| Innovate Automation Limited | Wholesale & retail | 2023 |
| Innovation Support Services Ltd | Professional & scientific | 2014 |
| Innovative Robotic Intelligent Structures Ltd | Administrative & support | 2024 |
| Insanity Bars Ltd | Wholesale & retail | 2020 |
| Insit Moulded Packaging Limited | Manufacturing | 1987 |
| Instantina Holdings Limited | Financial services | 2025 |
| Intack Balti Ltd | Hospitality | 2026 |
| Intack Removals Limited | Transport & logistics | 2003 |
| Intack Tyres Limited | Wholesale & retail | 2025 |
| Intact Services Private Ltd | Transport & logistics | 2021 |
| Integra Community Living Options Limited | Health & social care | 2004 |
| Intelsource Ltd | Information & communication | 2026 |
| Inter Pro FC Ltd | Arts & recreation | 2023 |
| Inter-Stellar International Limited | Financial services | 2019 |
| International Assets Ltd | Extraterritorial | 2013 |
| International Music Event Production Ltd | Manufacturing | 2016 |
| Invertech Solutions Limited | Manufacturing | 2007 |
| Ioio Capital Ltd | Hospitality | 2021 |
| Ips-Uk Ltd | Manufacturing | 2009 |
| Irevtek Ltd | Professional & scientific | 2025 |
| Irongate Engineering Ltd | Professional & scientific | 2025 |
| Islamic-Explorers Ltd | Education | 2025 |
| Isothane Limited | Manufacturing | 1994 |
| Itouch Asset Finance Ltd | Information & communication | 2010 |
| Itouch Hire Ltd | Information & communication | 2010 |
| Itouch Live Ltd | Information & communication | 2013 |
| Itouch Pipeline Systems Ltd | Information & communication | 2010 |
| Itouch Reporting Systems Ltd | Manufacturing | 2013 |
| Itouch System Hire Ltd | Manufacturing | 2013 |
| Itouch Systems Ltd | Manufacturing | 2013 |
| IV Consultancy Ltd | Professional & scientific | 2022 |
| IV Creator Network Limited | Information & communication | 2025 |
| Izahah Ltd | Wholesale & retail | 2022 |
| J Clapperton Couriers Ltd | Transport & logistics | 2025 |
| J D R Construction & Groundworks Ltd | Construction | 2019 |
| J Lang Trading Limited | Real estate | 2025 |
| J P & Sons (Metal Recycling) Limited | Wholesale & retail | 2022 |
| J T Livesey (Accrington) Limited | Construction | 2003 |
| J&A UK Developments Ltd | Real estate | 2017 |
| J&C Supplies Ltd | Wholesale & retail | 2023 |
| J&H Accounting Limited | Administrative & support | 2022 |
| J. and T.J. Hindle Limited | Water & waste | 2010 |
| J. West and Sons (Carpets) Limited | Wholesale & retail | 2002 |
| J.H.D Properties Limited | Real estate | 2014 |
| J.L.A Roofing&Buildingspecialists Ltd | Construction | 2024 |
| J.Pollad Ltd | Wholesale & retail | 2023 |
| J.W.Tasker & SON Limited | Wholesale & retail | 1933 |
| J3 Construction Limited | Construction | 2019 |
| JA Pharmaceuticals Ltd | Health & social care | 2023 |
| Jabb Employment Support Ltd | Information & communication | 2022 |
| Jabran Khan Services Ltd | Health & social care | 2021 |
| Jacessi Limited | Professional & scientific | 2012 |
| Jack & Jacob Limited | Real estate | 2020 |
| Jack Nobbs & SON Limited | Transport & logistics | 2003 |
| Jack Nobbs (Holdings) Limited | Transport & logistics | 2003 |
| Jacket Junction Ltd | Wholesale & retail | 2025 |
| Jackson Taylor Law Ltd | Professional & scientific | 2024 |
| Jade Equity Limited | Financial services | 2008 |
| JAF Hardware Ltd | Construction | 2026 |
| Jaffa Accrington Limited | Hospitality | 2025 |
| Jaffa Limited | Hospitality | 2025 |
| Jake Alexander Hair and Body Sanctuary Ltd | Other services | 2025 |
| JAL Trading Ltd | Wholesale & retail | 2019 |
| James Dennett Plumbing and Heating Ltd | Construction | 2015 |
| James Dewhurst Limited | Manufacturing | 1952 |
| Jameson's Residential Home Limited | Administrative & support | 2005 |
| Jamrox Ltd | Hospitality | 2024 |
| JAN Silver House Ltd | Manufacturing | 2024 |
| Jane Waterfield Ltd | Professional & scientific | 2010 |
| Jason’S ROOFING1 Ltd | Construction | 2023 |
| JB Photography Ltd | Professional & scientific | 2022 |
| JBM Groundworks Ltd | Construction | 2020 |
| JBS Holiday Escapes Ltd | Hospitality | 2023 |
| JD Investments & Developments Ltd | Real estate | 2026 |
| JDL Double Glazing Limited | Manufacturing | 2006 |
| JDM Factory Ltd | Wholesale & retail | 2026 |
| Jenson's Funeral Directors Ltd | Other services | 2023 |
| Jfdistribution Limited | Wholesale & retail | 2025 |
| JH Multimarket Ltd | Wholesale & retail | 2024 |
| JI Motors Ltd | Wholesale & retail | 2025 |
| Jigsaw Advertising Ltd | Professional & scientific | 2025 |
| Jigsaw Children's Homes Ltd | Health & social care | 2024 |
| JIM Livesey & Associates Limited | Professional & scientific | 2006 |
| Jimmy & SON Ltd | Hospitality | 2022 |
| Jimmy's Garage NW Ltd | Wholesale & retail | 2021 |
| JIP Bemka Ltd | Wholesale & retail | 2024 |
| JJ Damp Proofing Ltd | Construction | 2026 |
| JJ Investment Holdings Group Limited | Real estate | 2024 |
| Jjnj Limited | Financial services | 2025 |
| JK Hybrid Parts Ltd | Wholesale & retail | 2022 |
| Jkbj Properties Ltd | Real estate | 2026 |
| JL Joinery and Building Ltd | Construction | 2025 |
| JLR Aviation Ltd | Manufacturing | 2026 |
| JLW Property Limited | Real estate | 2016 |
| JM Exterior Designs Ltd | Construction | 2025 |
| JMC Customz Ltd | Wholesale & retail | 2018 |
| JME Apparel Ltd | Wholesale & retail | 2025 |
| JMR Properties NW Ltd | Real estate | 2025 |
| Joanna Parcels Ltd | Transport & logistics | 2026 |
| Joel Tetlow Ltd | Financial services | 2025 |