| Itrade Global Ltd | Financial services | 2021 |
| ITS Networks Limited | Information & communication | 2011 |
| Itservicemhcomputer&Automotive Ltd | Wholesale & retail | 2026 |
| Itus 2 Communications Limited | Professional & scientific | 2016 |
| IV Car Parts Development Ltd | Wholesale & retail | 2025 |
| Ivory Grange Properties Limited | Real estate | 2018 |
| Iwilldigital Ltd | Information & communication | 2025 |
| Izabela Cleaning Service Ltd | Administrative & support | 2022 |
| J & a Business Consulting Limited | Construction | 2014 |
| J & K Consultancy Services Limited | Construction | 2026 |
| J a R S Construction Limited | Administrative & support | 2013 |
| J and C Motors Limited | Wholesale & retail | 2025 |
| J Anderson Properties Limited | Administrative & support | 2021 |
| J BEX Lifting Ltd | Construction | 2016 |
| J D Autos (Corby) Limited | Wholesale & retail | 2014 |
| J D Industrial Developments Limited | Other services | 2010 |
| J E Jackson Ltd | Other services | 2012 |
| J J B Grab Hire Ltd | Water & waste | 2020 |
| J Langen Ltd | Administrative & support | 2016 |
| J Manning Ltd | Construction | 2019 |
| J Matthews & Sons Builders Limited | | 2014 |
| J Merrilees Financial Services Ltd | Financial services | 2022 |
| J Shawcross Ventures Ltd | Wholesale & retail | 2026 |
| J&A Cleaning Solutions Limited | Administrative & support | 2024 |
| J&D Family Investments Limited | Real estate | 2025 |
| J&K Building Contractors Ltd | Construction | 2022 |
| J&K Sandhu Homes Ltd | Real estate | 2023 |
| J&R Autocare Ltd | Wholesale & retail | 2025 |
| J&S Mcnally Heating Services Limited | Construction | 2006 |
| J&S Property and Builders Limited | Real estate | 2026 |
| J.A Construction and Groundworks Ltd | Construction | 2024 |
| J.A.Glazing Limited | Construction | 2025 |
| J.C.M. Stables Limited | Financial services | 2003 |
| J.D.B. Refurbishments Limited | Other services | 2012 |
| J.Hind & SON Limited | Agriculture & fishing | 1954 |
| J.K.Pre-Insulated Pipe & Welding Services Limited | Construction | 2016 |
| J.Z.N.H Consulting Ltd | Professional & scientific | 2019 |
| JA & S Investments Ltd | Real estate | 2021 |
| Jabac Limited | Real estate | 2022 |
| JAC PDR Limited | Wholesale & retail | 2016 |
| Jachol Ltd | Hospitality | 2025 |
| Jacinto & Pateman Ltd | Other services | 2025 |
| Jack Lane Ltd | Real estate | 2025 |
| Jack Restaurant Ltd | Hospitality | 2026 |
| Jack Tomalin Racing Ltd | Arts & recreation | 2022 |
| Jack Warwick Funeral Service Limited | Other services | 2015 |
| Jack Wild Consulting Limited | Financial services | 2014 |
| Jack Williams Lighting Ltd | Professional & scientific | 2023 |
| Jackomedia Limited | Professional & scientific | 2010 |
| Jackson Composite Repair Ltd | Manufacturing | 2017 |
| Jacksons Contracting Limited | Real estate | 2012 |
| Jacqueline LE Claire Estates Ltd | Real estate | 2026 |
| Jade Advocacy Ltd | Professional & scientific | 2024 |
| JADEMARIA1995 Ltd | Other services | 2019 |
| Jagl Electrical Ltd | Construction | 2024 |
| Jah-Son Limited | Transport & logistics | 2018 |
| Jajm Automotive Ltd | Professional & scientific | 2015 |
| Jakowe Ltd | Information & communication | 2022 |
| Jalwal Automotive Ltd | Wholesale & retail | 2021 |
| Jalwal Investments Ltd | Real estate | 2025 |
| Jambotrans Ltd | Transport & logistics | 2015 |
| James Broadbent Limited | Real estate | 1999 |
| James Fish Construction Services Ltd | Construction | 2023 |
| James Hvac Controls Limited | Construction | 2016 |
| James Lifestyle Limited | Arts & recreation | 2011 |
| James Whiting Independent Trading Ltd | Information & communication | 2023 |
| Jamie's Furniture Store Ltd | Wholesale & retail | 2026 |
| Jamie's Property Portfolio Limited | Real estate | 2024 |
| Jamie's Quality Butchers Limited | Wholesale & retail | 2019 |
| Jamigo Homes Limited | Construction | 2026 |
| Jamm Products Limited | Administrative & support | 2006 |
| Jane Windsor Appointments Limited | Transport & logistics | 2006 |
| Janine Sykes Limited | Administrative & support | 2023 |
| Janion Plant Limited | Administrative & support | 2017 |
| Japco Developments Limited | Construction | 2011 |
| Jardentome Limited | Professional & scientific | 1989 |
| Jarral Medicare Limited | Health & social care | 2018 |
| JAS Resi Ltd | Real estate | 2025 |
| Jasbrita UK Ltd | Wholesale & retail | 2024 |
| Jaseam Ltd | Real estate | 2026 |
| Jason Draper Flooring Ltd | Construction | 2020 |
| Jason Goodliffe Group Ltd | Financial services | 2025 |
| Jason Goodliffe Property Limited | Real estate | 2025 |
| Jatom Limited | Real estate | 2023 |
| Jaworski Limited | Administrative & support | 2024 |
| Jayanvi Limited | Wholesale & retail | 2023 |
| Jaynabi Limited | Wholesale & retail | 2024 |
| Jaynjayns Ltd | Wholesale & retail | 2026 |
| Jayric Investments Limited | Extraterritorial | 2023 |
| Jays &J Group Ltd | Wholesale & retail | 2022 |
| JB Commercial Properties Limited | Construction | 2006 |
| JB Kettering Limited | Real estate | 2021 |
| JB Visional Ltd | Information & communication | 2020 |
| Jbhc Project Consulting Limited | Professional & scientific | 2019 |
| JBM Trading Ltd | Wholesale & retail | 2023 |
| JBR Offshore Engineering Limited | Administrative & support | 2016 |
| JBS Roofing Limited | Construction | 2002 |
| JC Designs & Fabrication Ltd | Professional & scientific | 2015 |
| JC Landscapes & Aggregates Ltd | Administrative & support | 2023 |
| Jc&Al Properties Ltd | Real estate | 2024 |