| Into the Woods Cumbria Limited | Hospitality | 2017 |
| IOT Sense Tech Ltd | Professional & scientific | 2023 |
| Isis Surgical Limited | Health & social care | 2012 |
| Islam Issa Limited | Arts & recreation | 2020 |
| IXL Fitness Limited | Arts & recreation | 2024 |
| IXL Recruitment Ltd | Administrative & support | 2023 |
| J & a Digedan Limited | Construction | 2013 |
| J & D Cooper Limited | Hospitality | 2014 |
| J & J Graham Limited | Wholesale & retail | 2012 |
| J 4 D Electrical Ltd | Construction | 2009 |
| J B & E J Peile Limited | Agriculture & fishing | 2013 |
| J B Holliday & Sons Agriculture | Agriculture & fishing | 2018 |
| J Ball Ltd | Wholesale & retail | 2008 |
| J Dalton & SON Limited | Agriculture & fishing | 2008 |
| J Douthwaite Electrical Limited | Construction | 2025 |
| J G Parry Limited | Transport & logistics | 2003 |
| J H I Developments Ltd | Construction | 2004 |
| J N Lowther Holdings Limited | Real estate | 1975 |
| J Neilson Property Limited | Real estate | 2023 |
| J P Holliday | Agriculture & fishing | 2007 |
| J T M E Group Ltd | Construction | 2025 |
| J40 Ltd | Transport & logistics | 2019 |
| JAB Plumbing & Heating Cumbria Ltd | Construction | 2016 |
| Jabster Limited | Administrative & support | 2009 |
| JAC Sports Holdings Limited | Financial services | 2020 |
| Jack Forrester Technical Consulting Limited | Information & communication | 2016 |
| Jack Savage Ltd | Construction | 2015 |
| Jackson Family Butchers Limited | Wholesale & retail | 2015 |
| Jacob Adams Ltd | Transport & logistics | 2025 |
| Jagged Lakes Ltd | Extraterritorial | 2005 |
| James & John Graham Ltd | Wholesale & retail | 2018 |
| James B Property UK Ltd | Real estate | 2025 |
| James Joseph Consulting Ltd | Information & communication | 2018 |
| James Thornley & Sons Limited | Financial services | 1937 |
| James Turner (Developments) Limited | Real estate | 1962 |
| Jamie Bush Ltd | Construction | 2021 |
| Janheg Trading PTY Ltd | Real estate | 2015 |
| JAS Scaffolding Ltd | Construction | 2009 |
| Jaybox Limited | Manufacturing | 2005 |
| JB Morgan Place Limited | Financial services | 2023 |
| JC Human Resource Solutions Limited | Professional & scientific | 2005 |
| JC Trading Cumbria Ltd | Wholesale & retail | 2023 |
| JCM Transport Ltd | Transport & logistics | 2025 |
| JD Coaches (Cumbria) Ltd | Transport & logistics | 2021 |
| JFT Properties (Lytham) Limited | Real estate | 2025 |
| JH Planning Limited | Professional & scientific | 2023 |
| Jili Allen Limited | Extraterritorial | 2010 |
| Jill Ferrie & Associates Ltd | Real estate | 2015 |
| Jill KAY Cosmetics Limited | Other services | 2020 |
| JIM Rose UX Ltd | Information & communication | 2017 |
| JIM Walton (Penrith) Limited | Wholesale & retail | 1973 |
| JIM Walton (Properties) Limited | Administrative & support | 2003 |
| JIW Properties Limited | Construction | 2002 |
| JJ Hooftrimming Limited | Agriculture & fishing | 2023 |
| JJ Premier Tools Limited | Wholesale & retail | 2011 |
| JL Business Finance Limited | Administrative & support | 2022 |
| JLE Installations Limited | Construction | 2007 |
| JM Collective Ltd | Professional & scientific | 2023 |
| JMD Forestry Limited | Agriculture & fishing | 2015 |
| JMO Airline Consultant Ltd | Manufacturing | 2024 |
| Jode Ltd | Professional & scientific | 2025 |
| JOE Edge Consulting Ltd | Professional & scientific | 2025 |
| John Beaty Transport Limited | Transport & logistics | 2002 |
| John Dulson Limited | Construction | 2002 |
| John J. Rudd & SON Limited | Manufacturing | 2002 |
| John Jones Training Services Limited | Education | 2023 |
| John Norris of Penrith Limited | Wholesale & retail | 2004 |
| John Swift Homes Limited | Construction | 2000 |
| Jones Ledsom Property Limited | Hospitality | 2024 |
| Jones of Rayne Limited | Extraterritorial | 1987 |
| Joseph Cowper Limited | Wholesale & retail | 1899 |
| JP Plant Services Limited | Construction | 2022 |
| JPS Driver Hire Ltd | Wholesale & retail | 2020 |
| JRS Property Consulting Limited | Professional & scientific | 2013 |
| JS & MW Holdings Ltd | Professional & scientific | 2019 |
| JS Farming Ltd | Agriculture & fishing | 2023 |
| JS Plant Services Ltd | Manufacturing | 2020 |
| JSR 14 Limited | Real estate | 2026 |
| JSR 20 Limited | Real estate | 2026 |
| JSR 21 Limited | Real estate | 2026 |
| JSR Cumbrian Holdings Limited | Real estate | 2025 |
| JSR Equity Limited | Financial services | 2026 |
| JT Corporate Relocation Ltd | Hospitality | 2025 |
| JTJ Bricklaying Ltd | Construction | 2019 |
| JTM (Carlisle) Ltd | Construction | 2025 |
| Jubilee Gardens (Stainton) Limited | Real estate | 2022 |
| JUS Landscapes & Exteriors Ltd | Administrative & support | 2021 |
| Just People (HR) Limited | Administrative & support | 2021 |
| Justin RAY Ltd | Professional & scientific | 2009 |
| JW Houses Ltd | Construction | 2018 |
| JWJ Contracting Ltd | Agriculture & fishing | 2020 |
| JWW Finance Director Services Limited | Professional & scientific | 2023 |
| K Forrester & SON Limited | Construction | 2012 |
| K L 33 Ltd | Households | 2010 |
| K. G. Dudson Limited | Construction | 1981 |
| K.Feller Plumbing & Heating Limited | Construction | 2025 |
| Kaber Chapel Ltd | Hospitality | 2025 |
| Kandoo Adventures Limited | Extraterritorial | 2014 |
| Karen Addison Associates Limited | Other services | 2015 |
| Karolokr Ltd | Transport & logistics | 2025 |