| Ikon Film Studios Ltd | Arts & recreation | 2023 |
| Intelligent Entertainment Services LLP | | 2019 |
| Inuti Global Limited | Construction | 1968 |
| Invest Norfolk Ltd | Construction | 2019 |
| Itec Remarketing Ltd | Wholesale & retail | 2017 |
| IV Services Kings Lynn Ltd | Wholesale & retail | 2024 |
| J Finney Painters and Decorators Ltd | Construction | 2019 |
| J Leman & Sons Limited | Agriculture & fishing | 2014 |
| J P Home & Garden Services Limited | Other services | 2013 |
| J R J Joplin Limited | Transport & logistics | 2024 |
| J S Agricultural Services Ltd | Wholesale & retail | 2023 |
| Jack Oughton Electrical Services Ltd | Construction | 2015 |
| Jacks Restaurant at Woodlakes Ltd | Hospitality | 2020 |
| James Yemc Golf Limited | Other services | 2017 |
| Janbeck Limited | Professional & scientific | 2005 |
| JAX Property Maintenance Limited | Construction | 2023 |
| JBE Services Limited | Construction | 2006 |
| JDS Construction (Norfolk) Limited | Construction | 2003 |
| Jean Services Ltd | Other services | 2023 |
| JK Build Services Ltd | Administrative & support | 2016 |
| JLM Scaffolding Ltd | Construction | 2019 |
| JM Integrated Systems Ltd | Administrative & support | 2025 |
| Jneadley Autorepairs Ltd | Wholesale & retail | 2025 |
| John Mcneil Wilson Limited | Agriculture & fishing | 1948 |
| Johnsons Removals Ltd | Transport & logistics | 2019 |
| Jordan Fabrications Ltd | Manufacturing | 2021 |
| K L Technologies (Properties) Ltd | Real estate | 2011 |
| K L Technologies Limited | Financial services | 2007 |
| K Rawlings Electrical Contractors Ltd | Construction | 2019 |
| K. Prior Window Repairs Limited | Construction | 2003 |
| Kelly Pratt Ltd | Health & social care | 2016 |
| Kesto Car Services Limited | Wholesale & retail | 2016 |
| Keystone Ceramics Limited | Other services | 2017 |
| Kings Lynn Guns and Country Clothing Ltd | Professional & scientific | 2011 |
| Kings Lynn Warehousing Limited | | 1983 |
| Kingswall (Hyundai) Limited | Transport & logistics | 2004 |
| Kirby Court (Kings Lynn) Management Limited | Households | 2008 |
| KLB Creative Limited | Other services | 2022 |
| Klimatech Limited | Energy | 2008 |
| KLR Fitness Ltd | Arts & recreation | 2022 |
| Kmtn Developments Limited | Construction | 2025 |
| KW Metal Products Ltd | Manufacturing | 2023 |
| L Molyneux Construction Limited | Construction | 2015 |
| L&T Ventures Ltd | Wholesale & retail | 2026 |
| L. English Country Gardens & Landscapes Ltd | Administrative & support | 2025 |
| Laen Limited | Real estate | 2002 |
| Laketree Ltd | Manufacturing | 2023 |
| Larchwood Foods Limited | Manufacturing | 2010 |
| Larson Roofing Ltd | Construction | 2021 |
| LB Waste Management Limited | Water & waste | 2022 |
| LDR Physiotherapy Services Ltd | Health & social care | 2020 |
| LEE Hardy Racing Ltd | Arts & recreation | 2012 |
| LEN Plain Limited | Construction | 2002 |
| Lexham Grain Store LLP | | 2011 |
| Lime Street Consultants Ltd | Professional & scientific | 2015 |
| Little Chippy(Litcham) Ltd | Wholesale & retail | 2026 |
| LJ Aesthetics Norfolk Ltd | Other services | 2020 |
| Longworth Electrical Ltd | Construction | 2015 |
| Lotus Flooring (Cambs) Limited | Construction | 2020 |
| Lucas Engineering Ltd | Professional & scientific | 2022 |
| Lugden Hill Farms Limited | Agriculture & fishing | 2018 |
| Lula's Burger and Barbecue Limited | Hospitality | 2020 |
| Lush HCW Ltd | Other services | 2025 |
| Lushers (Mechanical & Electrical) Ltd | Construction | 2023 |
| Lushers Ltd | Construction | 2021 |
| Lynedoch and Scott Limited | Real estate | 2015 |
| Lynn Coffee Ltd | Hospitality | 2025 |
| Lynnform Ltd | Manufacturing | 2026 |
| Lynnframe Limited | Construction | 2016 |
| Lynwood Growers Limited | Agriculture & fishing | 2009 |
| M T Groundworks Limited | Construction | 2010 |
| M. Cholerton Building Limited | Construction | 2007 |
| M. S. Formwork (Norfolk) Limited | Construction | 2005 |
| M.A.C Electrical Services and Installations Limited | Construction | 2022 |
| MA Elec Plumbing & Heating Ltd | Construction | 2004 |
| Macca Tree Holdings Ltd | Real estate | 2021 |
| Madame Big Mouth Ltd | Hospitality | 2021 |
| Mapish Ltd | Health & social care | 2017 |
| Mare Forza 10 Limited | Extraterritorial | 2006 |
| Marham Hall Farms Limited | Agriculture & fishing | 1959 |
| Mark J Higby Limited | Construction | 2005 |
| Marriotts Landscapes Ltd | Construction | 2020 |
| Mars Property Management Limited | Real estate | 2004 |
| Marshlands Holdings Limited | Information & communication | 2025 |
| Massingham Manor LLP | | 2024 |
| MAT Smith Sports Cars Limited | Wholesale & retail | 2012 |
| Maurice Mason Limited | Agriculture & fishing | 1947 |
| MC Maintenance and Improvements Ltd | Construction | 2016 |
| Mccavity’S Contract Fillers Limited | Administrative & support | 2016 |
| Mcfadden & Hough Construction Limited | Construction | 2017 |
| Mcfadden & Hough Limited | Construction | 2012 |
| Mechanical ENG Ltd | Professional & scientific | 2025 |
| Med-Pts Ambulance Services Ltd | Transport & logistics | 2018 |
| Medalright Limited | Real estate | 1988 |
| Mel-Able Farming Limited | Agriculture & fishing | 1966 |
| Melton Hall Limited | Arts & recreation | 1993 |
| Melton Park Wellness Group Ltd | Health & social care | 2024 |
| Memories in Crystal Ltd | Extraterritorial | 2016 |
| MFJ Associates Ltd | Professional & scientific | 2012 |
| MG Engineering (KL) Limited | Professional & scientific | 2015 |