| James Minns Ltd | Transport & logistics | 2015 |
| James Street Chef Ltd | Hospitality | 2022 |
| James United Ltd | Transport & logistics | 2024 |
| Jamieson Consulting Ltd | Professional & scientific | 2011 |
| Jamie’S Ltd | Households | 2023 |
| Jane-Mike Ltd | Real estate | 2023 |
| Janfran Services Ltd | Construction | 2023 |
| Jark Property Solutions Ltd | Real estate | 2025 |
| Jarvis Contract Roofing Ltd | Construction | 2025 |
| Jarvis Roofing Limited | Construction | 2009 |
| Jasbec Limited | Hospitality | 2010 |
| Jason Butcher Consultancy Ltd | Professional & scientific | 2024 |
| Javik Laser Ltd | Manufacturing | 2015 |
| JAW 4226 Services Limited | Construction | 2017 |
| JAY Arthur Ltd | Real estate | 2026 |
| Jay-Craft Food Machinery Limited | Manufacturing | 2003 |
| Jaycraft Food Machinery (UK) Limited | Professional & scientific | 2017 |
| Jayne Smith Ltd | Administrative & support | 2022 |
| Jaytei Marketing Limited | Wholesale & retail | 2011 |
| JAZ Consultancy Limited | Professional & scientific | 2025 |
| Jaztex Limited | Construction | 2006 |
| JB Carpentry and Construction Limited | Construction | 2025 |
| JB Properties (Norfolk) Limited | Construction | 2009 |
| JBC Construction (Norfolk) Limited | Construction | 2012 |
| Jbhb Ltd | Real estate | 2025 |
| JBP Tourism Ltd | Hospitality | 2016 |
| JCT Commercials Ltd | Wholesale & retail | 2023 |
| JCT Prestige Cars Ltd | Wholesale & retail | 2021 |
| JD Carpentry and Joinery Limited | Manufacturing | 2025 |
| JD Ceilings Ltd | Construction | 2024 |
| JDA Rentals Ltd | Real estate | 2023 |
| JDC Consult Group Ltd | Professional & scientific | 2023 |
| JEM Mace Drive Maintenance Ltd | Extraterritorial | 2014 |
| Jemsrunk Limited | Real estate | 2019 |
| Jennings Caravan Site Limited | Hospitality | 1975 |
| Jenred Limited | Health & social care | 2016 |
| Jen’S Property Maintenance Ltd | Construction | 2020 |
| JEX Silt Pumping Limited | Construction | 2020 |
| Jfrinvesting Ltd | Financial services | 2026 |
| JH Horizon Consulting Ltd | Professional & scientific | 2025 |
| JHM Hare & Daughters (Farming) LLP | | 2023 |
| JIB Property Management Limited | Real estate | 2017 |
| Jigsaw Enterprises Limited | Administrative & support | 2024 |
| JK Anota Properties Ltd | Real estate | 2023 |
| JK Bhogal Properties Limited | Real estate | 2025 |
| JKN Engineering Limited | Manufacturing | 2017 |
| JLC Surveys Limited | Construction | 2013 |
| JLM Property Developments Ltd | Real estate | 2024 |
| JLM Services (Norfolk) Limited | Information & communication | 2025 |
| JLN Builders Ltd. | Construction | 2019 |
| JLN Properties (Norfolk) Ltd. | Construction | 2020 |
| JLP Collective Ltd | Wholesale & retail | 2025 |
| JM Automated Gates Ltd | Administrative & support | 2026 |
| JM Electrical Norfolk Limited | Construction | 2025 |
| JMO Construction Limited | Construction | 2020 |
| JMO Interiors Limited | Construction | 2009 |
| JMS Caravan Services Limited | Manufacturing | 2024 |
| JO Shire Memorial Trust | Health & social care | 2015 |
| Joba & Co Ltd | Hospitality | 2013 |
| Jobspot Limited | Administrative & support | 2019 |
| JOE Graver Motor Engineer Limited | Wholesale & retail | 2013 |
| John H Banwell Road Haulage Limited | Transport & logistics | 2019 |
| John Lake Shellfish Limited | Agriculture & fishing | 1994 |
| John Lemon Construction Limited | Construction | 2021 |
| John Setchell Design Limited | Professional & scientific | 2012 |
| John Shackcloth Ltd | Construction | 2018 |
| John Wright Livestock Haulier Limited | Transport & logistics | 2016 |
| Johnson's Ironwork Ltd | Manufacturing | 2006 |
| Johnsons Cladding and Coatings Ltd | Construction | 2021 |
| Jomar Properties Limited | Real estate | 1973 |
| Jonathan Stevens Sullivan Limited | Wholesale & retail | 2023 |
| Jones Automotive Downham Market Ltd | Wholesale & retail | 2021 |
| Jordan Fitness Limited | Other services | 2020 |
| Jordan Leisure Limited | Extraterritorial | 2010 |
| Jordan Leisure Systems Limited | Other services | 1996 |
| Joywellness Limited | Wholesale & retail | 2025 |
| JP Plastering and Decorating Ltd | Administrative & support | 2017 |
| JP Property Investments Limited | Real estate | 2012 |
| JP Resolute Consultancy Ltd | Professional & scientific | 2018 |
| JPG Bookkeeping & Accountancy Services Limited | Professional & scientific | 2023 |
| JPR Smith Limited | Construction | 2025 |
| JRS Property Services Ltd | Administrative & support | 2010 |
| JRY Technical Services Ltd | Professional & scientific | 2025 |
| JS Properties KL Ltd | Real estate | 2024 |
| JSD Home Services Ltd | Construction | 2021 |
| JSR Holdings Ltd | Real estate | 2020 |
| JST Building Services Ltd | Construction | 2019 |
| JT Tech Ltd | Information & communication | 2024 |
| JTC Health & Safety Services Ltd | Professional & scientific | 2014 |
| JTT Properties Limited | Real estate | 2019 |
| Julian Farley Legal Services Limited | Professional & scientific | 2019 |
| Just ADD Property Ltd | Real estate | 2022 |
| Just JIB Limited | Wholesale & retail | 2016 |
| Just MWA Limited | Financial services | 2003 |
| Just Simply Work Ltd | Administrative & support | 2013 |
| Just Smile Kings Lynn Ltd | Health & social care | 2022 |
| Just Smile KL Limited | Health & social care | 2021 |
| JUST4YOUFITNESS Ltd | Arts & recreation | 2020 |
| Jwatfa IP Ltd | Professional & scientific | 2025 |
| K & J'S Grill Ltd | Hospitality | 2026 |