| JD Pavers Limited | Administrative & support | 2017 |
| JD Roofing and Building Ltd | Construction | 2024 |
| JDA Bodyworks Ltd | Wholesale & retail | 2024 |
| JDB Joinery Limited | Construction | 2022 |
| Jdscott Holdings Ltd | Education | 2021 |
| Jeceris Limited | Professional & scientific | 2014 |
| Jeff Carruthers Limited | Construction | 2003 |
| Jeffreys Woodstock Limited | Arts & recreation | 2021 |
| JEL Marketing Limited | Professional & scientific | 2025 |
| Jeremy Robinson Project Management Limited | Professional & scientific | 2019 |
| Jersey Cattle Society of the United Kingdom(The) | Agriculture & fishing | 1883 |
| Jess Ariel Ltd | Information & communication | 2020 |
| JF Bowers Family Investments Ltd | Financial services | 2018 |
| JF Smith Engineering Limited | Construction | 2011 |
| JFC Executive Coaching Ltd | Education | 2012 |
| JG Rural & Agricultural Services Ltd | Agriculture & fishing | 2022 |
| JGW Property Services Limited | Construction | 2024 |
| Jigsaw (Cumbria) Limited | Construction | 2017 |
| Jigsaw Business Networks Limited | Information & communication | 2004 |
| JIJ Civils Ltd | Construction | 2026 |
| Jill Glencross Independent Funeral Directors Ltd | Other services | 2020 |
| JJ Group (Contracting) Holdings Ltd | Financial services | 2026 |
| JJ Group (Contracting) Limited | Construction | 2001 |
| JJD Control Systems Limited | Administrative & support | 2023 |
| JJL Properties Limited | Real estate | 2014 |
| JJM Networks Limited | Information & communication | 2011 |
| JJM Plant Operator Services Ltd | Construction | 2018 |
| Jjt-Pm Limited | Construction | 2023 |
| JKF Haulage Limited | Transport & logistics | 2015 |
| JL Irving Limited | Professional & scientific | 2014 |
| JLB Commerce Limited | Wholesale & retail | 2024 |
| JLB Retail Group Limited | Wholesale & retail | 2024 |
| Jlee-Thompson Ltd | Transport & logistics | 2026 |
| Jlmp Logistics Ltd | Transport & logistics | 2025 |
| JLT Plant Limited | Administrative & support | 2015 |
| JM Treecare & Landscaping Ltd | Administrative & support | 2024 |
| JMC National Ltd | Hospitality | 2023 |
| JMR Deliveries Ltd | Transport & logistics | 2025 |
| JMT Trade Ltd | Wholesale & retail | 2006 |
| JN Personal Training Carlisle Ltd | Arts & recreation | 2025 |
| JOC Finanziario Ltd | Real estate | 2025 |
| Jocaule Jewellery Workshop Ltd | Manufacturing | 2022 |
| Jock Services Ltd | Professional & scientific | 2026 |
| JOE O'Donoghue Plastic Surgery Ltd | Health & social care | 2024 |
| Joelle's Hair Styling Limited | Other services | 2016 |
| John Carrick Building Limited | Construction | 2014 |
| John Fraser Roofing Limited | Construction | 2004 |
| John Hartley Leisure Limited | Arts & recreation | 2011 |
| John Moore and Sons (Builders) Limited | Construction | 2004 |
| John Penn Limited | Administrative & support | 2008 |
| John Robert Gardens Management Company NO 1 Limited | Households | 2007 |
| John Simpson (Carlisle) Limited | Construction | 1952 |
| John Watt Catering Limited | Hospitality | 2021 |
| John Williams Landscape & Fencing Ltd | Administrative & support | 2013 |
| John&Sons Concrete Contractors Ltd | Construction | 2022 |
| Johnson Macadam Limited | Professional & scientific | 2003 |
| Johnston & SON (Cumbria) Limited | Real estate | 2022 |
| Johnston Courier Ltd | Transport & logistics | 2025 |
| Johnston Engineering Group Limited | Manufacturing | 2016 |
| Johnston Excavators Ltd | Wholesale & retail | 2018 |
| Johnston Tractors Limited | Wholesale & retail | 2011 |
| Joicey’S Trade Ltd | Households | 2025 |
| Joining Forces Limited | Administrative & support | 2021 |
| JON Owen Ltd | Education | 2026 |
| Jonacate Consultancy Ltd | Information & communication | 2013 |
| Jonathan Wilkes Limited | Arts & recreation | 2002 |
| Jones & Harlington Ltd | Professional & scientific | 2024 |
| Jones Active Ltd | Information & communication | 2009 |
| Jones Civils Ltd | Construction | 2019 |
| Jopsons Jewellers Ltd | Wholesale & retail | 2018 |
| Jordan Jones Ltd | Transport & logistics | 2026 |
| Jorvik Design Group Ltd | Professional & scientific | 2019 |
| Joseph Invest Ltd | Financial services | 2021 |
| Joshua Price Ltd | Information & communication | 2022 |
| Joy Pizza Limited | Hospitality | 2024 |
| Joylan Farms Limited | Agriculture & fishing | 2006 |
| JP Brokers Limited | Financial services | 2026 |
| JP Kitchens Limited | Construction | 2002 |
| JP Payrolls Ltd | Professional & scientific | 2016 |
| JP Ward Ltd | Professional & scientific | 2023 |
| JP5 Development Ltd | Real estate | 2020 |
| JPL RA Services Ltd | Construction | 2025 |
| JR Electrical Services (Carlisle) Ltd | Construction | 2026 |
| JR Flooring Carlisle Ltd | Construction | 2024 |
| JR Tree Services Ltd | Agriculture & fishing | 2015 |
| JRB Contracting Ltd | Construction | 2025 |
| JRB Masonry Ltd | Construction | 2022 |
| JRD Roofing Ltd | Construction | 2023 |
| JRM Global Solutions Ltd | Professional & scientific | 2025 |
| JRM Property Development Ltd | Real estate | 2025 |
| JS (Northern) Ltd | Construction | 2023 |
| JS Group Capital Ltd | Financial services | 2026 |
| JS Roofing Supplies Ltd | Wholesale & retail | 2026 |
| JS Technical Solutions Ltd | Other services | 2023 |
| JS Thwaytes Ltd | Transport & logistics | 2021 |
| JS Timeless Roofing Ltd | Construction | 2025 |
| JS Wind Ltd | Manufacturing | 2021 |
| JSP Driver Services Ltd | Transport & logistics | 2019 |
| JSR Property Works Limited | Construction | 2025 |
| JT Farming Ltd | Agriculture & fishing | 2025 |