| JBL Building Limited | Construction | 2023 |
| JCD Solutions Ltd | Construction | 2023 |
| JCP Scaffolding Services Ltd | Construction | 2024 |
| JD Fabrication Services Limited | Professional & scientific | 2020 |
| JD Garage and Performance Centre Ltd | Wholesale & retail | 2018 |
| JDH Engineering Ltd | Professional & scientific | 2024 |
| JDL Strategies Limited | Financial services | 2012 |
| JDP Properties Ltd | Real estate | 2002 |
| Jechiu’S Ltd | Transport & logistics | 2023 |
| Jeff Fitt Limited | Construction | 2003 |
| Jennifer Hill Accountancy Services Ltd | Professional & scientific | 2023 |
| Jesse Scott Limited | Agriculture & fishing | 1958 |
| JFO Civils Limited | Construction | 2024 |
| JFO Communications Limited | Information & communication | 2020 |
| Jhmt Estates Ltd | Real estate | 2020 |
| Jitata Ltd | Health & social care | 2018 |
| Jjad Norfolk Developments Ltd | Construction | 2021 |
| JJN Holdings Limited | Real estate | 2016 |
| JJS Building Solutions Ltd | Construction | 2020 |
| JKH Financial Management Limited | Professional & scientific | 2024 |
| Jljn Ltd | Health & social care | 2024 |
| JMB Windows, Doors & Locks Limited | Construction | 2022 |
| JMC Construction (March) Limited | Construction | 2007 |
| JMC Projects Limited | Professional & scientific | 2004 |
| JMS (Wisbech) Ltd | Construction | 2019 |
| JNH Electrical Services Ltd | Construction | 2024 |
| Jodie Lewis Aquatics Ltd | Wholesale & retail | 2017 |
| Jodie Lewis Ltd | Wholesale & retail | 2017 |
| John Wake Holdings Ltd | Professional & scientific | 2010 |
| John Watson (Walpole) Limited | Agriculture & fishing | 1967 |
| Johnson BTL Ltd | Real estate | 2025 |
| JP Electrical Services & Engineers Ltd | Construction | 2026 |
| JP Environmental Maintenance Ltd | Construction | 2023 |
| JPN Electrical Services Ltd | Construction | 2026 |
| Jppy Services Ltd | Administrative & support | 2021 |
| JR Distributions Ltd | Wholesale & retail | 2025 |
| JRN and SON Ltd | Wholesale & retail | 2012 |
| JS Jewellery Limited | Wholesale & retail | 2025 |
| JS KOK Recruitment Ltd | Administrative & support | 2022 |
| JSF Consultancy Limited | Professional & scientific | 2024 |
| JTJ Developments Ltd | Construction | 2018 |
| Judds Coaches Limited | Transport & logistics | 2015 |
| Judds Tours Limited | Transport & logistics | 2021 |
| Julian & Co Property Services Ltd | Administrative & support | 2024 |
| Junior Golf Association | Arts & recreation | 2009 |
| Junior Golf Tour CIC | Arts & recreation | 2023 |
| Jupss Medical Services Limited | Health & social care | 2012 |
| Jurika Ltd | Financial services | 2024 |
| Just Go to Therapy Limited | Health & social care | 2022 |
| Justdogz Limited | Agriculture & fishing | 2016 |
| JWT Transport Services Ltd | Transport & logistics | 2013 |
| JXJ Holdings Ltd | Real estate | 2021 |
| K B Construction East Ltd | Construction | 2014 |
| K Connolly Construction Limited | Construction | 2018 |
| K Doig Limited | Financial services | 2010 |
| K Gray Services Limited | Professional & scientific | 2025 |
| K J Curson Growers Limited | Agriculture & fishing | 2006 |
| K M a Utilities Limited | Construction | 2016 |
| K Norton Electrical Limited | Construction | 2005 |
| K Norton Properties Limited | Real estate | 2015 |
| K R Building Ltd | Construction | 2021 |
| K S Contractors (Holbeach) Limited | Construction | 2003 |
| K-D-Pizza Ltd | Hospitality | 2022 |
| K.E.V.Transport Limited | Transport & logistics | 2018 |
| K.G.B.Transport Limited | Manufacturing | 1970 |
| K.N.H. Leisure Limited | Wholesale & retail | 2016 |
| K.W.A. Sprint Limited | Administrative & support | 2014 |
| K9 Applejacks Ltd | Agriculture & fishing | 2024 |
| K9 Fertility Ltd | Agriculture & fishing | 2021 |
| K9 Investigators Ltd | Administrative & support | 2021 |
| KA FIX Limited | Construction | 2023 |
| Kaia and Rose Limited | Financial services | 2022 |
| Kalin Web Service Ltd | Information & communication | 2021 |
| Kanova Consulting Limited | Professional & scientific | 2020 |
| KAS Fashion Ltd | Wholesale & retail | 2026 |
| Kate Ceeney Counselling Limited | Health & social care | 2016 |
| Katsab Limited | Wholesale & retail | 2025 |
| Kayow Nutrition Limited | Extraterritorial | 2025 |
| KB Belting Ltd | Manufacturing | 2025 |
| KB Kitchens Ltd | Wholesale & retail | 2010 |
| KB Truck Bodies Engineering Ltd | Professional & scientific | 2020 |
| Kchicken Ltd | Hospitality | 2023 |
| KCM Solutions Limited | Transport & logistics | 2012 |
| KCS Engineering Solutions Ltd | Manufacturing | 2026 |
| KDS Fabrications & Designs Limited | Manufacturing | 2025 |
| KE Haulage Ltd | Transport & logistics | 2025 |
| KEB Pharma Consulting Ltd | Professional & scientific | 2026 |
| Keble Limited | Wholesale & retail | 2017 |
| KEE Group Ltd | Manufacturing | 2023 |
| KEE Metalwork Ltd | Manufacturing | 2017 |
| Keeley & Webb Newsagents Ltd | Other services | 2024 |
| Keelings Hair Studio Limited | Other services | 2005 |
| Keen Health Care Ltd | Health & social care | 2023 |
| Keith Davies Financial Consultancy Ltd | Professional & scientific | 2025 |
| Keith Saunders Engineering Limited | Manufacturing | 2014 |
| Kelly Rayner Salon 2 Ltd | Other services | 2012 |
| Kempston Homes Limited | Construction | 2001 |
| Kerry’S Kritters Small Animal Rescue Limited | Agriculture & fishing | 2023 |
| Key Choice Properties Limited | Construction | 2003 |
| KF Electrical Solutions Limited | Construction | 2012 |