| J-Toyne Haulage Ltd | Transport & logistics | 2018 |
| J. & M. Townsend Ltd. | Construction | 2002 |
| J. C. Pinto Ltd | Hospitality | 2022 |
| J. Digital Creative Limited | Information & communication | 2024 |
| J. DOE & Co Limited | Hospitality | 2024 |
| J. Eaton & SON Limited | Wholesale & retail | 2010 |
| J. Ellis Plumbing and Heating Ltd | Construction | 2017 |
| J. H. High and Co. Limited | Manufacturing | 2008 |
| J. Medler Haulage Co. Limited | Transport & logistics | 1994 |
| J. Medler Limited | Wholesale & retail | 1973 |
| J. N. Roofing Ltd | Construction | 2017 |
| J. R. Cozens Wiley Limited | Agriculture & fishing | 1963 |
| J. Riley Beet Harvesters (U.K.) Limited | Wholesale & retail | 1994 |
| J. W. Lear Limited | Financial services | 2008 |
| J.A Elite Building Ltd | Construction | 2024 |
| J.A.P.S Holdings Limited | Financial services | 2007 |
| J.A.S Business Consultancy Ltd | Professional & scientific | 2024 |
| J.A.S Welding Services Ltd | Manufacturing | 2024 |
| J.Bunn Homes (Aylsham) Limited | Real estate | 2014 |
| J.Bunn Homes (Blakeney) Limited | Construction | 2014 |
| J.Bunn Homes (Constitution Hill) Limited | Construction | 2024 |
| J.Bunn Homes (Salthouse) Limited | Construction | 2021 |
| J.Bunn Homes Limited | Professional & scientific | 2014 |
| J.C Carriages Ltd | Transport & logistics | 2026 |
| J.C. Theory Tests Ltd | Education | 2007 |
| J.C.It Services Ltd | Information & communication | 2007 |
| J.D.T. Builder Ltd | Construction | 2007 |
| J.E. Jigsaw Limited | Wholesale & retail | 2007 |
| J.Griffiths Rail Ltd | Construction | 2023 |
| J.H. and P.E. Nicholson Limited | Agriculture & fishing | 1958 |
| J.H.D Interiors Limited | Wholesale & retail | 2009 |
| J.N Brickwork Limited | Construction | 2014 |
| J.P Industrial Ltd | Construction | 2026 |
| J.R. Barnard Ltd | Real estate | 2003 |
| J.R. Hungarian Garage Ltd. | Wholesale & retail | 2025 |
| J.R. Traction Limited | Transport & logistics | 2014 |
| J.S.Bear Consultancy Ltd | Professional & scientific | 2023 |
| J.V.M.C. Investment Company Limited | Financial services | 1973 |
| J.V.P. Limited | Administrative & support | 1999 |
| J.W.Searle Designs Ltd | Professional & scientific | 2024 |
| J.Whiting Limited | Real estate | 1962 |
| J.Yossef Ltd | Health & social care | 2023 |
| J2 Services Ltd | Construction | 2022 |
| J3 Clothing Limited | Manufacturing | 2018 |
| J7 Transport Limited | Transport & logistics | 2017 |
| J76 Ltd. | Health & social care | 2014 |
| JA Building Services (Norwich) Ltd | Construction | 2019 |
| JA-K9 Ltd | Other services | 2024 |
| JAB Diving Limited | Administrative & support | 2018 |
| Jabcom Aviation Limited | Transport & logistics | 2014 |
| Jabcom Ltd | Information & communication | 1996 |
| Jacdannica Limited | Financial services | 2006 |
| Jack Afrika Publishing Limited | Information & communication | 1998 |
| Jack Garn Limited | Transport & logistics | 2013 |
| Jack Kinsey Design Limited | Professional & scientific | 2025 |
| Jack Major Haulage Limited | Transport & logistics | 2018 |
| Jack Rabbit Properties Limited | Real estate | 1991 |
| Jack Rowe Limited | Construction | 2016 |
| Jack UK Enterprise Ltd | Education | 2022 |
| Jackaman and SON (Building Contractors) Ltd | Other services | 2016 |
| Jackdaw (Norwich) Limited | Real estate | 2017 |
| Jackdrinkwater Ltd | Construction | 2019 |
| Jacket Spuds and More Ltd | Hospitality | 2026 |
| Jackias Curtains, Blinds & Interiors Ltd | Wholesale & retail | 2017 |
| Jackias Wholesale Limited | Wholesale & retail | 2018 |
| Jackie East Anglia Ltd | Hospitality | 2018 |
| Jackman Construction Company Limited | Construction | 2004 |
| Jackpot Jake Ltd | Other services | 2022 |
| Jacks Financial Limited | Financial services | 2020 |
| Jacks Property Limited | Real estate | 2022 |
| Jackson & James Ltd | Hospitality | 2026 |
| Jackson Building Services Ltd | Construction | 2014 |
| Jackson Court (Martlesham) Management Limited | Professional & scientific | 2002 |
| Jackson Lockhart Ltd | Real estate | 2017 |
| Jackson Lombard Limited | Administrative & support | 2017 |
| Jackson Smillie Properties Limited | Real estate | 2019 |
| Jacksons Car Sales Ltd | Wholesale & retail | 2025 |
| Jackstone Consulting Ltd | Professional & scientific | 2025 |
| Jacob Emzy Ltd | Real estate | 2025 |
| Jacob's Finest Limited | Manufacturing | 2010 |
| Jacobs Food Wholesale Ltd | Wholesale & retail | 2019 |
| Jacs Partnership Limited | Financial services | 2023 |
| Jacsbrand International Ltd | Wholesale & retail | 2024 |
| Jadan Engineering Limited | Professional & scientific | 2024 |
| Jadc Ltd | Construction | 2022 |
| Jade Garden (Norwich) Ltd | Hospitality | 2021 |
| Jades Financial Associates Ltd | Financial services | 2025 |
| Jaflong Indian Restaurant Limited | Hospitality | 2008 |
| Jafp Ltd | Professional & scientific | 2024 |
| JAG Renovations Ltd | Real estate | 2022 |
| Jagd Stiedl GB Ltd | Professional & scientific | 1986 |
| Jaguar Solutions Limited | Wholesale & retail | 2017 |
| Jahin Caterers Ltd | Real estate | 2017 |
| Jaibet Ltd | Professional & scientific | 2020 |
| Jaiger Process Engineering Limited | Manufacturing | 2006 |
| Jaime Zeus US Ltd | Administrative & support | 2019 |
| Jaisowe Care Ltd | Health & social care | 2020 |
| JAK Tax Consultancy Ltd | Professional & scientific | 2018 |
| Jakal Ltd | Professional & scientific | 2014 |
| Jake Brasted Carpentry Ltd | Manufacturing | 2024 |