| Intensive Driving U.K. Limited | Education | 2002 |
| Inter County Link Limited | Transport & logistics | 2009 |
| Inter Technologies Limited | Administrative & support | 1990 |
| Intercon Trans Limited | Wholesale & retail | 2023 |
| Interior Solutions London Ltd | Other services | 2014 |
| Interm IT (Essex) Ltd | Information & communication | 2005 |
| International Freezer Services Limited | Manufacturing | 2013 |
| International Solar Education Limited | Education | 2025 |
| International Technical Solutions Limited | Professional & scientific | 2019 |
| Invest PLYN1 Ltd | Transport & logistics | 2025 |
| IO Loki Ltd | Transport & logistics | 2023 |
| Ionlymot Ltd | Wholesale & retail | 2020 |
| Ionut Ciocan Limited | Transport & logistics | 2025 |
| Ionut Ciurus Ltd | Transport & logistics | 2021 |
| Ionut Transport Logistic Ltd | Transport & logistics | 2026 |
| Ionut' World Transports Ltd | Transport & logistics | 2021 |
| IQ Health and Fitness Ltd | Arts & recreation | 2014 |
| Iqunity Limited | Information & communication | 2006 |
| Iris Investments Group Limited | Financial services | 2018 |
| Iris Packaging Limited | Manufacturing | 2016 |
| Iroko Designs (North West) Ltd | Wholesale & retail | 2010 |
| Iron Bjorn Ltd | Manufacturing | 2022 |
| Ironcladding.Uk Limited | Manufacturing | 2009 |
| Ironcraft Services (GY) Limited | Manufacturing | 2024 |
| Irongate (Grimsby) Limited | Real estate | 1996 |
| Irsea Ltd | Construction | 2025 |
| Isecure Ltd | Administrative & support | 2012 |
| Ishfish Ltd | Administrative & support | 2018 |
| Island Cleaning Solutions (IOW) Ltd | Administrative & support | 2019 |
| Isoqm Limited | Professional & scientific | 2024 |
| Isothema Limited | Professional & scientific | 2025 |
| Issy-Oj Ltd | Wholesale & retail | 2021 |
| Istanbul Grill GY Ltd | Hospitality | 2024 |
| Istanbul Grimsby Limited | Hospitality | 2024 |
| Istanbul Restaurant Grimsby Ltd | Hospitality | 2023 |
| ISW Childrens Services Limited | Health & social care | 2025 |
| Ittria Services Limited | Professional & scientific | 2002 |
| Ivan ANGELOV15 Limited | Hospitality | 2025 |
| IVY Marine & Fabrication Services Ltd | Manufacturing | 2017 |
| Iygb Ltd | Health & social care | 2025 |
| Izi-Ht Services Limited | Transport & logistics | 2014 |
| J & F Scaffolding Services Ltd | Construction | 2022 |
| J & G Footman Ltd | Wholesale & retail | 2015 |
| J Bass Limited | Construction | 2020 |
| J C Cook Cycles Limited | Wholesale & retail | 2015 |
| J C Steel Engineering Services Limited | Professional & scientific | 2025 |
| J Chapman Joinery Limited | Construction | 2025 |
| J D Management Services (Kent) Limited | Other services | 2011 |
| J Durkin Limited | Manufacturing | 2019 |
| J F Prosthetics Limited | Health & social care | 2014 |
| J Francis Advisory Ltd | Professional & scientific | 2018 |
| J French Services Limited | Administrative & support | 2024 |
| J G L Properties Limited | Administrative & support | 1998 |
| J H Developments (GB) Limited | Real estate | 2010 |
| J H Todd & SON (Coal Merchants) Ltd | Wholesale & retail | 2002 |
| J Hancock Electrical Ltd | Construction | 2025 |
| J J Hynes Limited | Construction | 2010 |
| J J Noton Ltd | Professional & scientific | 2018 |
| J Joyce Engineering Ltd | Professional & scientific | 2025 |
| J M L (Keelby) Limited | Hospitality | 1999 |
| J Marchant Building Services Ltd | Construction | 2024 |
| J Melton Tree Surgery Limited | Agriculture & fishing | 2002 |
| J P Ashley Limited | Construction | 2003 |
| J P Rowe Electrical Ltd | Construction | 2018 |
| J R Downer Limited | Construction | 2014 |
| J Sharp Ltd | Wholesale & retail | 2016 |
| J Southern Plumbing & Heating Limited | Construction | 2026 |
| J T Property Group Ltd | Real estate | 2018 |
| J T Property Rentals Ltd | Real estate | 2020 |
| J Turgoose Building and Bricklaying Services Ltd | Construction | 2021 |
| J V Retail Design Limited | Professional & scientific | 2008 |
| J W Codd Ltd | Agriculture & fishing | 2024 |
| J W Plumbing and Joinery Ltd | Construction | 2026 |
| J White Consultants Ltd | Professional & scientific | 2022 |
| J&B Building Services Limited | Construction | 2019 |
| J&B Vehicle and Cycle Services Limited | Wholesale & retail | 2018 |
| J&C Trans Ltd | Transport & logistics | 2020 |
| J&J Birkett Developers Limited | Construction | 2016 |
| J&M Cooper Information Security Analysts Ltd | Administrative & support | 2016 |
| J&S Property & Landscape Solutions Ltd | Construction | 2020 |
| J&T Investment Property Ltd | Real estate | 2026 |
| J. & M. Land Co. (Humberside) Limited | Construction | 1979 |
| J. Birkett Joinery Limited | Construction | 2003 |
| J. K. Construction & Building Services Ltd | Construction | 2010 |
| J.A.C.K.S Developments Ltd | Construction | 2018 |
| J.A.C.K.S Maintenance Limited | Administrative & support | 2019 |
| J.A.G. Engineering Services Ltd | Professional & scientific | 2024 |
| J.B.A. (Fish Sales) Limited | Wholesale & retail | 1979 |
| J.C.S. Fish Limited | Manufacturing | 2000 |
| J.D. Mawby & Sons Limited | Agriculture & fishing | 1956 |
| J.G. Fisher Limited | Agriculture & fishing | 1955 |
| J.H. Bacon Limited | Agriculture & fishing | 1974 |
| J.Johnson Mechanical Limited | Construction | 2015 |
| J.L.D. Plumbing & Heating Limited | Construction | 2008 |
| J.L.S Freight Ltd | Transport & logistics | 2015 |
| J2 Plumbing and Heating Ltd | Construction | 2021 |
| J3 Build Ltd | Extraterritorial | 2023 |
| J3 Roofing Ltd | Construction | 2022 |
| Jace Property Ltd | Real estate | 2020 |
| Jack Sprats Limited | Wholesale & retail | 2021 |