth Associates Limited | Professional & scientific | 2018 |
| Jockeys Farm Partnership | | 1984 |
| JOE Piper Ltd | Construction | 2024 |
| Joel Whitlock Engineering Solutions Ltd | Construction | 2019 |
| John Peel Centre for Creative Arts CIC | Arts & recreation | 2010 |
| Johnson & Keeble Ltd | Construction | 2010 |
| Johnson Investments (Debenham) Ltd | Real estate | 2023 |
| Jolly Good Building & Renovation Limited | Construction | 2007 |
| Jonathan Penn and Company Trust Corporation Limited | Financial services | 2019 |
| Jonathan Penn Limited | Extraterritorial | 2023 |
| Jone Modern Garment Works Limited | Wholesale & retail | 2026 |
| Jordan Walker Ltd | Professional & scientific | 2019 |
| Joywood Limited | Real estate | 2024 |
| JPR Insurance Brokers Ltd | Financial services | 2003 |
| JRT Energy Limited | Professional & scientific | 2003 |
| Julie Paice Consulting Limited | Professional & scientific | 2011 |
| Jusdents Limited | Wholesale & retail | 2015 |
| Just Building Services Ltd | Construction | 2023 |
| Just Essentials Hair & Beauty Store (Ipswich) Ltd | Wholesale & retail | 2024 |
| Just-In-Case Pharma Limited | Health & social care | 2019 |
| JV Technology Transformation Ltd | Information & communication | 2022 |
| JW Property Investments Limited | Real estate | 2020 |
| K Muir Consulting Limited | Professional & scientific | 2026 |
| K Pizza Fresh Ltd | Hospitality | 2023 |
| K9-MATES UK | Agriculture & fishing | 2023 |
| K9GRILLZ UK Limited | Manufacturing | 2023 |
| K9SELECT Ltd | Manufacturing | 2019 |
| Kaelor Logistics Ltd. | Transport & logistics | 2024 |
| Kaelor Medical Ltd | Transport & logistics | 2025 |
| Kala JAM Ltd | Hospitality | 2024 |
| Kalo Civil Engineering Ltd | Construction | 2023 |
| Karen Fallon & Co Limited | Health & social care | 2010 |
| Karen Ross Limited | Information & communication | 2024 |
| KAT Property Investments Limited | Real estate | 2016 |
| Kate Pickering Consulting Limited | Professional & scientific | 2024 |
| Keeping the Beat Ltd | Other services | 2020 |
| Keko Ltd | Hospitality | 2025 |
| Kels George Limited | Professional & scientific | 2021 |
| KEN Gallienne & Associates Limited | Professional & scientific | 2015 |
| Kendrick Fits Ltd | Construction | 2022 |
| Kensington Road 1955 Limited | Extraterritorial | 2014 |
| Kerim Kebab Ltd | Hospitality | 2018 |
| Kevin Hollings Quality Kitchens Limited | Construction | 2013 |
| Keyflex Properties Ltd | Real estate | 2021 |
| Kezia Ltd | Wholesale & retail | 2026 |
| Kicks and Tricks Ltd | Education | 2022 |
| Kids' Food & Drink Collective Ltd | Manufacturing | 2024 |
| KIK Creative Ltd | Information & communication | 2025 |
| Killeen Logistics Ltd | Transport & logistics | 2025 |