| IVY Close Setchey Limited | Households | 2010 |
| J Dack Electrics Limited | Construction | 2023 |
| J L Carpentry & Construction Ltd | Construction | 2023 |
| J M Ayres & Sons Limited | Manufacturing | 2013 |
| J Perkins Electrical Limited | Construction | 2024 |
| J W Long & Associates | | 1993 |
| J'S Swimming Pools Ltd | Other services | 2008 |
| J-Mac & Co Renewables Limited | Construction | 2022 |
| J.P-Energy Services Ltd | Professional & scientific | 2019 |
| J.Peacock & Sons Limited | Agriculture & fishing | 1946 |
| J.W.Spencer Farms Limited | Agriculture & fishing | 1966 |
| Jaam Property Ltd | Real estate | 2023 |
| Jaegin Ltd | Information & communication | 2022 |
| Jaesma Solutions Ltd | Construction | 2022 |
| Jakes Corporation Limited | Manufacturing | 2013 |
| James Stamper & Sons | | 1996 |
| Jamie Martin Anderson Limited | Construction | 2016 |
| Jamie's Bakes Ltd | Hospitality | 2021 |
| JAN Palmer Travel Limited | Administrative & support | 2019 |
| Janhatchellsendconsultancy Ltd | Education | 2023 |
| Jarli Holdings Limited | Real estate | 2024 |
| Jays Estate Agents Limited | Real estate | 2024 |
| JB Building Services Ltd | Construction | 2018 |
| Jc's on the Grill Snack Bar Ltd | Hospitality | 2024 |
| JCD Assets Limited | Real estate | 2024 |
| JCD Equities Limited | Financial services | 2019 |
| JD Development Solutions Ltd | Information & communication | 2024 |
| Jeavons Lifting Ltd | Construction | 2019 |
| Jelly Tots Limited | Education | 2014 |
| Jennifer Louise Interiors Ltd | Professional & scientific | 2026 |
| Jensons Way Management Company Limited | Households | 2023 |
| Jepa Tiny Town Ltd | Hospitality | 2026 |
| Jermy Developments Ltd | Construction | 2020 |
| Jestoch Ltd | Real estate | 2025 |
| JEZ Blackburn Bird Trapping Ltd | Agriculture & fishing | 2021 |
| JG Paving and Landscaping Ltd | Administrative & support | 2025 |
| Jg&R Limited | Wholesale & retail | 2024 |
| Jig-Saw Music Limited | Arts & recreation | 1964 |
| JJ Nails and Beauty 88 Ltd | Other services | 2023 |
| JL Engineering and Facility Management Ltd | Professional & scientific | 2025 |
| JLH Plastering Ltd | Construction | 2016 |
| JM Assistance Limited | Administrative & support | 2023 |
| JM Builders Property and Landscaping Ltd | Construction | 2026 |
| JM Distribution Services (Midlands) Ltd | Transport & logistics | 2012 |
| John Bradshaw (Farms) Limited | Hospitality | 1976 |
| John Kedar Geospatial Initiatives Ltd | Professional & scientific | 2019 |
| John Mayes Engineers Limited | Manufacturing | 2002 |
| John R Watts Services Limited | Manufacturing | 2010 |
| Jolly Good Games Design Ltd | Arts & recreation | 2015 |
| Jornal a N Ltd | Information & communication | 2017 |
| Joseph H. Consulting Limited | Financial services | 2025 |
| JP Property Improvements Ltd | Construction | 2021 |
| Jpower Ltd | Other services | 2024 |
| Julian Projects Ltd | Agriculture & fishing | 1999 |
| Julnes & Sons,Limited | Real estate | 1946 |
| Junior Jumpstart Fitness Limited | Arts & recreation | 2024 |
| Just a Thought Limited | Administrative & support | 1997 |
| Just Food Catering Ltd | Wholesale & retail | 2018 |
| Just Perfect Building Solutions Ltd | Construction | 2021 |
| Just Stay Norwich Ltd | Real estate | 2021 |
| Jw&Co Construction Ltd | Construction | 2026 |
| K & R Store Ltd | Wholesale & retail | 2023 |
| K R Bennett Limited | Real estate | 2016 |
| K Swan-Horton Ltd | Administrative & support | 2018 |
| K&A Plumber's Ltd | Construction | 2025 |
| Kaisy Limited | Manufacturing | 2013 |
| Kardemomme Bakery Ltd | Manufacturing | 2026 |
| Karile Ltd | Wholesale & retail | 2019 |
| Karl Richardson Logistics Limited | Transport & logistics | 2025 |
| Karris Sheet Metal Limited | Manufacturing | 2009 |
| Karris Welding Services Limited | Manufacturing | 2000 |
| Kasna Ltd | Wholesale & retail | 2026 |
| Kaybee Decorators Ltd | Construction | 2014 |
| Kaykee B Limited | Hospitality | 2025 |
| Kayleigh and Naomi's Cleaning Services Ltd | Administrative & support | 2025 |
| KB Sealants Ltd | Construction | 2025 |
| KBF Lettings Limited | Real estate | 2024 |
| KBF Property Ltd | Real estate | 2023 |
| KBL Properties Ltd | Real estate | 2025 |
| KDS Enterprise Limited | Wholesale & retail | 2023 |
| Kebab Star OK Ltd | Hospitality | 2023 |
| Keel Trading Ltd | Professional & scientific | 2020 |
| KEFERDIZ27 Ltd | Other services | 2025 |
| Kelly Bros. Mechanical Services Limited | Construction | 2022 |
| Kemo Limited | Manufacturing | 1997 |
| Kerridge Building Services Limited | Construction | 2026 |
| Keyes Transport Limited | Transport & logistics | 1987 |
| Keystone Development Trust | Hospitality | 2002 |
| KGR Quality Ltd | Professional & scientific | 2023 |
| Khaleesi Network Ltd | Administrative & support | 2026 |
| Kikbox Ltd | Wholesale & retail | 2023 |
| Kilverstone Estate LLP | | 2022 |
| King & Gale Services Limited | Construction | 2022 |
| Kingfisher Business Services Ltd | Professional & scientific | 2024 |
| KLB Escapes Ltd | Administrative & support | 2024 |
| Klsg Operations Ltd | Professional & scientific | 2025 |
| Knott's Yard Veterinary Practice Limited | Professional & scientific | 2009 |
| Know HOW 3 Limited | Wholesale & retail | 2018 |
| Knowlesy Transport Limited | Transport & logistics | 2019 |
| Koppispace Limited | Construction | 2020 |