| J C Repairs Limited | Professional & scientific | 2023 |
| J&C Realty Limited | Real estate | 2024 |
| J&D Logistics Limited | Transport & logistics | 2007 |
| J'S Collectors Vault Ltd | Wholesale & retail | 2025 |
| J. Taylor Horseboxes Ltd | Manufacturing | 2019 |
| J. W. Abbey Ltd | Information & communication | 2026 |
| J.B.E.S Electrical Ltd | Construction | 2024 |
| J.J.Mason Electrical Ltd | Construction | 2026 |
| J.Shave Services Limited | Construction | 2014 |
| JAC Technologies Limited | Administrative & support | 2016 |
| Jade Personnel Ltd | Administrative & support | 2018 |
| Jaig Ltd | Construction | 2026 |
| Jane Long Ltd | Professional & scientific | 2015 |
| Jark (Belfast) Limited | Administrative & support | 2016 |
| Jark (Cambridge) Limited | Administrative & support | 2016 |
| Jark (Downpatrick) Limited | Administrative & support | 2016 |
| Jark (Peterborough) Limited | Administrative & support | 2016 |
| Jark (Stevenage) Limited | Administrative & support | 2016 |
| Jark (Wakefield) Limited | Administrative & support | 2016 |
| Jark (Warrington) Ltd | Administrative & support | 2017 |
| Jark (Worcester) Limited | Administrative & support | 2016 |
| Jark Ventures Limited | Professional & scientific | 1996 |
| Jarvis and Jarvis Ltd | Real estate | 2012 |
| Jason Harrison Carpets & Flooring Ltd | Construction | 2019 |
| JAY Chitty Driving Ltd | Transport & logistics | 2025 |
| JCS (Norfolk) Ltd | Other services | 2024 |
| JCS Befrienders Ltd | Health & social care | 2026 |
| JD Agghaul Ltd | Transport & logistics | 2023 |
| JE Spark Ventures Ltd | Wholesale & retail | 2026 |
| Jean Lion & Company Limited | Agriculture & fishing | 2015 |
| JED Duffield Flooring Ltd | Wholesale & retail | 2024 |
| JEM Packaging Limited | Manufacturing | 2002 |
| Jemmett FOX (UK) Limited | Professional & scientific | 2006 |
| Jemmett FOX Company Services Limited | Administrative & support | 2008 |
| Jemmett FOX Media Limited | Information & communication | 2009 |
| Jensen Bike UK Ltd | Wholesale & retail | 2015 |
| JF Corporate Services Provider Ltd | Administrative & support | 2025 |
| Jgas Air Conditioning Ltd | Construction | 2022 |
| JH Electrical (Norwich) Ltd | Construction | 2023 |
| JHS Effects Limited | Information & communication | 2024 |
| JJ Nails & Beauty DNJ Ltd | Other services | 2024 |
| JJG Services Limited | Manufacturing | 2015 |
| JK Tiling Contractors Ltd | Construction | 2017 |
| JL Roofing & Property Maintenance Ltd | Construction | 2025 |
| JLC Products Ltd | Wholesale & retail | 2020 |
| JLC Properties Ltd | Real estate | 2020 |
| JLC Security Professionals Limited | Administrative & support | 2014 |
| JMB Supplies Limited | Wholesale & retail | 2022 |
| JME Transport & Logistics Ltd | Transport & logistics | 2024 |
| JMH Electrical Services Ltd | Construction | 2023 |
| JMS Taxis Dereham Ltd | Transport & logistics | 2026 |
| Jody LEE Limited | Other services | 2013 |
| Joff Limited | Real estate | 1997 |
| John Coles Services Ltd. | Construction | 2016 |
| Johnson Hire & Sales Limited | Administrative & support | 2013 |
| Jonathan Cheetham (Contracting) Limited | Agriculture & fishing | 1998 |
| Jordan Young Independent Funeral Home Limited | Other services | 2021 |
| Josh Farrow Limited | Transport & logistics | 2011 |
| JP2 Projects Limited | Hospitality | 2012 |
| JPG Auto Services Ltd | Wholesale & retail | 2013 |
| JRP Education Ltd | Education | 2015 |
| JSG Mendham & Co Limited | Professional & scientific | 2002 |
| Jude Jones Limited | Construction | 2012 |
| Jungle Public Relations Limited | Professional & scientific | 2006 |
| Justin Steward Clearances Limited | Water & waste | 2026 |
| JXL Solutions Limited | Professional & scientific | 2022 |
| K & L Self Move Ltd | Administrative & support | 2025 |
| K Beales Plant Hire & Contracting Ltd | Construction | 2022 |
| K D Thomas Plumbing & Heating Ltd | Construction | 2014 |
| K G Sadd Property Maintenance Limited | Construction | 2014 |
| K Murphy Installations Limited | Construction | 2008 |
| K Palmer Decorating Services Ltd | Construction | 2021 |
| K&C Telecommunications Ltd | Information & communication | 2020 |
| Kaiem Property Ltd | Hospitality | 2023 |
| Kapow Toys Limited | Wholesale & retail | 2009 |
| Kappa Investments Limited | Real estate | 1990 |
| Karma Moments Ltd | Professional & scientific | 2020 |
| Kaushal Investment Group Ltd | Professional & scientific | 2002 |
| Kavakinhos Ltd | Wholesale & retail | 2024 |
| Kayleigh Limited | Real estate | 1999 |
| Keith Farms Limited | Agriculture & fishing | 1997 |
| Kensington Land Projects Ltd | Construction | 2026 |
| Kensington Lodge Farm Ltd | Agriculture & fishing | 2025 |
| Kentford House Management Company Limited | Extraterritorial | 2025 |
| Kerostech Limited | Information & communication | 2024 |
| KFS 2014 Limited | Agriculture & fishing | 2014 |
| Kicareds Limited | Professional & scientific | 2005 |
| Kickstart Norfolk | Wholesale & retail | 2003 |
| KIG Estate Ltd | Health & social care | 2016 |
| Kilgour Connolly Properties Limited | Real estate | 2019 |
| Kimblewick Equestrian Centre LLP | | 2024 |
| Kinda Productions Ltd | Hospitality | 2024 |
| Kingfisher Roofing Norfolk Ltd | Construction | 2020 |
| Kingtimber Ltd | Administrative & support | 2019 |
| KMS Mortgages Limited | Financial services | 2023 |
| Knight & Jones Recruitment Limited | Administrative & support | 2019 |
| Know Your Roots Limited | Information & communication | 2025 |
| Koba Protection Limited | Administrative & support | 2020 |
| Kokowest Ltd | Wholesale & retail | 2024 |
| Kookaburra Enterprises Limited | Hospitality | 2008 |