| Johnson and Scott Ltd | Professional & scientific | 2015 |
| Johnson and Scott Trustee Limited | Extraterritorial | 2025 |
| Johnson Projects Limited | Real estate | 2010 |
| Jollycopy Group Ltd | Wholesale & retail | 2023 |
| Jomider Mohol Ltd | Hospitality | 2025 |
| Jonathan FEW Carpentry Ltd | Construction | 2018 |
| Jonathan Tole Consulting Limited | Information & communication | 2017 |
| Jones MAY Property Services Ltd | Real estate | 2026 |
| Joog Properties Ltd | Real estate | 2024 |
| Jopson Catering Limited | Hospitality | 2025 |
| Joseph Smith Racing Ltd | Arts & recreation | 2024 |
| Joshua Julian Ltd | Wholesale & retail | 2018 |
| Joyful Sweets Treats & More Ltd | Manufacturing | 2025 |
| Joyner Bolt UK Limited | Manufacturing | 2010 |
| Joywell Construction Ltd | Construction | 2012 |
| JP Safeguarding Improvement Consultancy Limited | Public administration | 2024 |
| JR Automotive (ELY) Limited | Wholesale & retail | 2020 |
| JR Constable Construction Limited | Construction | 2004 |
| JR Tools Ltd | Wholesale & retail | 2018 |
| JRH Contracts Ltd | Construction | 2020 |
| Jrspm Limited | Construction | 2016 |
| JSC Rail Services Ltd | Manufacturing | 2017 |
| Jsof Holdings Limited | Financial services | 2025 |
| JST (ELY) Ltd | Transport & logistics | 2009 |
| Jtsd Limited | Agriculture & fishing | 2013 |
| Jubilee Court (ELY) Management Company Limited | Real estate | 2007 |
| Jubilee Quay Management Company Limited | Households | 1999 |
| Juddallium Limited | Professional & scientific | 2008 |
| Judick Limited | Financial services | 2024 |
| Julia's Tea Rooms Limited | Hospitality | 2009 |
| Jultrin Properties Limited | Real estate | 2018 |
| Jurassic Bark Littleport Limited | Wholesale & retail | 2021 |
| Just Because Ltd | Professional & scientific | 2015 |
| Jvla Property Services Ltd | Real estate | 2022 |
| JYS Holding Ltd | Real estate | 2023 |
| K & J Carpenter (Properties) Limited | Real estate | 1999 |
| K B Property Services BSE Ltd | Construction | 2024 |
| K Smith Health Care Ltd | Health & social care | 2025 |
| K. & K. Mouldings Limited | Manufacturing | 1973 |
| K. Prance PHS Ltd | Construction | 2018 |
| K3 Interior Design Limited | Administrative & support | 2005 |
| K3 Produce Ltd | Wholesale & retail | 2015 |
| K6 Engineering Limited | Wholesale & retail | 2019 |
| Kaecz Ltd | Wholesale & retail | 2023 |
| Kam-Pol Limited | Wholesale & retail | 2025 |
| Kameo Recruitment Limited | Administrative & support | 2018 |
| Kanesa Retail Ltd | Construction | 2017 |
| Kape IT Consultancy Limited | Information & communication | 2012 |
| Karianne's Secret Limited | Wholesale & retail | 2015 |
| Kastra Trading LLP | | 2016 |
| Katharos Organic Limited | Administrative & support | 2010 |
| Katie's World in Property Ltd | Real estate | 2025 |
| Katoosha Wellness Limited | Other services | 2021 |
| KD Academy Ltd | Arts & recreation | 2022 |
| KD Theatre Productions Ltd | Arts & recreation | 2013 |
| Kdrb Property Ltd | Real estate | 2025 |
| Kebabshopuk Limited | Hospitality | 2025 |
| Keef Creative Limited | Professional & scientific | 2010 |
| KEM Estates Ltd | Real estate | 2024 |
| KEM Smiles Ltd | Administrative & support | 2024 |
| Kemkas Investments Limited | Hospitality | 2024 |
| Kerb Kollective Ltd | Hospitality | 2020 |
| Kerr Consulting UK Limited | Professional & scientific | 2008 |
| Kerr Systems Ltd | Professional & scientific | 2019 |
| Kerridge Property Investments Ltd | Real estate | 2025 |
| Kestrel Radar Sensors Limited | Manufacturing | 2013 |
| KG Pro-Man Limited | Hospitality | 2019 |
| KGA Supplies Ltd | Wholesale & retail | 2014 |
| Kids Club ELY Ltd | Other services | 2018 |
| Kids Inspiration & Design Services Ltd | Administrative & support | 2016 |
| KIM Johnson Limited | Manufacturing | 2002 |
| Kimchi Soup Studios Ltd | Information & communication | 2024 |
| Kinetic Smart Solutions Limited | Information & communication | 2018 |
| King Build Limited | Construction | 2014 |
| King Industrial Roofing and Cladding Limited | Construction | 2019 |
| King Systems Limited | Administrative & support | 2010 |
| King's ELY Octagon Schools Limited | Education | 2016 |
| King's Lynn Osteopathy Ltd | Health & social care | 2020 |
| King's School ELY Enterprises Limited | Hospitality | 1998 |
| Kingfisher Promotions Ltd | Manufacturing | 2004 |
| Kings Carpentry Limited | Construction | 2020 |
| Kings Lynn Vehicle Repairs Limited | Wholesale & retail | 2013 |
| Kingswill Estates Ltd | Real estate | 2019 |
| Kingswood (Cambridge Road) Management Company Ltd | Households | 2017 |
| Kinng-Jaguar Food & Logistics Ltd. | Wholesale & retail | 2020 |
| Kiplings Kitchens Limited | Wholesale & retail | 2013 |
| Kirkpatrick Consult Limited | Information & communication | 2007 |
| KIT U OUT (UK) Limited | Manufacturing | 2006 |
| Kivi Ketts Hill Ltd | Real estate | 2024 |
| Kjandmnm Limited | Wholesale & retail | 2024 |
| KJM Training Limited | Administrative & support | 2012 |
| Klvr Holdings Limited | Professional & scientific | 2020 |
| Klvr Properties Limited | Real estate | 2020 |
| Knitfashion Ltd | Manufacturing | 2025 |
| Knot Normal Solutions Ltd | Hospitality | 2026 |
| Koch Capital Ltd | Professional & scientific | 2019 |
| Konieczny Limited | Transport & logistics | 2024 |
| Kovelston Europe Limited | Financial services | 2013 |
| KP Insulation Ltd | Construction | 2010 |
| Kpns International Limited | Professional & scientific | 2020 |