| Inixia Health Limited | Information & communication | 2023 |
| Inpud | Health & social care | 2013 |
| Inside Story Films Limited | Information & communication | 2025 |
| IP Cabling Ltd | Information & communication | 2025 |
| Isle of ELY KOI Ltd | Agriculture & fishing | 2002 |
| IVY Site Management Company Limited | Real estate | 2025 |
| J Barham Driver Hire Ltd | Transport & logistics | 2010 |
| J H Engineering (Bexwell) Limited | Manufacturing | 2006 |
| J&H Scaffolding Ltd | Construction | 2025 |
| J.D'Signs Limited | Wholesale & retail | 2008 |
| J.R Developments (Eastern) Ltd | Real estate | 2021 |
| J.R. Johnson Limited | Wholesale & retail | 1998 |
| JAG Developments Limited | Real estate | 2024 |
| Javea Investments Limited | Financial services | 2020 |
| JC Event Hire Ltd | Hospitality | 2025 |
| Jcnb Crafts Limited | Manufacturing | 2022 |
| JET Accountancy (Norfolk) Ltd | Professional & scientific | 2014 |
| Jewellabel Limited | Information & communication | 2023 |
| JG Property & Investment Holdings Limited | Real estate | 2025 |
| JL Finishing Ltd | Construction | 2022 |
| JM11 Holdings Ltd | Real estate | 2021 |
| JM7 Property Limited | Financial services | 2019 |
| Jmtechnical Designs Ltd | Professional & scientific | 2020 |
| Jmtechnical Holdings Ltd | Financial services | 2023 |
| Jmtechnical Manufacturing Ltd | Manufacturing | 2012 |
| JR Timbersourcing UK Limited | Professional & scientific | 2024 |
| JS Rose Holdings Ltd | Financial services | 2023 |
| JTS Associates Limited | Construction | 2013 |
| Jurassic Bark Ltd | Wholesale & retail | 2012 |
| Jurassic Land Limited | Real estate | 2018 |
| Jventures Ltd | Financial services | 2022 |
| K E Rawlings (Holdings) Limited | Construction | 2004 |
| K E Rawlings Limited | Construction | 2021 |
| Karma Enterprises EOT Limited | Administrative & support | 2018 |
| Karma Enterprises Limited | Hospitality | 2006 |
| Karma Land and Property Limited | Construction | 2016 |
| Karma Regenerational Ltd | Construction | 2024 |
| Keeping Count Limited | Professional & scientific | 2013 |
| Keith Alan Limited | Wholesale & retail | 2016 |
| Kentek Design Services Limited | Professional & scientific | 1976 |
| Kewright Renewables Ltd | Construction | 2024 |
| KHC Group UK Limited | Wholesale & retail | 2019 |
| Kind Chemicals Ltd | Manufacturing | 2024 |
| Kingfisher (Norfolk) Ltd | Administrative & support | 2018 |
| Kings Lynn Speedway Ltd | Arts & recreation | 2021 |
| Komplete Metanoia Ltd | Administrative & support | 2025 |
| Ktcm Ltd | Real estate | 2018 |
| Kula Group Limited | Administrative & support | 2021 |
| L & R Eggs Ltd | Wholesale & retail | 2025 |
| L and a Lockhart Limited | Financial services | 2015 |
| L&C Accommodation Limited | Hospitality | 2025 |
| L.D Electrical Installations Ltd | Construction | 2022 |
| Lagonda Media Holdings Ltd | Professional & scientific | 2022 |
| Lakes Property Limited | Construction | 2010 |
| Lakroholding UK Limited | Wholesale & retail | 2022 |
| Langley's Ultimate Ltd | Administrative & support | 2023 |
| Langleys Building Services Ltd | Construction | 2008 |
| Lazy Lakes Developments Ltd | Construction | 2026 |
| LCM Developments Ltd | Households | 2018 |
| Leadchase Ltd | Information & communication | 2026 |
| Lean Easy Limited | Professional & scientific | 2019 |
| Leatone Limited | Other services | 2023 |
| LEE Bishop Carpentry & Construction Ltd | Construction | 2020 |
| LEE Williams Electrical and Sons Limited | Construction | 2014 |
| Leigh Clark Autocare Centre Limited | Wholesale & retail | 2009 |
| Leisure and Utility Limited | Wholesale & retail | 2019 |
| Leyline Transport Ltd | Transport & logistics | 2021 |
| Libra Recruitment Ltd | Administrative & support | 2019 |
| Lilac Farming Ltd | Agriculture & fishing | 2021 |
| LILYWHITE63 Limited | Extraterritorial | 1995 |
| Lincoln JB Property Ltd | Real estate | 2024 |
| Lindon Property Ltd | Construction | 2023 |
| Lines Developments Ltd | Construction | 2020 |
| Linke & Lyons Motor Group Limited | Wholesale & retail | 2022 |
| Liquid Screed Pumping Ltd | Construction | 2021 |
| Little Beans Play Cafe Ltd | Hospitality | 2025 |
| Little Chippy(Downham Market) Limited Limited | Wholesale & retail | 2026 |
| Lizzie Walker Limited | Wholesale & retail | 2020 |
| LJB Management Limited | Real estate | 2026 |
| LJB Stays Ltd | Real estate | 2025 |
| LJB Suites Limited | Hospitality | 2026 |
| LM Law Scientific Writing Ltd | Professional & scientific | 2025 |
| LNG Langley Ltd | Wholesale & retail | 2025 |
| Location Group Limited | Financial services | 2020 |
| Look OUT Music Ltd | Information & communication | 2024 |
| Ludo's Kitchen Ltd | Hospitality | 2023 |
| Lydon Land and Water Ltd | Administrative & support | 2024 |
| Lynn F.C. Limited | Arts & recreation | 2009 |
| LYNNCONNECT1 LLP | | 2019 |
| Lynwere Engineering Ltd | Construction | 2011 |
| M and H Giddings Limited | Construction | 2007 |
| M L J Property Development Limited | Real estate | 2008 |
| M. R. S. Developments Ltd | Construction | 2019 |
| M.A. Engineering (EA) Limited | Administrative & support | 2007 |
| M2 Halls Developments Ltd | Real estate | 2025 |
| M7 Technologies Limited | Information & communication | 2026 |
| Macklips Ltd | Manufacturing | 2018 |
| Macks Grounds Ltd | Administrative & support | 2025 |
| Maiden Outdoor Advertising Ltd | Professional & scientific | 2024 |
| Make ME Digital Ltd | Professional & scientific | 2021 |