| Joe's Decor Ltd | Construction | 2024 |
| Jolly Vehicle Operations Ltd | Transport & logistics | 2025 |
| Josum Limited | Professional & scientific | 2024 |
| JP Bowles Plumbing and Heating Ltd | Construction | 2025 |
| JPJ Investments Limited | Real estate | 2017 |
| JR Daly Ltd | Wholesale & retail | 2022 |
| JRN Decorating Limited | Construction | 2022 |
| JRP Construction (Norfolk) Ltd | Construction | 2017 |
| JTC Design Services Limited | Professional & scientific | 2005 |
| Jubilee Lodge Development Limited | Construction | 2020 |
| Jurkiewicz Ltd | Transport & logistics | 2025 |
| JW Automarine Ltd | Manufacturing | 2020 |
| K S P Specialist Decorators Limited | Construction | 2009 |
| K Valley Limited | Professional & scientific | 2007 |
| Kemp Retail Ltd | Wholesale & retail | 2023 |
| Kendroon Ltd | Administrative & support | 1996 |
| Kent & Cleal Ltd. | Manufacturing | 1913 |
| Ketts Electrical Ltd | Construction | 2017 |
| Key Consultants Limited | Professional & scientific | 2020 |
| King's Lynn VW Centre Limited | Wholesale & retail | 2003 |
| Kings & Barnhams Group Limited | Financial services | 2013 |
| Kinnerton (Confectionery) Co. Limited | Manufacturing | 1978 |
| Kirby & Clare LLP | | 2014 |
| KJ Daniels Limited | Education | 2023 |
| Knowles & Wright (Developments) Limited | Construction | 2002 |
| Krusty Loaf Ltd | Manufacturing | 2007 |
| Lake Bryan Limited | Professional & scientific | 2020 |
| Lakeshore Healthcare Limited | Health & social care | 2006 |
| Lamberts Potatoes Ltd | Wholesale & retail | 2011 |
| Lammiman Electrical Limited | Construction | 2011 |
| Land Graves Management Company (L.G.M.C) LLP | | 2022 |
| Langham Developments Limited | Construction | 2018 |
| Langham Glass Limited | Manufacturing | 1996 |
| Law Library Services Limited | Arts & recreation | 2018 |
| Lawrence Fibrous Plastering Ltd | Construction | 2021 |
| Learn 2 Live Life CIC | Education | 2024 |
| Leci Capital Hand Car Wash Ltd | Other services | 2012 |
| LEF Trading Limited | Construction | 2018 |
| Leicester Square Farm Management Limited | Households | 2000 |
| Less Messy Ltd | Arts & recreation | 2024 |
| Letts Renovate Ltd | Construction | 2025 |
| LEV Alexander Limited | Professional & scientific | 2023 |
| Lexham Engineering Ltd | Wholesale & retail | 2022 |
| Light Brown Partnership LLP | | 2014 |
| Lightwaves Limited | Construction | 1992 |
| Lime Kiln Farm Sports Horses and Ponies Limited | Wholesale & retail | 2021 |
| Liquid Icons Limited | Information & communication | 2014 |
| LIV Architects Limited | Professional & scientific | 2018 |
| LMG Agriplant Ltd | Wholesale & retail | 2023 |
| LMJ Brown Estates Limited | Real estate | 2025 |
| Loida Ltd | Professional & scientific | 2018 |
| Lookhere Solutions Limited | Information & communication | 2023 |
| LUX Box Lighting Technology Limited | Manufacturing | 2010 |
| LUX Energy and Renewables Limited | Construction | 2024 |
| Luxehouse Stays Ltd | Real estate | 2026 |
| LWI Developments Ltd | Construction | 2018 |
| Lyng Garage Limited | Wholesale & retail | 2008 |
| Lynnmoore Engineering Company Limited | Professional & scientific | 1994 |
| Lyons of London Ltd | Information & communication | 2020 |
| M & a Kemp Limited | Construction | 2006 |
| M K M Suckling Limited | Other services | 2003 |
| M L Walsingham & SON Limited | Wholesale & retail | 2000 |
| M T Daniels Developments Limited | Construction | 2022 |
| M Webster (Holdings) Limited | Construction | 2019 |
| M. English Security Ltd | Construction | 2003 |
| M.D. Williamson Carpets Ltd. | Wholesale & retail | 2003 |
| Mackhouse Landfill Solutions Ltd | Water & waste | 2017 |
| Macrosoft Media Limited | Other services | 2007 |
| Major Medical Assistance Limited | Health & social care | 2022 |
| Marcus H Oliver Pigs Limited | Agriculture & fishing | 2011 |
| Mark Harries Ltd | Administrative & support | 2008 |
| Mark Reed Services Ltd | Administrative & support | 2014 |
| Martin Woods Plumbing & Heating Ltd | Construction | 2025 |
| MB Design Studio Ltd | Professional & scientific | 2020 |
| Mckay Autosports Ltd | Wholesale & retail | 2019 |
| Mday Investment Ltd | Real estate | 2024 |
| Medeggs Ltd | Wholesale & retail | 2022 |
| MEG Mekushin Ltd | Hospitality | 2021 |
| Megachest Ltd | Wholesale & retail | 2023 |
| Mei's CHA Limited | Administrative & support | 2023 |
| Melinamedia Ltd | Information & communication | 2014 |
| Meraki Marquees Ltd. | Administrative & support | 2018 |
| Merlebank Freehold Limited | Real estate | 2021 |
| Michael Wood Consultancy Ltd | Professional & scientific | 2013 |
| Micronized Food Products Limited | Manufacturing | 2014 |
| Mikkelsen Kvant LLP | | 2017 |
| Mistley Waterworks Limited | Extraterritorial | 1995 |
| Mitchell and Moth Ltd | Professional & scientific | 2026 |
| MMC Imports Limited | Financial services | 2026 |
| Moorlands Cheesemakers Limited | Hospitality | 2001 |
| Moreton Limited | Professional & scientific | 2018 |
| Morris & Alexander Limited | Manufacturing | 2000 |
| Morston Anchor Limited | Hospitality | 2010 |
| Morton Hall Farms Limited | Agriculture & fishing | 1964 |
| MOW Spares Ltd | Wholesale & retail | 2013 |
| MR T'S Renovations & Plastering Ltd | Construction | 2017 |
| Mulberry Homes (Norfolk) Limited | Construction | 2017 |
| Multi Mechanics Limited | Manufacturing | 2008 |
| Museum of Dogs Ltd | Arts & recreation | 2022 |
| MYM Games Ltd | Manufacturing | 2025 |