| Iceni Flat Roofing Limited | Construction | 2020 |
| Iceni Motor Company Ltd | Manufacturing | 2018 |
| Iceni Partnership Limited | Other services | 2001 |
| Iceni Property Developments Limited | Construction | 2022 |
| Iceni Roofing Limited | Construction | 2020 |
| Inadan Limited | Real estate | 1999 |
| Ince Care Consultancy Ltd | Professional & scientific | 2024 |
| Ince Support Ltd | Health & social care | 2025 |
| Infact Services Limited | Administrative & support | 1991 |
| Info@Bensproperties Limited | Real estate | 2025 |
| Inform Printed Solutions Limited | Administrative & support | 2017 |
| Informed Decisions Consulting Limited | Financial services | 2017 |
| Integro E Limited | Manufacturing | 2021 |
| International Ambulances Ltd | Manufacturing | 2016 |
| Iron BED Company Limited | Real estate | 2013 |
| ISO Griffo Ltd | Manufacturing | 2026 |
| Iworks-Design Ltd | Professional & scientific | 2011 |
| J Gooch Electrical Services Limited | Construction | 2002 |
| J&K Properties (Norfolk) Ltd | Real estate | 2024 |
| J.A.Ellis Limited | Construction | 2008 |
| Jack Garrods MOT & Vehicle Repairs Ltd | Wholesale & retail | 2021 |
| James Munford Ltd | Construction | 2025 |
| Jammin Entertainments Limited | Arts & recreation | 2008 |
| Jana Market 1 Ltd | Wholesale & retail | 2023 |
| Jana Market Ltd | Wholesale & retail | 2022 |
| Janus Building Services Ltd | Construction | 2010 |
| Jarrett Investments Ltd | Financial services | 2023 |
| JBY Golf Limited | Arts & recreation | 2026 |
| JC Services (Anglia) Limited | Construction | 2004 |
| JC Services Eastern Limited | Professional & scientific | 2009 |
| JE & MJE Holdings Limited | Financial services | 2025 |
| Jedron Ltd | Manufacturing | 2023 |
| JEK Services Limited | Professional & scientific | 2001 |
| Jenemi Associates Limited | Professional & scientific | 1997 |
| Jenot Ltd | Health & social care | 2019 |
| JFM Trading Ltd | Wholesale & retail | 2016 |
| JGS Vehicle Recovery Ltd | Water & waste | 2023 |
| JLM Heating Ltd | Construction | 2021 |
| Joanne Goldsmith Photography Limited | Professional & scientific | 2024 |
| John Prendergast Consulting Ltd | Information & communication | 2016 |
| Just Lawns Ltd | Administrative & support | 2014 |
| JWL Hunstanton Limited | Hospitality | 2011 |
| K Lock Maintenance Limited | Construction | 2016 |
| Kaidel Projects Limited | Professional & scientific | 2015 |
| Kalinor Paper and Packaging Ltd | Wholesale & retail | 2019 |
| Kevin Moulton Heating, Plumbing & Bathrooms Limited | Construction | 2010 |
| Keystone CMS Ltd | Construction | 2026 |
| King's Lynn Scaffolding Limited | Construction | 2018 |
| Kingdom Electrical Solutions Ltd | Construction | 2026 |
| Kingdom Roofing and Building Ltd | Construction | 2026 |
| Kings Forest Leisure Ltd | Hospitality | 2023 |
| Kings Lynn Car Keys Limited | Wholesale & retail | 2017 |
| Kitfix UK Limited | Wholesale & retail | 2023 |
| Kj's Sizzling Scentz Ltd | Wholesale & retail | 2023 |
| KL Cars Limited | Wholesale & retail | 2019 |
| KL1 Radio Ltd | Professional & scientific | 2020 |
| Klfm Limited | Extraterritorial | 2022 |
| KMH Builders Limited | Construction | 2015 |
| Kpjvr Corporation Limited | Administrative & support | 2023 |
| KRM Elegance Hair & Beauty Ltd | Administrative & support | 2017 |
| Kroye Homes Ltd | Arts & recreation | 2022 |
| Krystal Kleaning Limited | Administrative & support | 2014 |
| Kudos Giftwrap Limited | Manufacturing | 2011 |
| KUK Sool WON Limited | Arts & recreation | 2013 |
| L K Cuts Ltd | Other services | 2024 |
| L. Todd Construction Ltd | Construction | 2020 |
| LA Properties (Norwich) Limited | Real estate | 2016 |
| Labas Shop Ltd | Wholesale & retail | 2015 |
| Laloa Ltd | Arts & recreation | 2017 |
| Land Sculpture Civils Limited | Construction | 2007 |
| Land Sculpture Limited | Administrative & support | 2018 |
| Langridge Construction Limited | Construction | 2019 |
| Langside Developments Limited | Real estate | 2001 |
| Langton Corporation Limited | Administrative & support | 2020 |
| Laserfast Ltd | Manufacturing | 2002 |
| Lcalder Ltd | Construction | 2022 |
| LDM71 Limited | Administrative & support | 2019 |
| Legacy Advancement Limited | Extraterritorial | 2015 |
| Leli's Deli & Gifts Limited | Wholesale & retail | 2024 |
| Levis Motorcycle Company Ltd | Manufacturing | 2017 |
| LG Motor Services Ltd | Wholesale & retail | 2017 |
| LGL Developments Limited | Real estate | 1994 |
| Life Beyond the Horizon CIC | Health & social care | 2018 |
| Life Pursuits Limited | Wholesale & retail | 2016 |
| Lightning Speedster Limited | Manufacturing | 2021 |
| Lingswood Limited | Arts & recreation | 2006 |
| Lionman Studios Limited | Other services | 2017 |
| Littlefire Labs Ltd | Information & communication | 2024 |
| Livelink Resource Limited | Administrative & support | 2013 |
| Longsons Limited | Real estate | 2013 |
| Lookout Archery Limited | Arts & recreation | 2020 |
| Lord Green Ltd | Construction | 2018 |
| Lost Time Tattoo Limited | Other services | 2019 |
| Lotus Rose Properties Ltd | Hospitality | 2023 |
| Lotus Rose Ventures Ltd | Real estate | 2023 |
| Lotusflower Marketing Limited | Professional & scientific | 2024 |
| Lovell and Ward Limited | Wholesale & retail | 1954 |
| LPD Windows and Doors Ltd | Construction | 2025 |
| LS Plant Limited | Construction | 2020 |
| Lsmh Services Ltd | Administrative & support | 2025 |