| JOE the CAB Ltd | Transport & logistics | 2014 |
| Joel Avery Design Ltd | Professional & scientific | 2018 |
| JOG Sports Apparel and Equipment Ltd | Wholesale & retail | 2017 |
| John Baldwin Tavistock Limited | Wholesale & retail | 2007 |
| John Barter Transport (South West) Limited | Transport & logistics | 2016 |
| John Blackmore & Co Limited | Professional & scientific | 2000 |
| John Card Accident Repair Centre Ltd | Wholesale & retail | 2013 |
| John Casson Consultancy Limited | Other services | 1999 |
| John Clarke & SON (Midlands) Limited | Other services | 2003 |
| John Walter Parson Ltd | Extraterritorial | 2020 |
| John Watkins Group Limited | Financial services | 2018 |
| Johnprees Ltd | Construction | 2024 |
| Jojobee Ltd | Administrative & support | 2026 |
| Joka’S Bar Ltd | Hospitality | 2024 |
| Jolly's Drinks Limited | Manufacturing | 2018 |
| Jollyganza Event Management Limited | Hospitality | 2025 |
| Jolton Property Ventures Ltd | Real estate | 2022 |
| JON Lyon Farriery Services Ltd | Other services | 2015 |
| Jonathan Case Builders & Contractors Limited | Construction | 2007 |
| Jonathan O'Brien Consulting Limited | Professional & scientific | 2013 |
| Jonathanmiller Limited | Extraterritorial | 2025 |
| Jones Maintenance Ltd | Construction | 2017 |
| Jones Seafoods Limited | Extraterritorial | 2021 |
| Jones the Nomad Ltd | Administrative & support | 2017 |
| Jonnysdreams Ltd | Wholesale & retail | 2025 |
| Joseph Dunn Architecture Limited | Professional & scientific | 2018 |
| Joseph Mason Limited | Real estate | 2014 |
| Joseph Sail Properties Ltd | Real estate | 2024 |
| Josh Walker Vehicle Locksmith Ltd | Wholesale & retail | 2021 |
| Joshs Autos Mobile Mechanic Limited | Wholesale & retail | 2025 |
| Joshua Wilson Limited | Manufacturing | 2024 |
| Josiah J Live Limited | Arts & recreation | 2023 |
| Josko Marek Limited | Other services | 2017 |
| Jospa Ocean Solutions Limited | Professional & scientific | 2020 |
| Joy&Co Ltd | Manufacturing | 2019 |
| Joymalgh Limited | Households | 1977 |
| Joyspedition Ltd | Transport & logistics | 2023 |
| Jozef GRP Yacht Ltd | Professional & scientific | 2020 |
| JP Aviation Ltd | Manufacturing | 2015 |
| JP Publishes Limited | Information & communication | 2022 |
| JP Westcountry (Holdings) Limited | Financial services | 2025 |
| Jpad Limited | Information & communication | 2010 |
| JPE Healthcare Ltd | Administrative & support | 2025 |
| JPP Chromatography Limited | Manufacturing | 2005 |
| JR Building & Carpentry SW Ltd | Manufacturing | 2025 |
| JR Estates South West Ltd | Households | 2022 |
| JR47 Limited | Extraterritorial | 2014 |
| JRB Garage Services Limited | Wholesale & retail | 2016 |
| Jrgas Ltd | Construction | 2023 |
| JRH Enterprises Ltd | Professional & scientific | 2020 |
| JRJ Consulting SEO & Web Design Plymouth Limited | Information & communication | 2020 |
| JRL Logistics & Services Ltd | Wholesale & retail | 2025 |
| JRS Newquay Limited | Hospitality | 2025 |
| JS Accounting & Bookkeeping Limited | Professional & scientific | 2020 |
| JS Marketing SW Ltd | Administrative & support | 2022 |
| JS Squared Limited | Professional & scientific | 2021 |
| JS Wills Property Services Ltd | Construction | 2025 |
| JSD Architectural Design Ltd | Professional & scientific | 2014 |
| Jsfm Consulting Limited | Professional & scientific | 2005 |
| Jsfm Tamerton Limited | Professional & scientific | 1982 |
| JSJ Property Maintenance Ltd | Real estate | 2019 |
| Jsjj Ltd | Wholesale & retail | 2018 |
| Jsowden Global Business Services Ltd | Professional & scientific | 2017 |
| Jsowden Ltd | Professional & scientific | 2021 |
| JSP Assets Limited | Real estate | 2022 |
| JST Events Ltd | Arts & recreation | 2011 |
| Jstm Limited | Wholesale & retail | 2026 |
| JT 22460 Ltd | Construction | 2022 |
| JTC Motors Ltd | Wholesale & retail | 2021 |
| JTC Water Services Ltd | Water & waste | 2023 |
| JTK Group Limited | Information & communication | 2023 |
| JTP Transport Ltd | Transport & logistics | 2025 |
| JTS Consulting Services Ltd | Professional & scientific | 2020 |
| Jubb Consulting Engineers Limited | Construction | 2000 |
| Jubb Group Limited | Professional & scientific | 2016 |
| Jubiilant Enterprises Limited | Information & communication | 2024 |
| Jubits and West Retail Ltd | Wholesale & retail | 2019 |
| Judicare Legal Services Limited | Administrative & support | 2008 |
| Juice Media Design Ltd | Professional & scientific | 2009 |
| Jules Awakening Wellness Centre Ltd | Health & social care | 2013 |
| Julian Blazeby Solutions Ltd | Professional & scientific | 2021 |
| Julian Marks Estate Agents Limited | Real estate | 2011 |
| Julian Marks Financial Services Ltd | Financial services | 2024 |
| Julian Marks Holdings Limited | Financial services | 2025 |
| Julian Marks Property Management Ltd | Real estate | 2018 |
| Julios Group Limited | Transport & logistics | 2015 |
| Julya Nails Ltd | Other services | 2025 |
| Jumping JAX Limited | Arts & recreation | 2016 |
| Juntos 2011 Ltd | Real estate | 2011 |
| Jupiter Living Ltd | Wholesale & retail | 2013 |
| JUSJ76 Limited | Construction | 2018 |
| Just Carpentry Solutions Limited | Construction | 2010 |
| Just Code Ltd | Information & communication | 2011 |
| Just Ecommerce Ltd | Wholesale & retail | 2018 |
| Just Enough Brave Limited | Information & communication | 2015 |
| Just Fire Doors SW Ltd | Construction | 2024 |
| Just Flats Sales & Lettings Limited | Real estate | 2015 |
| Just Good Roofing Limited | Construction | 2024 |
| Just Junk Limited | Professional & scientific | 2017 |
| Just Like MUM Limited | Administrative & support | 2010 |