| Instauro Ltd | Professional & scientific | 2016 |
| Insurelink Limited | Financial services | 1995 |
| Integrated Marketing Consultants Ltd | Information & communication | 2018 |
| International Budo Federation (UK) Limited | Education | 2025 |
| Internet Affiliation Ltd | Professional & scientific | 2010 |
| Interpac Norwich Limited | Administrative & support | 2025 |
| Involve Active Ltd | Education | 2012 |
| Ionut Trans RD Ltd | Transport & logistics | 2026 |
| Isabelle's Nail Haven Ltd | Other services | 2025 |
| Isis Advisory Services Limited | Professional & scientific | 2012 |
| It's a Dog's Life Ltd | Other services | 2014 |
| Itog Services Limited | Mining & quarrying | 2025 |
| Itsystemsolutions Limited | Information & communication | 2016 |
| IVY Health Surgery Limited | Health & social care | 2017 |
| IVY House Country Hotel Ltd | Hospitality | 2013 |
| J & F Foods Ltd | Hospitality | 2019 |
| J & S Creations Ltd | Manufacturing | 2018 |
| J and D Design Solutions Ltd | Professional & scientific | 2024 |
| J C Luxury Sportswear Limited | Professional & scientific | 2021 |
| J C Marjoram Limited | Professional & scientific | 2019 |
| J D Automotive & Recovery Ltd | Wholesale & retail | 2020 |
| J Diamond Limited | Health & social care | 2017 |
| J Elmy Construction Ltd | Construction | 2020 |
| J L Building Services Ltd | Construction | 2025 |
| J M Fibreglass Limited | Manufacturing | 2016 |
| J O Roofing Limited | Construction | 2020 |
| J S Hughes Developments Limited | Construction | 2021 |
| J Tucker Engineering Limited | Professional & scientific | 2015 |
| J Wilson Lettings Ltd | Real estate | 2026 |
| J&N Coffee Corner Ltd | Wholesale & retail | 2024 |
| J&S Scaffolding Ltd | Construction | 2022 |
| J.C.J.B Ltd | Hospitality | 2025 |
| J.D. Engineering (EA) Ltd | Professional & scientific | 2022 |
| J.D.Batson Carpentry Limited | Construction | 2018 |
| J.G.K. Leisure Limited | Hospitality | 2009 |
| J.J Unified Ltd | Wholesale & retail | 2024 |
| J.J.T.N Ltd | Wholesale & retail | 2017 |
| J.N. Bedrooms Limited | Wholesale & retail | 2012 |
| Jaccontracting Ltd | Professional & scientific | 2024 |
| Jack Robert Lettings Limited | Real estate | 2022 |
| Jackos CAB Ltd | Transport & logistics | 2023 |
| Jackson Marine Limited | Wholesale & retail | 2017 |
| Jacob Lifting Limited | Manufacturing | 2025 |
| Jadecarbon Limited | Professional & scientific | 2023 |
| Jaffa Imports Limited | Wholesale & retail | 2009 |
| Jaffer Investments Limited | Hospitality | 1999 |
| James Finance Limited | Administrative & support | 2022 |
| James Hartwell Services Limited | Professional & scientific | 2009 |
| James JAY Global Limited | Construction | 2009 |
| James Leech Lighting Ltd | Information & communication | 2022 |
| James Macdonald Fitness Ltd | Health & social care | 2023 |
| Jaohar UK Limited | Administrative & support | 2006 |
| Jaracs Limited | Professional & scientific | 2010 |
| Jason Bodmer Environmental Solutions Limited | Professional & scientific | 2014 |
| Jaws High Voltage Solutions Limited | Mining & quarrying | 2024 |
| JAY2GRAY Enterprises Ltd | Construction | 2013 |
| Jaylocks Limited | Professional & scientific | 2025 |
| JB Resources (EA) Ltd | Professional & scientific | 2023 |
| JB Taverns Ltd | Hospitality | 2016 |
| JBL Weld Limited | Construction | 2013 |
| Jcmarine Ltd | Agriculture & fishing | 2026 |
| JCS Plumbing & Heating Services Limited | Construction | 2024 |
| JD Clayton Ltd | Construction | 2018 |
| JD Fibre Network Planning Ltd | Information & communication | 2025 |
| Jdk-Comercials Ltd | Wholesale & retail | 2024 |
| Jdwinney Capital Ltd | Financial services | 2026 |
| Jerry Keeble Photography Ltd | Professional & scientific | 2023 |
| JET Adventures Limited | Arts & recreation | 2020 |
| JFS Technologies Ltd | Information & communication | 2017 |
| JGN Property Investors Ltd | Real estate | 2023 |
| JIB Great Yarmouth Limited | Mining & quarrying | 2023 |
| Jigshaw Renovation Ltd | Construction | 2023 |
| Jimtek Ltd | Mining & quarrying | 2012 |
| JIS Electrical Limited | Construction | 2025 |
| JJ COX Ltd | Transport & logistics | 2026 |
| Jj's Services (East Anglia) Ltd | Construction | 2024 |
| JJL Marketing Ltd | Administrative & support | 2026 |
| JJT Financial Services Limited | Professional & scientific | 2011 |
| JKD Property Limited | Real estate | 2017 |
| Jklc Consultants Limited | Other services | 2013 |
| Jklc Properties Limited | Real estate | 2019 |
| JL Acro Limited | Education | 2024 |
| JL Tech Group Limited | Information & communication | 2019 |
| JLH Partnership Limited | Professional & scientific | 2011 |
| JM ENT International Ltd | Arts & recreation | 2026 |
| JM Music Services Ltd | Arts & recreation | 2024 |
| JM Property Developers Ltd | Real estate | 2024 |
| JMB Engineering Consultant Ltd | Professional & scientific | 2022 |
| JME Carpentry & Joinery Limited | Manufacturing | 2024 |
| JME Construction (EA) Ltd | Construction | 2015 |
| JME Ltd | Manufacturing | 1986 |
| JN Home Interiors (Great Yarmouth) Ltd | Wholesale & retail | 2022 |
| JN Home Interiors (Halesworth) Ltd | Wholesale & retail | 2022 |
| JNB Installations Ltd | Other services | 2023 |
| Jocey Limited | Other services | 2023 |
| JOE Mcbride Plumbing & Heating Limited | Construction | 2015 |
| JOE Pybus Catering Ltd | Hospitality | 2024 |
| JOE Pybus Kitchens Ltd | Hospitality | 2026 |
| Joe's Jackets Ltd | Hospitality | 2025 |
| Joel Benstead Limited | Construction | 2013 |